Black-and-White Tone Targeting

Transcription

1 Black-and-White Tone Targeting C H A P T E R OBJECTIVES After completing this chapter you will be able to: define and explain purposes of tone targeting and tone correction. describe and utilize systems used to measure tones and tonal range in photographs. convert a measurement taken in one tone-measuring system to anor system s measurement units. use Photoshop s tools to measure tones and tonal range in a photograph. explain variables in printing processes that impact tone targeting. use Photoshop s tools to perform tone targeting. use Photoshop s tools to compensate for dot gain. automate tone targeting process using Actions palette. improve poor originals through use of tone targeting. perform tone targeting and correction on an image to be reproduced by a specified printing process. 73

2 74 C HAPTER TWO tone correction tone targeting Although Photoshop has tremendous power to improve color photographs, vast majority of printed photographs are still reproduced in black-and-white. Photoshop has several features that will allow you to vastly improve appearance of printed black-and-white photographs. For example, using Photoshop you can make photographs appear lighter or darker and compensate for changes that are caused by inherent attributes of varying printing processes. Tone refers to darkness or lightness of areas within a black-and-white photograph. The process of making photographs appear more pleasing by lightening or darkening particular tones is called tone correction; process of compensating for changes that are caused by inherent attributes of varying printing processes is called tone targeting. Tone correction is covered in depth in Chapters 5 through 9. This chapter deals only with black-and-white tone targeting. The skills that you will learn in this chapter by targeting blackand-white photographs lay foundation for color targeting and correction activities you will perform later in this book. An Introduction to Black-and-White Tone Targeting Reproducing images involves a series of simulations (Figure 2.1). Consider a photograph of Grand Canyon printed in a magazine. A photographer uses a camera and film to capture a representation of canyon image on film is a simulation of real scene. Next, a photo processing lab develops film and uses it to print image onto a sheet of photographic paper, called a photographic print. The print is a simulation of a simulation of Grand Canyon. A scanner operator n places photographic print onto a scanner to create a digital file that represents photograph. The digital file is a simulation of a simulation of a simulation of Grand Canyon. The Photoshop operator n makes changes to digital file resulting in, you guessed it, a simulation of a simulation of a simulation of a simulation of Grand Canyon. Finally, completed file is output to make a simulation of a simulation of a simulation of a simulation of a simulation of Grand Canyon. When image is subsequently printed using a printing press, several more simulations may occur. By this point, it is a wonder that picture even resembles original scene!

3 Black-and-White Tone Targeting 75 Figure 2.1 Simulating an original scene Item Level of Simulation Grand Canyon Real Thing Camera Film First Level Photo Print Second Level Scanner File Third Level Edited File Fourth Level Computer Output Fifth Level Printed Sheet Sixth Level Effects of Simulation Each of steps outlined above can cause image s quality to deteriorate. For example, film itself cannot capture all subtle variations in tone in nature and also has built-in deficiencies that cause ugly patterns called grain. In addition, making a photographic print from film provides an opportunity for dust and dirt to become part of image. On positive side, making of photographic prints also allows skilled and talented photographic technicians to improve parts of image. Scanners, especially low-end desktop scanners, cause image degradation, especially in shadow areas. Laser printers and imagesetters may be incorrectly calibrated and yield halftone dot sizes that do not match values that exist in digital file. Finally, each printing process, in combination with substrate, causes halftone dot sizes to fluctuate. Fortunately, Photoshop allows you to take all se variables into account and adjust a photograph so that, when printed, it more closely resembles original scene. Unless an image is to be viewed only on-screen, primary goal of tonal manipulation is to account for various attributes of a particular reproduction process/ink/substrate combination using tone targeting. A secondary goal is to improve overall appearance of photograph using tone correction. Optical Density optical density (density) densitometer densitometric value An original scene may have an almost infinite tonal variation, from very white whites to very black blacks. Original black-and-white photographs are continuous tone images that have an infinite number of tones, but film and photographic paper on which an image is reproduced can reproduce far fewer tones than exist in original scene. The relative darkness of a particular tone is called optical density or simply density. The density of a given area is measured with a special measuring device called a densitometer and is expressed using densitometric values. Densitometric values are logarithms and, in printing and publishing applications, range from about 0.00 to 2.00 (for ink on

4 76 C HAPTER TWO highlight density shadow density tonal range flat photograph contrasty photograph paper). A detailed explanation of mamatics used to calculate densitometric values is beyond scope of this book. However, you should know that values close to zero are very white areas and values close to 2.00 are very black. In fact, an area that has a densitometric value of 0.00 reflects all light that strikes it and is not black at all. An area that has a densitometric value of 2.00 reflects only one percent of light that strikes it and is very black. There are two particular densitometric readings that are very important to tone targeting highlight density and shadow density. The highlight density is densitometric value of lightest spot in a photograph it has lowest densitometric value to be found anywhere in photograph. The shadow density is darkest spot it has highest densitometric value to be found in photograph. If you subtract highlight density from shadow density, result is tonal range. The tonal range is range of tones from high to low that an image possesses. A normal photograph usually has a tonal range from about 1.60 to If tonal range is less than 1.60, photograph does not contain much contrast and can be considered flat. If tonal range is above 1.80, photograph is contrasty and contains tones that are too dark. Very dark tones may be impossible to reproduce on a printing press. Even though tonal range may be normal, a photograph may still appear eir too light or too dark depending on where tones in photograph are clustered. If too many tones are dark, entire photograph will appear dark. Calculating Gamma Ratio White paper and black ink are customarily used to print a reproduction of a black-and-white photograph. A typical white paper may have a densitometric value of about 0.10, and a solid layer of black ink may measure about Therefore, printing process using this paper and ink combination would be able to reproduce a tonal range of 1.50 (1.60 to 0.10) or less. If original photograph has a tonal range of 1.95 and press can only reproduce a tonal range of 1.50, range of tones in printed reproduction will be compressed by at least This means that about one-fourth of tonal range of original photograph cannot be adequately reproduced using this ink and substrate combination.

5 Black-and-White Tone Targeting 77 gamma ratio Changing ink and substrate for a given photograph will change reproduction s tonal range. Using less-dense black ink or a less-white substrate will decrease reproduction s tonal range while using blacker ink and a whiter substrate will increase tonal range. Use of a colored substrate or colored ink will also decrease tonal range of a halftone reproduction. The ratio of tonal range of an original photograph to tonal range of reproduction is called gamma ratio. The formula for calculating gamma ratio is: tonal range of original gamma ratio = tonal range of reproduction If tonal range of original is 1.60 and tonal range of reproduction is 1.60, gamma ratio would be In such a case, every tone in original would be reproduced with a matching tone in reproduction. However, if original has a tonal range of 2.00 and reproduction has a tonal range of 1.50, gamma ratio would be gamma ratio = = tonal range of original tonal range of reproduction = 1.33 The higher gamma ratio number, flatter reproduction. The lower gamma ratio number, more contrasty reproduction. Gamma ratio can be plotted on a graph called a gamma curve, with tonal range of original shown on x-axis and tonal range of reproduction shown on y-axis. Figure 2.2a illustrates a 1.0 gamma curve. Notice it is a 45-degree line. In a gamma curve of 1.0, every tone of original would be reproduced with same tone on printed substrate. A 1.0 gamma curve can only occur if printed reproduction has same tonal range as original. For example, if both photograph and printed reproduction have a tonal range of 1.50, a 1.0 gamma curve could be used.

6 78 C HAPTER TWO Figure 2.2 Comparison of 1.00 and 1.33 gamma curves Tonal range of reproduction Tonal range of reproduction Tonal range of original Tonal range of original Figure 2.2a: 1.00 gamma curve Figure 2.2b: 1.33 gamma curve gamma NOTE The term gamma is used in several ways in this book. You have already seen term used as ratio of tonal range of an original photograph to tonal range of reproduction. Gamma is also name of a Macintosh Control Panel that is used to adjust balance of your monitor. Finally, gamma is used as name for a control, called Gamma slider, in Levels dialog box that you will use later in this chapter. In all cases, gamma refers to a change in contrast in a reproduction compared to original. Exercise 2.1 Figure 2.2b illustrates 1.33 gamma ratio calculated for previous example. Notice that curve in Figure 2.2b is flatter (not as steep) compared to curve in Figure 2.2a. Flatter curves cause flatter reproductions. The 1.33 gamma curve will reproduce almost every tone lighter than it appears on original. As you can see in Figure 2.2b, an area on original that has a densitometric value of 1.00 will be reproduced using a value of approximately 0.70, while a 1.33 area on original will be reproduced at The gamma curve can be adjusted to match tonal range of original and tonal range of reproduction process by using settings included in most desktop scanner programs. Many desktop scanner operating programs commonly use a default gamma of 1.8. This gamma is too high for many photographs and tends to flatten m too much. If you have a densitometer to read tonal range of an original photograph and if you know tonal range that reproduction process is capable of achieving, you can preset gamma before scanning. The tonal range of reproduction is completely dependent on printing process, substrate, and ink to be used. To obtain satisfactory results, you must always find out in advance, from your print provider, tonal range that will be possible given unique combination of se three variables. Calculating Gamma Ratio for a Given Original and Process/Substrate/Ink Combination In this exercise, you will calculate gamma ratio value to be entered when scanning a black-and-white photograph. Assume that original has a highlight density value of 0.15 and a shadow density of Also assume that your print provider informed you that printing process,

7 Black-and-White Tone Targeting 79 substrate, and ink that will be used to print final reproduction can produce a tonal range of Calculate tonal range of original: tonal range = shadow density highlight density = = Calculate gamma ratio: ( tonal range of reproduction is given above) gamma ratio = = tonal range of original tonal range of reproduction = You would enter a gamma ratio value of 1.14 (or as close as you can) into scanner software if you were scanning this particular photograph. The gamma curve would measure 1.14 and would be flatter than a 45-degree line. The Goal of Halftone Reproduction To minimize effects of tonal compression, a printed halftone should contain lightest and darkest tones a process is capable of producing. This could be done by printing no dots at all in highlight areas and printing a solid layer of ink in shadows. However, unprinted and solid black areas in middle of a halftone are painfully obvious. Figure 2.3 is a high-resolution unaltered version of photograph you will open in Exercise 2.3. Notice solid white area between girl s shoulder and her hair and solid black areas toward bottom of her chin and on right side of her face. These areas appear unsightly. To prevent se unattractive too-white or too-black areas in a printed halftone reproduction, goal, when preparing most photographs for reproduction, is to position smallest consistently printable dot in highlight density and largest consistently printable dot in shadow density. In or words, every part of a halftone should consist of dots and every printable dot size should be used in most halftones.

8 80 C HAPTER TWO Figure 2.3 A high resolution version of Project2.eps image that contains unprinted and solid black area 1 1. Too-light area (unprinted) 2. Too-dark area (solid black) 2 specular highlight phantom halftone Exceptions to Rule As in case of every rule, re are exceptions to this goal. There are cases when a small area in a photograph is much whiter than rest of image for example, a reflection of a flash in a mirror. These small abnormally white areas are called specular highlights and can be printed blank that is, without any dots. Anor exception would be when printing a very light photograph called a phantom halftone. Because phantom halftones must be very light (sometimes type is superimposed over m), no large dots are used at all. Using Densitometric Values Densitometric values are one of primary quality control systems used by printing and publishing industries. Densitometric values are used to measure original photographs, film that is imaged on imagesetters or cameras, and layers of printed ink. In fact, densitometric values are used in just about all phases of printing and publishing except in Photoshop unfortunately, software engineers that developed Photoshop decided against incorporating standard densitometric values into its interface. Even though Photoshop does not use densitometric values, you need to become familiar with m because of ir widespread use in controlling quality in printing and publishing industries. You can use Eyedropper tool and a Percent Dot Value to Density Value table to convert halftone dot values to corresponding densitometric values (Table 2.1).

9 Black-and-White Tone Targeting 81 Table 2.1 Percent Dot Value to Density Value Percent dot value Density value Percent dot value Density value Relating Densitometric Values to Photoshop s Tone Values Instead of using densitometric values, Photoshop uses numbers ranging from 0 to 255 to describe value of tones. These values relate to 256 shades of gray that PostScript is capable of producing. A zero value is black, while a value of 255 is pure white. If you ever need to

10 82 C HAPTER TWO convert a Photoshop tone value to a halftone dot value, use following formula: ( ) halftone dot value = 1 X 255 when x = Photoshop tone value. The halftone dot value can n be converted to a densitometric value using Table 2.1. Exercise 2.2 Converting a Photoshop Tone Value to a Densitometric Value In this exercise, you will calculate densitometric equivalent of a Photoshop tone value. Assume a given pixel has a Photoshop tone value of 64. Calculate its halftone dot value and densitometric value. 1. Use formula below, substitute 64 for x. ( ) halftone dot value = 1 X Solve equation as follows: ( ) halftone dot value = 1 X 255 ( ) = = = 1 (.25) 75% 3. Use Table 2.1 to convert a 75% halftone dot value to a densitometric value. Because re is no 75% halftone dot value shown in table, use value that falls between densitometric values of 74% halftone dot value and 76% halftone dot value. The result is a densitometric value of 0.60.

11 Black-and-White Tone Targeting 83 NOTE Exercise 2.3 If you are using your own computer and have not made any changes since you completed Chapter 1 of this text, you do not need to do Step 1. NOTE Make all changes to application window described in Exercise 1.2. NOTE If you were to close Navigator/Info/Options and Layer/Channels/ Paths palettes before clicking Zoom pointer over photograph, window would increase in size so that entire image would be displayed on screen. Preparing Photoshop Windows and Opening a Photograph In this exercise, you will use steps you learned in Chapter 1 to prepare application and document windows n open a black-andwhite photograph. 1. Turn on your computer. If you are working in a student laboratory, erase Photoshop 4.0 Prefs from Preferences folder within System folder. If you are working in a student laboratory, delete Photos40.PSP file in Adobe/Photoshop/Prefs subdirectory using Windows Explorer or Windows File Manager. 2. Launch Photoshop 4.0, n make any necessary adjustments to application window so that it resembles Figure 1.8 on page From File menu, choose Open. 4. Navigate to Photoshop Student Files Folder, open C2exercise.tiff ( C2exer.tif) file, n click OK when locked file message appears. C2exercise.tiff opens in its own document window. 5. From View menu, choose Show Rulers, or use keyboard shortcut On Tool palette, select Zoom tool. 7. Click Options tab on Navigator/Info/Options palette. Then, select Resize Windows To Fit checkbox. The Resize Windows To Fit option causes document window to automatically enlarge or reduce in size when Zoom tool is used to change magnification of image. 8. Move Zoom pointer over photograph, n click anywhere within image. The image is magnified to 200% and document window enlarges to display more of image. Note that document window does not extend under Navigator/Info/Options and Layers/Channels/ Paths palettes (Figure 2.4). Therefore, your view of image is not obstructed by palettes.

12 84 C HAPTER TWO Figure 2.4 C2exercise enlarged to 200% 1. The window does not extend under open palettes. 1 Exercise 2.4 Measuring Densitometric Values In this exercise, you will use Eyedropper tool to measure Photoshop s halftone dot values and convert Photoshop s halftone dot values to densitometric values. 1. If necessary, scroll so that child s face is visible in document window. 2. Click Info tab on Navigator/Info/Options palette. 3. From Tool palette, select Eyedropper tool. Then move pointer around in child s face and notice halftone dot values displayed in Halftone Dot Percentage field in Info palette. 4. Stop moving Eyedropper pointer when its tip is over highlight on child s nose at approximately coordinates X: 2.771, Y: (Figure 2.5).

13 Black-and-White Tone Targeting 85 Figure 2.5 Area to measure with Eyedropper pointer 1. Measure area shown at tip of Eyedropper tool. (XY coordinates shown on Info palette.) 1 NOTE The location of X and Y coordinates of Eyedropper pointer shown in lower left corner of Info palette were captured on a 17-inch monitor with an monitor setting. 5. Depending on where point of Eyedropper pointer is when you look at Info palette, Halftone Dot Percentage value may read from 51% to 58%. If you stop in exactly same place as shown in Figure 2.5, Halftone Dot Percentage field will read 53%. 6. Use Table 2.1 to convert a 53% halftone dot value to a densitometric value. You can see from chart that this area has a densitometric value of Density Areas of Importance to Black-and-White Tone Targeting highlights midtones shadows When performing basic tone targeting in a black-and-white photograph, re are three areas that are important to consider. These are highlight, midtone, and shadow areas of a photograph. Highlights are whitest areas of photographs, usually have densitometric readings between 0.00 and 0.15, and are reproduced with halftone dots ranging from 0 to 29%. Midtones are gray areas of a photograph. They have densities ranging from approximately 0.16 to 0.50 and are usually reproduced with halftone dots ranging from 30 to 70%. Shadows are darkest areas of a photograph. These areas have densities above 0.50 and are usually reproduced with dots that are larger than 70%.

14 86 C HAPTER TWO Exercise 2.5 Finding Highlight and Shadow Densities of a Photograph and Calculating Tonal Range In this exercise, you will use Eyedropper tool to find highlight and shadow densities of a photograph and calculate its tonal range. You will also save image as an EPS file. 1. Make sure Eyedropper tool is still selected, magnification of image is still 200%, and image appears as shown in Figure Move Eyedropper pointer around image to measure lightest and darkest areas of photograph. Find locations of lowest halftone dot value and highest halftone dot value. Write down X and Y coordinates for each location. You should find 0% and 98% halftone dot values in areas indicated by pointers on Figure 2.6. These are highlight and shadow densities, respectively. Figure 2.6 Locations of highlight and shadow densities 1 1. The shadow density area 2. The highlight density area 2 3. Convert halftone dot values to densitometric values. From Table 2.1 on page 81, you will notice that a 0% halftone dot value corresponds to a 0.00 densitometric value and that a 98% halftone dot value corresponds to a 1.70 densitometric value.

15 Black-and-White Tone Targeting Calculate tonal range. Tonal range = Shadow density Highlight density 1.70 = NOTE You do not need to do Step 6 if you are saving on hard drive or server. Because value falls between 1.60 and 1.80, tonal range is considered normal. 5. Return magnification to 100%. 6. Insert your Photoshop Files 1 disk into disk drive. 7. From File menu, choose Save As. 8. Navigate until name of your Photoshop Files 1 disk or folder appears at top of dialog box. 9. Save your file as Project2.eps on your disk using Photoshop EPS format. 10. When EPS Format dialog box appears, do not select Include Halftone Screen or Include Halftone Function options. Do not change any of defaults. Click OK to save file to your disk. Using a Histogram Photoshop can show you a graphic representation of tonal range of photograph displayed on screen. You can see this representation by choosing Histogram from Image menu (see Figure 2.7). Unfortunately, it displays information about photograph using Photoshop s tone value system rar than easy-to-understand halftone dot values. The components of Histogram window are explained in Table 2.2.

16 88 C HAPTER TWO Table 2.2 Elements of Histogram window Element Blended horizontal bar Histogram graph Mean Std Median field Dev field field Function Contains a blend from dark to light. It indicates that dark pixels are plotted on left side of graph, gray pixels in center, and light pixels on right. A graphic display of number of pixels at each value portrayed by blended horizontal bar. The shape of graph is very important. If graph shows most of pixels clustered at left side, photograph is very dark. Similarly, too many pixels at right side indicate a too-light image. Ideally, most pixels should be clustered at center of graph. In most cases, pixels should be displayed all along graph from left to right. The average Photoshop tone value of pixels in image. This average can be converted to a halftone dot value using Table 2.1 and formula in Exercise 2.2. The standard deviation of distribution of Photoshop tone values that exist in image. The smaller this number, more similar tones. A large Std Dev number indicates a photograph that contains a wide range of tones. The Photoshop tone value lightest and darkest tone. of tone that is exactly halfway between P ixels field The total number of pixels in image or selection. Level Count field field Percentile field When pointer is positioned anywhere in histogram graph, displays Photoshop tone value of that location. this field The number of pixels that have Photoshop tone value at location where t he pointer is positioned. ( Note: This field only displays a number when pointer is positioned over histogram graph.) Indicates percentage of all pixels that are darker than Photoshop t one value at location where pointer is positioned. ( Note: This field only displays a number when pointer is positioned over histogram graph.) Exercise 2.6 Viewing and Interpreting a Histogram In this exercise, you will use display and interpret a Histogram of tonal values contained in Project2.eps image. 1. From Image menu, choose Histogram. The Histogram window is displayed (Figure 2.7).

17 Black-and-White Tone Targeting 89 Figure 2.7 The Histogram window for Project2.eps file 4 1. Blended horizontal bar. 2. Histogram graph 3. These fields are only active when pointer is placed over histogram graph. 4. A black-and-white photo contains only one channel black Move pointer anywhere in bottom half of window. Notice following information displayed in window: The blended horizontal bar in center of window. Notice shape of histogram. It indicates that this is a very dark photograph because majority of pixels are on left side of graph. Notice that re are some highlights, but very few midtones. This photograph will not reproduce well because too many tones fall on left side of graph. The Mean field indicates average pixel has a Photoshop value of You can convert mean Photoshop tone value to halftone dot value and densitometric value using formula and Table 2.1 used previously. (The mean Photoshop tone value of corresponds to a halftone dot value of 62% and a densitometric value of 0.44.) The Std Dev field indicates that standard deviation of tones in this image is The Median field indicates median Photoshop tone value in this image is 64. Using Table 2.1 and formula found in Exercise 2.2, this Photoshop tone value can be converted to a halftone dot value of 75% and a densitometric value of These values indicate that this is a very dark photograph because halftone values above 70% are shadows. The Pixels field indicates re are 59,040 pixels in image.

18 90 C HAPTER TWO 3. Move pointer into graph area. Notice that fields on right side of window become active. 4. Move pointer around within graph. As you move pointer, look at Photoshop tone value in Level field. Notice that farr you get to left edge of graph, lower Photoshop tone value displayed in Level field. Notice also that Photoshop tone values are higher toward right side of graph. Remember that a Photoshop tone value of zero is black and a Photoshop tone value of 255 is white. 5. Move pointer until Level field reads 84 (84 is equivalent to a 67% halftone dot value and a 0.48 densitometric value). Notice Count and Percentile fields. The Count field indicates how many pixels have a Photoshop value of 84 (re are 220). The Percentile field indicates percentage of all pixels in image that are 84 or darker. It means that 68.28% of all pixels have a 67% or larger halftone dot value. Once again, this indicates it is a very dark photograph. 6. Move pointer until Level field reads 5. Notice that re are no pixels with a level of 5 or less. 7. When you are finished looking at Histogram, click OK. Tone Targeting for Specific Printing Processes Photoshop can be used to alter black-and-white images in two ways. First, it can be used to correct defective photographs those that are too light, too dark, or lacking in contrast. You will learn to improve appearance of defective photographs in Chapters 5 through 7. Photoshop can also be used to target particular halftone dot sizes to highlight, midtone, and shadow areas of photograph. The choice of a particular size of halftone dot to position in each area depends on combination of printing process and substrate that will be used to print photograph. Each printing process puts ink on substrates using different methods. The way ink is printed impacts size of individual halftone dots that can be reproduced. In Chapter 1, you learned in Table 1.5 on page 54 that printing process affects lpi of

19 Black-and-White Tone Targeting 91 screen that can be printed. In addition, printing process influences smallest and largest halftone dots that can be printed. For example, gravure printing process is capable of printing smaller dots than screen process printing. The soft plates used in flexography cause halftone dots to become enlarged, so smaller dots are specified for highlights printing process will n enlarge m to appropriate size. Each printing process has particular attributes that cause certain effects. The attributes of a process are not faults y are simply inherent in particular process. It is ultimately responsibility of Photoshop technician to take attributes of printing process into account when performing tone targeting. Or factors that affect smallest and largest printable dots include lpi (very large or very small dots using high lpi screens are usually more difficult to print), ink (thinner inks tend to blot more into paper causing it difficult to maintain very large dots), and absorbency and smoothness of substrate (very small and very large dots on rough and on very absorbent surfaces are harder to print). fingerprinting Fingerprinting Ideally, each combination of printing press, ink, and substrate should be fingerprinted. Fingerprinting refers to printing a series of tests to determine smallest and largest dots a particular press can produce using a specified lpi on a particular substrate using a particular ink. To fingerprint a press, prepare an image consisting of a series of different sizes of halftone dots, similar to illustration in Figure 1.13 on page 20. The dots should include a range of sizes from about 2% to about 98%. It is not necessary that each percent dot size be printed. However, a range of very small dots and very large dots should be represented. This series of halftone dots should be printed on each common combination of press, ink, and substrate typically used in a particular plant. The smallest and largest consistently attainable halftone dot sizes should n be recorded. Well run professional printing businesses will have this information available for use by Photoshop and or desktop/ prepress operators.

20 92 C HAPTER TWO Because you probably do not have access to fingerprinting data for a variety of printing processes, Table 2.3 presents some rules of thumb that reference books and/or professional printing businesses recommend for largest and smallest halftone dots that can be reproduced using various processes and substrates. It is important that you understand that use of Table 2.3 for particular jobs is comparable to healing yourself by using a medical encyclopedia unless someone who knows what he or she is doing runs some tests, you are just guessing! Table 2.3 Examples of highlight and shadow dot sizes for various processes and substrates Process/Substrate/lpi Smallest Highlight Dot Largest Shadow Dot Offset lithography/uncoated Offset lithography/coated 2 95 Flexography/all substrates 3 85 Gravure/coated 3 98 Gravure/uncoated 5 90 Screen/50 to 65 lpi 3 95 Screen/85 lpi 5 92 Screen/150 lpi Targeting Tones Using Levels Dialog Box Once you understand that primary goal of tone targeting is to account for various attributes of a particular process/ink/substrate combination, targeting tones in a black-and-white image is a fairly straightforward task. In next few exercises, you will use knowledge you have gained so far to target tones in black-and-white photographs. To target tones, you will use Levels dialog box (see Figure 2.8). The Levels dialog box contains several elements that are summarized in Table 2.4.

21 Black-and-White Tone Targeting 93 Table 2.4 Elements of Levels dialog box lement E n Functio istogram H s Level in shown Histogram window is in viewed histogram as same The box. dialog sliders nput I d use are sliders These histogram. under sliders appear triangles called Three image. of contrast increase to slider input lack B. shadows increase to Used slider input hite W. highlights increase to Used slider input amma G a gamm The photograph. of contrast, midtone or gamma, adjust to Used adjusted. is shadow slider or highlight eir when automatically moves slider manually. moved be also can slider gamma The fields Levels Input shadow densities. and highlight of location current for values Photoshop values. gamma standard using ratio gamma current indicates field center The Levels Output sliders image. in contrast decrease to Used slider output lack B. shadows Decreases slider output hite W. highlights Decreases fields Levels Output shadow densities. and highlight of location current for values Photoshop review option P g makin are you changes display to Photoshop causes option this checked, If screen. on image to Save and Load buttons with used previously settings load or settings box dialog Levels save to Used images. or button ancel C y an making without box dialog Levels closes button Cancel Pressing Pressing hanges. c ] tion p g Clickin Reset. to change to button Cancel causes Levels when were y way to return to adjustments all causes Reset opened. was box dialog button uto A t i assign and pixel whitest find to Photoshop causes button Auto Pressing a it assigns and pixel darkest finds also It 255. of value tonal Photoshop a Pressing 0. of alue v ] tion p. Options to change to button Auto causes Optio [ o Aut + button amount set to box dialog this Use box. dialog Options Range Auto Opens highlights specular of amount is, feature that Auto by used clipping of is default The clicked. is button Auto when allowed be will that shadows and or highlights specular of amount increases percent larger a Entering.5%. recommended. not are defaults to Changes image. an in shadows yedroppers E a of shadow areas and midtone, highlight, choose manually to Used correction. tone performing when seldom necessary is use Their photograph.

22 94 C HAPTER TWO Using Levels Sliders You use Input sliders in Levels dialog box to increase overall contrast of an image and you use Output sliders to decrease overall contrast of an image. You must understand what Photoshop is doing internally so that you can take full advantage of tool. Moving Input sliders (black or white) in toward center has effect of increasing overall contrast of image. Why does this increase contrast, you might ask? When you drag black input slider away from zero (its default position) to a higher level, Photoshop maps all pixels at that new level and lower (those to left) to 0 (black), and it stretches all pixels with higher values to fill entire tonal range from 0 to 255, thus creating more difference between adjacent pixels (increasing contrast). If you set black input slider to 20, n all pixels at levels 0 through 20 are mapped to level 0 and pixels above 20 are mapped to proportionately darker values (pixels previously at 25 might become 4, for example). This darkens image and increases contrast in shadows. Moving Input white slider has same effect at opposite end of tonal range. As you move it away from 255 (its default position) to a lower level, Photoshop maps all pixels at that level and higher (those to right of slider) to level 255 (white), and stretches all levels to left of slider to fill entire tonal range from 0 to 255, thus creating more difference between adjacent pixels (increasing contrast). If you set white input slider to 233, n all pixels at levels 233 through 255 are mapped to level 255 and pixels at levels lower than 233 are mapped to proportionately lighter values (pixels previously at 228 might become 248, for example). This lightens image and increases contrast in highlights. The gamma slider lets you adjust midtones without affecting highlights or shadows, resulting in an image that is darker or lighter overall. When you move gamma slider, Photoshop moves level associated with midtone gray value ( fiftieth percentile). If you move gamma slider to left (toward 0), image gets lighter, because you are mapping a darker value to be new midpoint (fiftieth percentile). In effect, you are stretching remaining pixels in shadows to fill up lower half of tonal range, and you are squeezing extra pixels into upper half of tonal range, where

23 Black-and-White Tone Targeting 95 highlights are located. Conversely, if you move gamma slider to right (toward 255), image gets darker because you are mapping a lighter value to be new midpoint (fiftieth percentile). The result is that you stretch remaining pixels in highlights to fill up upper half of tonal range, and you squeeze extra pixels into lower half of tonal range shadows. The Output Levels controls let you flatten tonal range of image so that you can target an image to attributes of a specific printing process/substrate combination. Decreasing tonal range decreases overall contrast in an image. How can that be? As you increase value of black output slider, pixels with levels of 0 are remapped to new level and pixels with higher levels are mapped to proportionately lighter values. If you move black output slider to 20, n pixels with values of 0 are mapped to 20 and higher values are mapped to proportionately lighter values. This limits darkest pixels in image to level at which slider is set. If you set black Output Levels slider to 20, distinction between levels is maintained, but pixels that were at level 0 go to level 20, those at level 1 go to level 21 and so on. As tonal range gets decreased, contrast is decreased. The white Output slider behaves same way as black Output Levels slider. If you set slider to level 240, all pixels at level 255 are mapped to 240, and so on. Table 2.5 summarizes use of Levels input and output sliders to darken or lighten an image. Table 2.5 Levels Adjustments with Input and Output Sliders T o darken a channel: To lighten a channel: Highlights Midtones Shadows Move left Highlight Output slider to Move Gamma slider to right Move Shadow Input Slider to right Move Highlight Input Slider to left Move Gamma slider to left Move Shadow Output slider to right You will regularly use Output Levels fields to compress tonal range to match a given printing process/substrate combination. Compressing tonal range can be done quite simply by first clicking

24 96 C HAPTER TWO Auto button, which sets highlight density to a zero percent halftone dot value and shadow density to a 100% halftone dot value. Then, use Output Levels field or sliders to match appropriate highlight and shadow dot values for correct printing process/substrate combination. If you use Output Levels fields, you can quickly set highlight and shadow halftone dot values with Photoshop tone values given in Table 2.6. Table 2.6 Dot percent sizes and corresponding Output Levels values To set highlight dot percent to: Set highlight Output Level (Photoshop tone values) to: To set shadow dot percent to: Set shadow Output Level (Photoshop tone values) to: Exercise 2.7 Using Levels Dialog Box to Adjust Highlight and Shadow Dot Sizes In this exercise, you will use Levels dialog box to correct highlight and shadow dot sizes for Project2.eps image. Assume that your instructions are to prepare this image for reproduction by offset lithography on uncoated paper. 1. Make sure Eyedropper tool is chosen. 2. From Image menu, select Adjust, n choose Levels from submenu. Alternatively, you can press +. The Levels dialog box appears. 3. If necessary, drag title bar of Levels dialog box so that you can see highlight and shadow densities previously located and displayed in Figure 2.6.

25 Black-and-White Tone Targeting 97 Figure 2.8 The Levels dialog box When you are finished, screen should look like Figure 2.8. Notice histogram, input and output sliders and fields, buttons, and options. Table 2.4 provides an explanation of most of se items. 1. Histogram 2. Input sliders 3. Output sliders 4. Decreases shadows 5. Increases shadows 6. Adjusts gamma 7. Increases highlights 8. Decreases highlights 9. Auto density button 10. Output levels fields 11. Input levels fields NOTE If Step 5 does not work as indicated, your Preferences file is not set to defaults. Quit Photoshop and follow Exercise 1.1 on page Click Preview option to select it. 5. Click Auto button. This causes Photoshop to place a 0% dot in highlight density and a 100% dot in shadow density. Notice that shadow input slider moved to coincide with left edge of histogram and that shadow Input Level field changed to a value of Determine correct values for highlight and shadow dot values. First, consider printing process and substrate combination offset lithography on uncoated paper. Then, use Table 2.3 on page 92 to look up proper highlight and shadow halftone dot sizes 10% and 90% respectively (please remember that Table 2.3 is only a guide if you have real fingerprinting information available, use it).

26 98 C HAPTER TWO 7. Move Eyedropper pointer into area beneath child s hair and above her shoulder highlight density previously identified in Figure 2.6. The Halftone Dot Percentage value in Info palette should read 0. Notice change in Info palette halftone dot fields have expanded to provide two columns of numbers. The left number refers to old halftone dot value of area at tip of Eyedropper pointer as it was when you opened Levels dialog box. The right value indicates new halftone dot value resulting from changes made since Levels dialog box was opened (Figure 2.9). Figure 2.9 The expanded Info palette 2 1. Old halftone dot values 2. New halftone dot values 1 8. Use mouse to move White Output Slider to left to darken (decrease) highlights until Highlights Output Level field reads about Move Eyedropper pointer into highlight density area identified in Figure 2.6. Look at Info palette. The Halftone Dot Percentage field should read 0%/10%. The field reading 0%/10% means that highlight density that used to measure 0% now measures 10%. The 10% reading matches highlight dot value required for offset lithography on uncoated paper. 10. Move Black Output Slider a little bit to right to lighten (decrease) shadows. After you have moved slider, move Eyedropper pointer into shadow density area. 11. Move Eyedropper pointer around in shadow areas of photograph and look at new halftone dot values on Info palette. You should see no new halftone dot value greater than 90%. If you do see a value above 90%, move Black Output Slider

27 Black-and-White Tone Targeting 99 Figure 2.10 The Levels dialog box after highlight and shadow halftone dot values have been corrected more to right. If all values are below 90%, move Black Output Slider to left. When you are done, Output Levels shadow field will read about 25 (Figure 2.10). 12. Click OK to accept changes you have made to image. Look at image. It probably looks light to you. This is good. Remember that printing process will darken images! 13. From File menu, choose Save to save your changes. dot gain Dot Gain Dot gain is a phenomenon that occurs in most printing processes. Dot gain causes halftone dots to print larger than y are supposed to. For example, suppose you specify a halftone dot size of 50%. The pressure used to transfer ink to substrate, coupled with blotting action of many papers, causes dots to become enlarged. So, 50% dots can end up looking like 70% dots. Dot gain is not an error or flaw it is an attribute of print reproduction. It does, however, make halftones look darker than y should. So, you must take dot gain into consideration when performing tone targeting. To see what happens when dot gain is not considered, compare midtones in Figure 2.3 on page 80 with those in Figure 2.14 on page 104. Figure 2.3 illustrates how your Project2.eps image would appear if dot gain were not considered. An accommodation for dot gain has been made in Figure Dot gain affects midtones more than highlights or shadows. The larger circumference of dot, more likely it will be affected by dot gain. However, very large dots start to overlap, so y do not gain too much. Tiny highlight dots are usually not greatly affected by dot gain eir. Because of considerable impact of dot gain on midtones, dot gain is usually measured at 50% dot. Using same

28 100 C HAPTER TWO sort of test that is used to fingerprint a press, a 50% dot s size is measured with a densitometer or or dot-measuring device. The dot will usually read between 65 to 85%, a gain of 15 to 35%. Fifteen percent is considered acceptable dot gain, 20% is normal, and 35% is generally considered unacceptable. You should be aware that laser printers and office copy machines reproduce images with a very high degree of dot gain. Many of se machines print images using powder crystals called toner rar than with ink. Dots printed with toner generally appear larger than dots printed with ink. In addition, higher lpi dots tend to gain more on laser printers than lower lpi screens. For example, one tested 300 dpi laser printer produced dot gain of about 19% when set to 35 lpi and 29% when set to 53 lpi (which is printer s default lpi). The exaggerated amount of dot gain inherent in toner-based printing systems is reason why image you will print on a laser printer in Exercise 2.14 will look very dark. The impact of dot gain is to darken midtones without affecting eir highlights or shadows very much. When performing tone targeting, you must set midtones to look much lighter than you would normally expect. Dot gain will darken midtones for you. You use Gamma Input Slider to adjust gamma, or midtone contrast, of photograph (see Figure 2.9). Exercise 2.8 Using Levels Dialog Box to Compensate for Dot Gain In this exercise, you will continue to target Project2.eps image by adjusting Gamma slider in Levels dialog box to compensate for dot gain. Assume that anticipated dot gain for printing process/ substrate combination is 20%. 1. From Image menu, select Adjust, n choose Levels from submenu. Alternatively, you can press +. Notice how histogram has changed to reflect changes you previously made to highlight and shadow density halftone dot values. In particular, notice that White and Black Input Sliders appear outside histogram. This indicates that original tonal range has been compressed to match process/substrate characteristics.

29 Black-and-White Tone Targeting 101 Figure 2.11 illustrates this tonal compression. The figure, which is not visible on your monitor, was prepared by overlaying contents of Levels dialog box as it appeared at beginning of Exercise 2.7 with contents of Levels dialog box now displayed on your monitor. The black histogram represents tonal range before it was compressed to match characteristics of printing process/ substrate combination. The gray histogram represents tonal range after highlight and shadow dots were targeted. Note that gray tonal range is shorter than black tonal range and that gray tonal range provides neir as white whites nor as black blacks as tonal range illustrated in black. Figure 2.11 Tonal compression caused by matching original tonal range (black) to characteristics of process/ substrate (gray) 1. Tonal range of photograph before highlight and shadow halftone dot sizes were targeted. 2. Tonal range after targeting of highlight and shadows was completed Move Eyedropper pointer around image until you find an old halftone dot percentage value of about 70%. The halftone dot value doesn t need to be exactly 70%. Any dot between approximately 60% to 80% is acceptable. You will find several values in this range around child s eye. Write down X and Y coordinates for location of chosen halftone dot value. 3. After you have located an area with appropriate-sized dots, consider effect of dot gain. Dot gain causes midtone dots to become enlarged. You have been instructed to plan on a dot gain of 20%, so a 50% dot will print as if it was a 70% dot. To compensate for this phenomenon, you must

30 102 C HAPTER TWO decrease size of a 70% dot until it measures 50%. When this 50% dot is printed, dot gain will cause it to expand to 70. Thus, tonal values of image will be restored. 4. Move Gamma Input Slider a bit to left to lighten midtones (see Figure 2.8 for location of Gamma Input Slider). 5. After you have made a gamma (midtone) adjustment, move Eyedropper pointer to location of your chosen midtone dot. The Halftone Dot Percentage value in Info palette should indicate a new halftone dot value that is 20% less than old halftone dot value. 6. If new halftone dot value is between old value and 20% less than old value, move Gamma Input Slider farr to left. If new halftone dot value is less than old value minus 20%, move Gamma Input Slider to right. You are finished when old and new halftone dot values are 20% apart. For example, if you had a 69% halftone dot value, new value should be 49% (Figure 2.12). Figure 2.12 Gamma adjusted in Levels dialog box Location of area measured 2. 20% difference between old and new values

31 Black-and-White Tone Targeting Click OK to accept your changes. The image on screen looks very flat and light. Do not worry. Remember that printing process darkens images. 8. From Image menu, choose Histogram. The Histogram window appears (Figure 2.13). Notice that many more pixels are now clustered around middle of histogram. Also notice vertical white streaks that appear in histogram. These streaks represent tonal values in which no pixels exist. To make corrections you specified in Levels dialog box, contrast between midtones and shadows was increased, leaving some Photoshop tone values unused. Finally, notice median Photoshop tone value about 125. This value is about halfway between 0 and 255 and represents a big improvement over original distribution of tones (see Figure 2.7). Figure 2.13 The Histogram after highlights, shadows, and midtones have been adjusted. 1. Pixels are more clustered around center compared to Figure The median field is Vertical white streaks indicate unused tone values Click OK to close Histogram window (Figure 2.14). Compare Figure 2.14 to Figure 2.3 to see improvement in photograph.

32 104 C HAPTER TWO Figure 2.14 A high resolution version of Project2.eps image after tone targeting has been applied. 10. From File menu, choose Save to save this image. Using Basic Black-and-White Tone Targeting to Improve Appearance of a Flat Photograph Often, performing necessary targeting procedures for a grayscale or black-and-white image improves overall appearance of a photograph, thus eliminating need to do any or corrections. In Exercises 2.9 and 2.10, you will start with a very defective photograph it is so light that you can barely see it n use Levels dialog box to target highlights, midtones, and shadows to compensate for dot gain and or press characteristics. This process will greatly improve overall appearance of photograph as well as target its tones for print reproduction. NOTE Exercise 2.9 Do not close Project2.eps. Targeting a Very Flat Photograph for Flexographic Reproduction In this exercise, you will open a very flat photograph, use Levels dialog box to improve tonal distribution of photograph, and target it for printing by flexography. Assume that your instructions are to prepare this image for reproduction by flexography and that common dot gain for this process is 25%. 1. Open file called C2exercise2.tiff ( C2exer2.tif), found in Photoshop Student Files folder. Click OK when locked file message appears. Notice that image is very flat and lacks contrast.

33 Black-and-White Tone Targeting 105 Figure 2.15 The adjusted Input Levels and Output Levels fields 2. From File menu, choose Save As. Navigate to your Photoshop Files 1 disk or folder. Name file Project2b.eps, n save it as a Photoshop EPS file. Accept all default options in EPS Format dialog box. 3. From Image menu, select Adjust, n choose Levels from submenu. The Levels dialog box appears. 4. Click Auto. Photoshop automatically gives highlight density a zero percent halftone dot value and shadow density a 100% halftone dot value, thus lengning its tonal range. Notice improvement in appearance of photograph. 5. Consider smallest and largest halftone dots that printing process/substrate combination can produce. Use Table 2.3 on page 92 to look up flexography (all substrates). The minimum and maximum dot sizes are 2% and 80%, respectively. 6. Use Table 2.6 on page 96 to determine Output Levels that will result in 2% highlight and 80% shadow dots. The corresponding levels are 250 and 51, respectively. 7. In Shadow Output Levels field, type 51 ; and in Highlight Output Levels field, type 250 (Figure 2.15). The image changes to reflect your changes.

34 106 C HAPTER TWO NOTE It is always best to accept changes to highlight and shadow halftone dot values and n reopen Levels dialog box to adjust midtones. Clicking OK to accept changes causes tonal range and histogram to be updated to include changes you made to highlight and shadow halftone dot values. It is easier and more accurate to adjust midtones after tonal range has been updated. Exercise Click OK to accept changes to highlight and shadow halftone dot values. 9. Open Levels dialog box again. Notice how histogram has been stretched in comparison to histogram of uncorrected image (compare it to histogram in Figure 2.15). 10. Use Gamma Input Slider to decrease halftone dot values of midtones (50 to 70%) by specified dot gain value (25%). Use same procedures you followed in steps 2 through 6 of Exercise 2.8. When you are finished, image on screen will look very light because of large amount of dot gain inherent in flexographic printing process. When it is printed, photograph will darken appropriately. 11. When you are finished, click OK. Targeting a Very Flat Photograph for Offset Lithographic Printing In this exercise, you will use Levels dialog box to improve tonal range of a photograph and prepare it for printing. Assume that your instructions are to prepare this image for reproduction by offset lithography on coated paper and that common dot gain for this process/substrate combination is 15%. 1. From File menu, choose Revert. Click Revert when an alert appears. The Revert command discards all changes that have been made since you last saved and displays last saved version on screen. 2. Open Levels dialog box. 3. Click Auto. 4. Use Tables 2.3 and 2.6 to determine smallest highlight and largest shadow that this process/substrate combination can accommodate and corresponding Output Levels. 5. Enter values you found in Step 4 into Output Levels fields. 6. Click OK to accept changes you made to highlight and shadow halftone dot values.

35 Black-and-White Tone Targeting 107 Figure 2.16 Or methods to adjust tones of photographs 7. Open Levels dialog box again. 8. Use Gamma Input Slider to decrease midtone halftone dot values by 15% (change a 65% dot to 50%). When you are finished, click OK. Notice that image on screen does not appear as light as it did when you corrected same image for reproduction by flexography. The image appears darker on screen because process/substrate combination of offset lithography on coated paper can hold smaller dots and produces less dot gain than flexography. 10. From File menu, choose Save to save your changes. 11. Close Project2b.eps. Or Methods of Tone Targeting In addition to Levels dialog box, Photoshop provides several or methods to target tones of black-and-white photographs. These additional methods can be found in Adjust submenu of Image menu (Figure 2.16) and include Auto Levels, Curves, Brightness/Contrast, and Variations. Auto Levels Command The Auto Levels command simply applies same Auto function that is found in Levels dialog box. It should not be used without targeting highlight and shadow dot sizes using Output Levels sliders or fields in Levels dialog box.

36 108 C HAPTER TWO Curves Command The Curves command is very important and useful and is covered in depth in Chapter 6. Commands to Avoid The Brightness/Contrast dialog box is deceptively simple and very dangerous. Adjusting Brightness control simply shifts tones up or down scale. The Contrast control stretches tonal range and throws away information in both highlight and shadow areas. Neir Brightness control nor Contrast control attempts to match image to reproduction process/substrate combination. The use of se two controls is not recommended. The Variations command is a very slick and extremely dangerous tool. It is designed for those who say I ll know what I want when I see it. It presents current image along with a number of variations of that image lighter, darker, and so on. However, it relies completely on accuracy of monitor and does not attempt to match image to reproduction process/substrate combination. Its use is not recommended for print reproduction. It works fine, however, if you wish to correct an image that will only be viewed on a computer screen. You will use it for that purpose in Chapter 9. A Start-to-Finish Checklist for Targeting Black-and-White Photographs Using Levels Dialog Box This section serves as a review of processes you should follow when targeting a black-and-white photograph for print reproduction using Levels dialog box. Use this process on grayscale images after lpi and image resolution have been set.

37 Black-and-White Tone Targeting 109 Table 2.7 A recommended process for performing tone targeting using Levels dialog box Step Check 1 Process Find out printing process and substrate that will be used to print job. In particular, find out largest and smallest halftone dot size that can be printed using applicable process and substrate as well as anticipated dot gain. Contact printing department or firm that will produce job. If you cannot get information from printer, use data in Table 2.3 for minimum and maximum halftone dot sizes. Table 4.1 provides examples of dot gain for various process/substrate combinations. 2 Open Levels dialog box. Move dialog box so you can see most of image. Select Preview option, if necessary. 3 Click Auto button. If Photoshop is set to its defaults, a 0% halftone dot will be positioned in highlight density and a 100% halftone dot in shadow density. 4 Use data in Table 2.6 to compress tonal range of image. In highlight Output Level field, type Photoshop tone value that corresponds to minimum highlight dot size you determined in Step 1. In shadow Output Level field, type Photoshop tone value that corresponds to maximum shadow dot size you determined in Step 1. 5 Close Levels dialog box. 6 Add anticipated dot gain to 50%. For example, if anticipated dot gain is 15%, sum will be 65%. 7 Select Eyedropper tool from Tool palette. Watch K: field in Info palette and move Eyedropper pointer around image until you locate an area that measures percent you calculated in Step 6. 8 Write down X: and Y: coordinates of area that you found in Step 7. 9 Open Levels dialog box. 10 Move Gamma Input slider to left to compensate for dot gain by lightening mid- tones. Use Eyedropper pointer to measure location with coordinates you record- ed in Step 8. The New Halftone Dot percentage field in Info palette should read 50%. 11 If New Halftone Dot percentage field reads more than 50%, move Gamma Input slider more to left. If New Halftone Dot percentage reads less than 50%, move Gamma Input slider back to right. 12 Repeat Step 10 until New Halftone Dot percentage field reads 50% when Eyedropper pointer is positioned over area with coordinates you recorded in Step Close Levels dialog box. You have targeted image to be reproduced using printing process and substrate you identified in Step In a production situation, you would now prepare a proof of image by printing it on a laser printer or or proofing device. See Printing Halftones with Photoshop later in this chapter and Proofing and Re-correcting in Chapter 8 for furr information.

38 110 C HAPTER TWO Automating Tone Targeting Using Actions Palette Photoshop 4.0 allows you to automate repetitive tasks by recording a series of actions you take to complete an operation. For example, in Exercises 2.7 and 2.8, you followed a series of steps to target highlight, midtone, and shadow dots. Assuming you have a number of photographs to correct that are similar to each or and will be printed using same printing process and substrate, you can record actions you take to correct first image, n play back those steps on additional images. You can also instruct Photoshop to batch-process all files in a given folder. To access Actions palette, open Windows menu, n choose Show Actions. The Actions palette appears on right side of screen. Its components are illustrated in Figure 2.17 and explained in Table 2.8. Figure 2.17 The Actions palette 1. Actions palette menu triangle 2. Default actions 3. Delete selected item 4. Create new action 5. Play selected action 6. Begin recording action 7. Stop playing or recording action 8. Expand list triangle 9. Toggle dialog box on/off 10. Toggle item on/off

39 Black-and-White Tone Targeting 111 Table 2.8 Components of Actions palette Option Toggle Item On/Off Default actions Delete Selected Items Create New Action Play Selected Action Begin Recording Action Stop Toggle Dialog On/Off Expand List Triangle Actions Palette Menu Triangle Function Check this box if you want a command or action to be executed. Uncheck it if you want a command or action to be skipped. Photoshop 4.0 comes with six prerecorded actions that perform following operations: convert an RGB image to Indexed Color (see Chapter 3 for an explanation of se color systems); Reduce Graininess; create Drop Shadow; create Vignette; open Image Size dialog box; and Revert to Saved. You may need to scroll to see all default actions. If an item in Actions list is selected, it will be deleted if you press this button. Pressing this button will create a new action. A dialog box will appear in which you can name action, assign it to a keyboard shortcut, and assign it a color. Pressing this button causes selected action to be executed. Press this button to begin recording operations you wish to include in an action. To stop recording, press this button while an action is being playing an action that is being executed, press this button. recorded. To stop If an operation contains a dialog box, selecting this toggle (an icon of a dialog box appears) causes dialog box to be displayed while action is running. At that point, you can enter specific data into dialog box before action continues. If toggle is not selected, dialog box will not be displayed when action is played. Any data previously entered into dialog box while action was being recorded will be used. If triangle points down, steps included in an action will be displayed in list. If triangle points to right, only name of action is displayed in list. Pressing this triangle causes a pop-up menu to appear from which you can choose commands. To begin recording an action, click Create New Action button. The New Action dialog box appears (see Figure 2.17). Give action a name and, if desired, assign it to a function key and color. Then, click Record button and perform functions you wish to include in action. When you are finished, click Stop button. To save set of actions so that you may use m for future documents or on anor

40 112 C HAPTER TWO computer, press Actions Palette Menu Triangle n choose Save Actions. You can also use Actions Palette Menu Triangle to load previously saved sets of actions. To use your completed action, you can press function key you chose or select action and click Play Selected Action button. Exercise 2.11 Recording an Action That Will Perform Tone Targeting In this exercise, you will open a new copy of C2exercise.tiff n record operations necessary to perform tone targeting for image in an action. 1. From File menu, choose Open. 2. Navigate to Photoshop Student Files folder, n open C2exercise.tiff ( C2exer.tif) file. Click OK when locked file message appears. 3. Click Create New Action button on Actions palette. The New Action dialog box appears (Figure 2.18). Figure 2.18 The New Action dialog box 4. In Name field, type Target Offset Uncoated. 5. Press Function Key pop-up menu, n choose F2. (If F2 is already assigned to anor command on your system, choose anor function key). Grayed-out F keys are already assigned. Click Shift checkbox. Finally, press Color pop-up menu, n choose Red. 6. Click Record. Notice change in Actions palette. The Record button appears to be pressed and has turned red. The name of action to be recorded is selected and Expand List Triangle points down. 7. From Image menu, choose Adjust, n select Auto Levels. 8. Open Levels dialog box.

41 Black-and-White Tone Targeting In Shadow Output Levels field, type 25 and in Highlight Output Levels field, type 229 ( Output Levels fields in Levels dialog box should appear same as Figure 2.10). 10. Click OK to close Levels dialog box. 11. Open Levels dialog box again. 12. In Gamma Input Levels field, type 1.75 ( Levels dialog box should appear same as Figure 2.12). 13. Click OK to close Levels dialog box. 14. Click Stop button on Actions palette. 15. From File menu, choose Revert. When alert appears, click Revert. The C2exercise.tiff ( C2exer.tif) file returns to its previously saved condition. Exercise 2.12 Using a Recorded Action In this exercise, you will use your Target Offset Uncoated action to perform tone targeting on two images. 1. If necessary, scroll so that your Target Offset Uncoated action appears on Actions palette. 2. Click Expand List Triangle so that triangle points to right (Figure 2.19). This causes only name of action to be displayed in list. Figure 2.19 The completed Target Offset Uncoated action displayed in Actions palette 1. Expand List Triangle points to right when only Action name is displayed. 2. Play Selected Action button. 1 2

42 114 C HAPTER TWO Figure 2.20 The Save Actions In dialog box 3. Make sure C2exercise.tiff image is active; its title bar will ( ) have horizontal stripes in it or ( ) be highlighted if it is active. 4. Click Target Offset Uncoated action on Actions palette to select it. Then, click Play Selected Action button. The prerecorded operations are automatically performed on photograph. 5. From Image menu, choose Histogram. If you have correctly recorded action, data in Histogram field will closely resemble those in Figure Click OK to close Histogram. 7. From File menu, choose Open. Navigate to Photoshop Student Files folder, n open C2exercise2.tiff ( C2exer.tif). Click OK when locked file alert appears. 8. Be sure C2exercise2.tiff ( C2exer.tif) image is active, n press plus F2. Note: You assigned plus F2 to Target Offset Uncoated action when you completed New Action dialog box. If you assigned a different F key, use it instead of F2. The series of actions recorded in Target Offset Uncoated action is performed on photograph. It is now targeted for reproduction on uncoated paper using offset lithography. 9. Press Actions palette menu triangle, n choose Save Actions. The Save Actions In dialog box appears. 10. Navigate to your Photoshop Files 1 disk or folder, in Save Actions In ( File Name) field, type C1actions (Figure 2.20), n click Save. In future you can load same set of actions by pressing Actions palette menu triangle, n choosing Load Actions. Navigate to your Photoshop Files 1 disk or folder, n open your C1actions file.

43 Black-and-White Tone Targeting Close both C2exercise.tiff and C2exercise2.tiff ( C2exer.tif and C2exer2.tif). Do not save any changes. Printing Halftones with Photoshop NOTE To save halftone screen specifications in an EPS file, use following procedure: Open Save dialog box. Press Format popup menu, n choose Photoshop EPS. Click Save. The EPS Format dialog box appears. In Preview popup menu, choose ( ) PICT or ( ) TIFF 8 bits/pixel. Mac users should use TIFF preview option if file is ever to be read by a PC. Click Include Halftone Screen option checkbox to save halftone sceen information with file. Click OK to save file. In practice, few professionals print halftones directly from Photoshop. Instead, y import saved Photoshop files into QuarkXPress, Adobe PageMaker, or or desktop publishing programs and print complete pages. However, you will often find it convenient to print proof or sample copies of photographs from Photoshop to get an idea of what final reproduction will look like. In Exercises 2.13 and 2.14, you will prepare your Project2.eps image for printing and output it on your laser printer or imagesetter. When you have finished, you should compare your results with Figure 2.3. The targeting you have applied during this chapter should result in a more pleasant reproduction than uncorrected version that appears in Figure 2.3. Preparing to Print Photographs Before printing a file using Photoshop, you must set several dialog boxes. You already know that you must set Image Size and Halftone Screen. However, Photoshop provides several or print-related options from which you can choose. These options are only useful when you print an image directly from Photoshop. In most cases, however, photographs are printed from within a page layout program. In such cases, print-related settings specified in page layout program override those used in Photoshop. However, choices made with regard to Image Size always impact quality of photograph. And, as you know, halftone screen specifications set in Photoshop can override those used in a page layout program if photograph is saved as an EPS file and if Include Halftone Screen option is activated. When preparing to print, you must always check Image Size dialog box first. In particular, check size and resolution of image. Then you should choose File Info from File menu (see Figure 2.22). In File Info dialog box, you can include several bits of information about image, including a caption, keywords that can be used to help people find image if it is included in an image library, an appropriate AP (Associated Press) category, picture credits, information regarding origin of photo, copyright information, and pertinent Internet

44 116 C HAPTER TWO bleed Figure 2.21 An example of a photograph that bleeds 1. Edge of printed sheet 2. Edge of sheet after trimming 3. Bleed margin 4. Trim area web page address. Many of se bits of information are most useful for newspaper and periodical publishers. However, you may also find or uses for m. After completing File Info dialog box, Macintosh users should choose a printer using Chooser desk accessory. Both Macintosh and Windows users should n open Page Setup dialog box (see Figure 2.24). At this point, Windows users should choose a printer from within Page Setup dialog box. In addition to options available when using most programs, this dialog box contains nine options and five buttons that open additional dialog boxes. You already know about two of buttons: you need to click Screen button to set halftone screen specifications, and you should avoid using Transfer functions unless you are directed to do so by a service provider. Additional buttons allow you to set a background color when printing to color slides, frame your photograph with a border, and create a bleed (when printing extends beyond edge of trimmed paper [Figure 2.21])

45 Black-and-White Tone Targeting 117 Table 2.9 Page Setup options The nine options that can be chosen from Page Setup dialog box are summarized in Table 2.9 and illustrated in Figure Option Caption Calibration Bars Registration Marks Corner Center Labels Negative Emulsion Crop Marks Crop Marks Down Interpolation Exercise 2.13 Function Causes caption photograph. entered in File Info dialog box to be printed under Prints a ten-step gray scale along edge of photograph. ensure that printer or imagesetter is properly calibrated. Prints targets used by printing technicians to properly align images. Prints marks photograph. It is used to at each corner of image that indicate edges of Prints marks at center of each side of and vertical centers of photograph. image that indicate horizontal Prints name of document and channel name on page. Prints a negative image of photograph (blacks become white and whites become black). Do not use this option unless instructed to do so by a service provider. Tells an imagesetter on what side of a sheet of film to place use this option unless instructed to do so by a service provider. image. Do not This option improves printed appearance of low-resolution images. Use this option only if output laser printer or imagesetter is equipped with PostScript Level 2. Preparing an Image for Printing Using a Laser Printer In this exercise, you will prepare Project2.eps for printing by making entries in several dialog boxes. 1. From Image menu, choose Image Size. The Image Size dialog box appears. Notice that file is 58K in size, its dimensions are 4" 2.847", and that it has a resolution of 72 ppi. 2. Deselect Resample Image option (re should not be an x in its checkbox). 3. Click Auto button.

46 118 C HAPTER TWO NOTE You will notice that in this exercise you will repeat several processes you learned in Chapter 1. You should always follow a sequence of steps to insure that image you output will be a quality photograph and have halftone attributes specified for job. In particular, it is absolutely necessary that you always check and set Image Size dialog box before printing any photograph. Figure 2.22 The File Info dialog box 1. Choose a section from this pop-up menu 2. Enter a caption of up to 2,000 characters in this field 3. Enter name of caption writer in this field 4. Enter a Screen frequency of 50 lines per inch, n click Good Quality radio button. Click OK. Examine Print Size information at bottom of dialog box. Notice that Resolution has changed to 75 ppi (remember that you chose a 50 lpi screen and that checking Good Quality radio button multiplies lpi by 1.5 to establish ppi resolution) and that Photoshop had to decrease dimensions to 3.84" 2.733" because re was insufficient data in file to maintain original image dimensions and provide a resolution of 75 ppi. 5. Click OK to close Image Size dialog box. 6. From File menu, choose File Info. The File Info dialog box appears (Figure 2.22) Press Section pop-up menu at top of dialog box. Notice that it allows you to enter six different categories of information about photograph. Choose each section from pop-up menu one at a time and look at dialog box that appears when each section is chosen. When you are finished looking at all six dialog boxes, choose Caption from Section pop-up menu. 8. In Caption section type Natalie Jones wins makeup contest at YWCA competition! In Caption Writer section, type your name. Then click OK. The File Info dialog box closes.

47 Black-and-White Tone Targeting 119 NOTE The lpi is set low for two reasons: 1) file has too little data to reproduce photograph using a higher resolution; and 2) we assume you are using a laser printer to print file. Fifty lpi is about maximum se printers can accommodate (see Table 1.4 on page 43). If you have a 300 dpi printer, you may wish to specify 38 lpi. 9. From Apple menu, choose Chooser. Use Chooser to select a laser printer that has 300 to 900 dpi resolution. Check with your instructor, trainer, supervisor, or lab assistant if you need help with this step. Close Chooser. Skip to Step From File menu, choose Page Setup. The Page Setup dialog box appears. (Macintosh users: If your computer is running Apple Laserwriter 8.4, you must press pop-up menu labeled Page Attributes and choose Adobe Photoshop 4.0 to see Photoshopspecific Page Setup choices.) From File menu, choose Page Setup. The Page Setup dialog box appears. If necessary, click Printer Name drop-down arrow, n select a laser printer that has 300 to 900 dpi resolution. 11. Click Screen button. Deselect Use Printer s Default Screen checkbox, n set screen to 50 lpi, 45, ellipse shape. Click OK. 12. Click Border button. The Border dialog box appears. Type 2 in Width field. Select points if necessary (Figure 2.23). Click OK. Figure 2.23 The Border dialog box 13. Select all of following options: (Note: The following list assumes you have a PostScript printer. If not, some of options may not exist or may have no affect.) Caption Calibration Bars Registration Marks Corner Crop Marks Center Crop Marks Labels Your dialog box should look like Figure 2.24.

48 120 C HAPTER TWO Figure 2.24 The completed Page Setup dialog box Table 2.10 Print dialog box options 14. Click OK to close Page Setup dialog box. 15. Save your changes. Printing Halftones After working your way through necessary steps to prepare a photograph for reproduction, actual printing process will be relatively easy. You are given several choices in Print dialog box, however (see Figure 2.25 and 2.26). The options are listed and described in Table Option Function C opies Enter number of copies you want, up to 999. Pages Paper Source Destination Print Print Selected Area In Encoding Options In contrast to page-layout files, Photoshop files do not have more than one page. Therefore, you should ignore All, From, and To options. If your printer allows you to choose to print from more than one source of paper, choose type of paper you want from this pop-up menu. You can eir print to a printer or to a PostScript Print File. You should to a file unless specifically instructed to do so by a service provider. not print If you have a portion of image selected, you may choose this option to print only selection. You can use this option to print an image to more than one sheet if it will not fit on one page or to quickly print a copy to check impact of changes that you have made to an image. If Photoshop is displaying a color image, additional choices become available. For example, you can choose to print a color image in black-and-white or to print a separate sheet of paper for each color (separations). Choose Binary unless your printer or network cannot handle binary-encoded files. ASCII files take much longer to process. Do not use JPEG for print reproduction due to lossy scheme that is employed when se files are compressed. When using Photoshop, re is no available by clicking this button. need to use system-level print options

49 Black-and-White Tone Targeting 121 Exercise 2.14 Printing a Halftone Using a Laser Printer In this exercise, you will print Project2.eps, n inspect finished reproduction. 1. From File menu, choose Print. The Print dialog box appears (Figure 2.25). If you are using Laserwriter 8.4, you must press pop-up menu labeled General and choose Adobe Photoshop 4.0 to make some settings. Figure 2.25 The Print dialog box Macintosh From File menu, choose Print. The Print dialog box appears (Figure 2.26). Figure 2.26 The Print dialog box Windows 2. Choose following options: Copies: 1 Destination: Printer Encoding: Binary (on Adobe Photoshop 4.0 page of Apple Laserwriter 8.4) Paper Source: Check with your lab assistant, trainer, supervisor, or instructor. 3. Click Print ( OK). The photograph will now print. 4. Compare your printed copy with one appearing in Figure 2.27.

50 122 C HAPTER TWO Notice following items: two types of Registration Marks Label (name of file) at top 2-point Border Corner Crop Marks Center Crop Marks Calibration bar Caption Figure 2.27 Printed copy of Project2.eps Two types of registration marks 2. Label 3. 2-point border 4. Corner crop marks 5. Center crop marks 6. Calibration bar 7. Caption Look at child s face on your printed copy. Compare your print with image in Figure 2.3. Notice following about your copy: The shadows are lighter than those in Figure 2.3 The midtones are lighter and provide more detail than midtones in Figure 2.3 Your reproduction looks better overall than Figure Compare your printed copy to image on screen. Notice how printed version appears much darker than image on your screen. The dot gain inherent in laser printers, as well as most printing processes, causes midtones to appear darker on print than on screen.