FLAAR Reports. Color Management with MonacoPROFILER. Digital Imaging, Software, Media, and Inks DECEMBER 2002

Transcription

1 FLAAR Reports Digital Imaging, Software, Media, and Inks DECEMBER 2002 Color Management with MonacoPROFILER

2 By Charles Spontelli Bowling Green State University College of Technology Color Management with

3 1 The goal, or holy grail of color management, is to have control of color images from capture, to editing (viewing on the monitor), to final output. Simply put, we want our monitor image to look like our printout. And, we want our print to be beautiful. That being said, we all know that beauty is in the eye of the beholder. So, as helpful as color management can be in creating beautiful color images, there is a lot of subjectivity in the process. The problem that color management and was created to solve largely relates to the device dependent nature of how we work with color. A typical imaging system consists of a number of interconnected devices, each creating or recording color in its own unique way. Digital cameras or scanners all record color is RGB. But shoot the same scene with a different camera or scan the same original with a different scanner and you will get different results. All RGB is not created equal. CRT Monitors use RGB phosphors to display our captured image. Again, different monitors and settings yield different looks with the same image file; the reason, device dependence of the color. Finally, the printout. Most printing devices, except film recorders, use CMYK dyes or pigments in their inks or toners. Even though they all print with CMYK, some require RGB files and other CMYK image files. Print the same file to different printers and, you guessed it, different results. So, as color passes from one component of our imaging system to another, each device interprets that color information in its own way. The result, to quote Albert Munsell, is color anarchy. Each device doing it s own thing as far as color is concerned. The solution that color management provides is to provide a common device independent language to communicate color from one device to the next. The most common language in use today (and used by Monaco) is the CIE LAB color model. Based on human color perception, two colors with matching lab values will be seen to match by a human observer (under a common light source). The CIE LAB System does not depend on any device to define a color. The same LAB value looks the same no matter which device its on. The key is to get arbitrary device dependent colors translated to LAB color values. This is done with color profiles.

4 2 Color profiles are what connect arbitrary device dependent color values to LAB device independent values. Monaco Color Profiler makes profiles. Each device in our imaging system requires its own profile to translate its proprietary colors into the Standard LAB. Scanners and digital cameras, monitors, and printers each need a unique profile. provides four software packages in one. Some profiling software only profiles one type of device i.e. monitors. Monaco Scan enables you to build custom input profiles for scanners and digital cameras. Monaco View allows you to calibrate your monitor and produce a unique monitor profile for your viewing conditions. Monaco Print allows you to build custom profiles for your printer-media combination. Finally, Monaco Tweak allows you to adjust profiles after you create them. Remember, there s a lot of subjectivity in the color imaging process. To do all of this profiling requires that you have some color measuring instrumentation. You ll need a colorimeter and/or a spectrophometer. These devices will allow you to measure colors in LAB space. The most popular devices are available from XRITE (Dtp 92 colorimeter and DTP41 spectrophometer) and Gretag-Macbeth (spectrscan/spectrolino).

5 Color Management with MonacoPROFILER By Brent Cavanaugh Bowling Green State University, Center for Applied Technology, Large Format Digital Imaging Division, Lab Manager

6 1 Color management is a key component of any printing operation. Changes in types of media and ink will affect the color output of a printer. Some of the large format printers on the market are equipped with onboard cameras or sensors for basic linearization of the density of each ink being laid down. Linearization will get the printer s output to a known average point, but will not tweak each individual color to a known value. The HP Designjet 5000PS has a camera for such linearization. Printers such as the Colorspan Displaymaker Mach 12 and Series XII have cameras for both reading color patches for linearization and building internal profiles. The Colorspan printers are the exceptions to the norm. For most printers outside software and measuring devices must be used to create output profiles for large format inkjet printers. Building a profile involves the printing or scanning of known color patches, careful measurement of these colors. These measurements are compared to what the values should be. Transforms are created as key components in the profile to adjust colors that did not print correctly. saving. Software for building profiles is written to help you step through the process and do the calculations for you. These packages will allow various levels of control and adjustments to the process. One of the major suppliers of color management software is Monaco Systems. Founded in 1993, Monaco has supplied many color adjustment and management products for the burgeoning home printer and scanner market, as well as the professional printing industry. With the development of the International Color Consortium (ICC), Monaco has been marketing color management software for both the home user and the professional. In fact, MonacoEZcolor is bundled with many OEM printers and scanners today. Monaco has a package called MonacoPROOF for Professional labs and print shops needing full color management capabilities. It is currently only available on the Mac, but a PC version is in development. This software creates input and output ICC profiles, monitor profiles. It provides editing tools for further adjustment of ICC profiles. The package does not include a spectrophotometer (device for precisely measuring the quantity of light at specific points in the light spectrum) or a colorimeter (measures the quantity of red, green and blue light), but is compatible with a wide variety of devices on the market. The Monaco web site lists the following supported devices and targets: Device Support for Output Profiling* X-Rite DTP41 spectrophotometer series X-Rite Digital Swatchbook spectrophotometer Spectrostar Spectrocam spectrophotometer GretagMacbeth Spectrolino spectrophotometer GretagMacbeth SpectroScan spectrophotometer and x/y table

7 2 Target Support for Output Profiling* MonacoProfiler Targets up to 2956 Patches IT8.7/3 Extended Target (for use with GretagMacbeth SpectroScan only) GretagMacbeth Eye-One spectrophotometer Device Support for Monitor Profiling* MonacoSENSOR colorimeter (CRT only) X-Rite DTP92 colorimeter (CRT only) GretagMacbeth Eye-One spectrophotometer GretagMacbeth Spectrolino spectrophotometer Target Support for Input Profiling Reflective IT8 Target (included) Kodak, Fuji, and Agfa Reflective IT8 Targets Kodak, Fuji, and Agfa Transparency IT8 Targets HutchColor Transparency Target GretagMacbeth ColorChecker DC Color Reference Chart * Contact Monaco Systems for information on purchasing supported measurement devices. ** Contact Monaco Systems for information on purchasing transparency IT8 targets. Through Dr. Hellmuth and FLAAR the Large Format Digital Imaging Lab and professors at Bowling Green State University have obtained a copy of MonacoProfiler courtesy of Monaco systems for evaluation on the equipment of the lab and the Visual Communication Technology department at BGSU. We have used the MonacoProfiler software to build profiles for the Cruse CS 155SL Synchron Light scanner and the HP Designjet 5000PS printer, as well as other printers in the College of Technology. Unfortunately, we were unable to test the monitor profiling in the lab at this time because the Spyder colorimeter we currently use is not currently compatible with the software. The VCT program at BGSU has a GretagMacbeth Spectrolino spectrophotometer which can be used for monitor profiling but we have not been able to test with it yet. We hope to follow up with an update. The installation process of MonacoProfiler is a simple step by step process. The software does use a USB dongle or hasp for copyright protection. The dongle must be in place for the software to operate.

8 As you proceed with the use of the software the program will walk you through the steps required for building profiles. One of the hardware issues we encountered was with connecting the XRite DTP41 spectrophotometer. Because the newer Mac s only use USB ports for connecting devices, we needed to use a KeySpan adapter to convert the serial cable for the DTP 41 to USB. The KeySpan adapter generally works well although the ports sometimes have to be reset in the control panel for the KeySpan to recognize the DTP41. The KeySpan also cannot be operated from the USB port on the keyboard. Input Profiling Color management begins with the input profile. MonacoSCAN is the component of MonacoPROFILER that will build input profiles. The input may be coming from a digital camera or from a scanner. To be able to build a profile you must have a standardized target to scan. This target will have a data file that provides precisely measured information about each color on the target. The software building the profile uses that data to compare to the file created of the target. From that comparison it is able to characterize or profile the input device. As ICC profiling has developed industry standard targets have been developed specifically for building input profiles. The IT8 target is the industry standard of creating input profiles. Monaco provides an IT8 target produced by Kodak. It is referred to as the Q-60 target. The target has a date stamp on the bottom left that will refer you to the proper data file to select to match the target. In the case of our target it reads: IT8.7/ :02 The first line refers to the standard for creating the target. The second line refers to the manufacture date. The data file is supplied by Monaco, but if you did not have the correct data file it could be downloaded from the web sit of Monaco or Kodak. There are two methods for creating the input profile with MonacoSCAN. The first method lets MonacoSCAN launch the scanner plug-in and capture the scan directly. Most scanner come with Twain drivers or with Photoshop input plug-in programs such as Silverfast. The plug-in must be compatible with the MonacoSCAN and your computer must be attached to the scanner. In our case, this method would not work for us since the Cruse scanner is attached to a PC. The second method involves scanning the IT8 target with the software for the scanner and loading the saved scan afterward into MonacoSCAN. This is the method we used. One important point to remember is that you must continue to use the same settings in the scanning software for normal scanning as you used in creating the profile for the profile to be accurate. Many of these packages will have controls for adjusting the scan. You need to adjust these settings then save them so they can be used again. 3

9 The Cruse scanner uses SilverFast HDR version 5.2 for adjustment of the image before saving the file. This program will allow you to open a raw scan and adjust the image before exporting it to Photoshop. We use the default settings in the software and saved the settings so they could be reloaded before each scan. Many of the scanning software packages will allow you to apply the input profile to the scan as it imports it into Photoshop. Version 5.2 of Silverfast does not allow you to apply ICC profiles as it exports the image to Photoshop. However, in Silverfast HDR version 5.5 additional color management controls will allow you to apply an input profile on export. So, in our case we will be able to build a profile but not able to apply it until after it enters Photoshop. Using the Cruse we scanned the IT8 target and using Silverfast with default settings opened the scan in Photoshop. It is important for the target to be clean and free of dust for the best scan and subsequent profile. The image was sized and cropped to around 5x7 at 200 PPI. The file was saved to disk and taken to the Mac with Monaco installed. After launching MonacoPROFILER and MonacoSCAN, you choose the reference file for the IT8 target you scanned, load the image file of the target, crop it and create the profile. Similar steps are used for creating profiles for transparency scanners and digital cameras. The program will give you a warning if the scan is too different from what the data file says the each color should read. If you receive such a warning check the settings used in your scanner software and adjust if necessary. Remember to save the settings again. Output Profiling The ability to predict color reproduction and match colors is an important part of any lab s operation. MonacoPROFILER provides simple but quality tools for creating these profiles. MonacoPROFILER will step you through the simple process for creating profiles. There are some points to keep in mind when going through this process. Remember to calibrate your measuring device before starting so it will be in a known state. Make sure you have calibrated the printer with the tools it provides recently. Turn off any auto correction or color management options on the printer that may interfere with correctly printing the targets. You will want to take careful notes of all the variables for creating the profile so you will be able to refer to them when problem solving or creating profiles for other media. MonacoPROFILER allows you to create profiles for both RGB and CMYK output devices. Most inkjet printers will need CMYK profiles even though they may have built in RGB emulation. For example, the HP Designjet 5000PS has default CMYK profiles provided for each of the HP medias compatible with that printer and ink combination. These profiles are generally very good, but if you want to use another manufacturer s media you will need to create your own profile specific to that printer-ink-media combination. 4

10 Linearization is the first step in creating a profile. It will measure the amount of each ink being delivered by the printer and adjust the amount to what was really called for by the software. This gives a better starting point in the profiling process. The number of patches to read can be adjusted. You can print directly through the Monaco software if you are using the Postscript driver in applications to print.if you print from a RIP you can save the targets as a file for printing. Remember to allow for proper drying time of the ink. It is best to be consistent in the amount of drying time through all testing. After printing and reading the linearization patches the program proceeds with the color patches for profiling. The directions from the manual and on screen are very clear and helpful. Output profiles can be linked through MonacoPROFILER to help make the output from two printers match. This is especially helpful if you have a proof printer you need to match to the final printing press. Profile Editing Comparisons MonacoTWEAK is another portion of the package that allows you to adjust already created profiles. With this software you will be able perform color edits to profiles to tune them for precise color matching. The screen can display before and after images so you can see the changes made to the profile. Several tools are incorporated for adjusting color output including lightness and saturation adjustment, curve adjustment and selective color adjustment. MonacoPROFILER is similar to other packages on the market. I have worked with Kodak s Colorflow, XRite s Colorshop and GretagMacBeth s Eye-One Pro. Colorflow, Colorshop and MonacoPROFILER are very similar products with the same basic functionality. The differences between the software of the programs are more apparent in the look and feel of the programs. The process of profile creation is very similar between all three. Although I have not yet done direct comparison profiles, I would assume the algorithms for creating the profiles are of similar quality. Kodak s Colorflow has had a lot of development for using RGB output with their printers and with dealing with color negative film. If this was your primary interest this may be a better product for you. The software can be sold as individual pieces of software (Monitor Profiler, Profile Editor, Input Profile Builder, and Output Profile Builder) or as a turnkey solution including hardware. 5

11 Another consideration will be device compatibility. If you already own a spectrophotometer or colorimeter you will want to be sure it is compatible with the software. Colorshop is only compatible with XRite s measurement tools. One of Monaco s best selling points is compatibility with many different measuring devices. The GretagMacBeth Eye-one software is a very nice package with an excellent graphical interface. It is limited to the hardware supplied by GretagMacBeth. Conclusion MonacoPROFILER is an excellent package for complete color management. Its flexibility in using several companies measuring devices is a great benefit, especially if you already have one of the devices. The software is complete and easy to understand and use. The documentation in the manual is well written. More information is available on their website, www. monacosystems.com. Monaco s long time commitment and experience in color management and wide use with OEM products prove its quality and respect in the industry. I would recommend downloading the literature and demos of the color management programs listed above to see how comfortable they are for your uses. Because of the expense of the software and devices I would also recommend contacting each manufacturer for users in your area you can contact for further information. 6 List price of $ C L I C K H E R E T O VIEW EACH FLAAR NETWORK SITE Please realize that all reports are in Adobe Acrobat PDF format. The reader software is free from PDF files are intended to be read on your computer monitor. Naturally you can print them if you wish, but if the photographic images within the reports were high enough dpi for a 1200 dpi laser printer it would not be possible to download them. So the images are intended to be at monitor resolution, naturally in full color. FLAAR itself makes the files available only in PDF format because that is the international standard. We have no mechanism to print them out and mail them. Obviously if you have d handle a basic PDF file. Propietary rights notice Copyright FLAAR Network 2002, first issued December 2002