Workflow for Betterlight Imaging

Transcription

1 Workflow for Betterlight Imaging [1] Startup Check that camera lens shutter is fully open Check lens is set to F stop 11 (change by manually adjusting lens aperture ring) Check Infrared (IR) Absorbing Filter is securely mounted to front of lens in filter holder Remove lens cap from camera lens Turn on stabilizers Turn on Tungsten lights with foot switches (4 lamp setting, switch between 2/4 at back) Turn off overhead lights Turn on Better Light control unit (flip silver switch to up position) Turn on computer Open Viewfinder software Add copyright statement by clicking the I icon and type or past simple text [2] Set LINE 1/60 of a second and set 300. This will be a reasonable starting point for the first test prescan and can be adjusted later NOTE: Line time and ISO base settings are optional starting points. If working on multipage object, recommend to use settings from last good scan. Click on the Tone Curve Panel and verify the curve Repro 2.2 is selected from the menu. Resolution NOTE: This will be the starting point to optimize the tone reproduction of the scanned subjects. Do NOT move the position of the circle handles on the curve unless you intentionally want to modify the tonal reproduction. (optional) Place background paper on copy stand [3] Position art in center of scanning area [4] Verify art is level Measure the physical dimensions of the item In the ViewFinder software: Enter or modify desired File Name [5] Select SIZE tab Set ppi to 300 Make a Fast Prescan of item Adjust the Crop Area to fit the image with a thin border Determine if image dimensions are a close match to physical dimensions Adjust image size by changing the resolution % setting or repositioning the camera head o If repositioned camera head will need to re prescan to confirm size adjustments

2 Focus Select FOCUS tab panel o Check that slider is set to 8x (magnification setting) o Check that only green channel is active Focus target If using focus card, o Place card towards the edge of content (not in center) and on same plane as the object (not above glass, if using a glass overlay or the book cradle ) o Make a normal Prescan of item (this will update image for focus card) o Place cursor over the focus card in such a way that the cursor is perpendicular to fine lines on the card and click to point target for focus OR A high contrast area on the subject matter can also be used as a focus target o Place focus pointer at a high contrast area of image AND o at high elevated point in the image (follows 1/3 above, 2/3 below rule primarily usefully for non flat materials) Press the GO button o This provides a live reading of contrast [6] o Click the Zoom button to enlarge the panel display of the focus readings Slowly adjust the camera focus knob to get to the highest number possible Press STOP when highest value is obtained Verify focus using SuperView function at all 4 corners of image NOTE: check focus at full resolution (100%) Sample using the SuperView function. A Fullresolution sample in this case is indicated in the software at the bottom left corner of screen. The area sampled (aka red box) will vary with the resolution setting. Click and drag the red rectangle to the area you wish to inspect at full resolution. If focus is still poor o First try re sampling a slightly different focus area and repeat steps above o Otherwise may need to physically adjust camera head height and repeat steps. Important note: If adjust camera head position, will need to also recheck the image size and resolution settings and adjust if necessary 2 P age

3 Exposure, Tone and Color Balancing Goto TONE Tab Verify Repro 2.2 v2 tone profile is selection [7] Make a normal PRESCAN not FAST Prescan Goto COLOR Tab Panel Verify color custom profile is selection: BetterLight_SG_Feb2010 Place Macbeth ColorChecker in center of document and on same plane as material. NOTE: The white patch of the color chart should be placed in the brightest area of the image to assure the most accurate exposure Place the SPOT METER Circle in the middle two gray squares Press AUTO BALANCE button. This will remove any color cast from the image caused by the color character of the lighting Clear the Meter Spots with button on panel, menu bar, or use the keyboard shortcut (Command+M) Place a SPOT METER Circle on the white square of the Color Checker Observe the green RGB value and Validate value is in range of 235 to 245 [8] If white value is not in range, adjust Line Time and/or ISO settings [9] Clear spots meter Click on Tone Zone icon located on the top toolbar o Histograph window will show up Select over/under exposure profile Observe spread of light as indicated by tone zone profile. Red colored areas indicate blown out section (overexposed areas) which will want to reduce. Orange is borderline for over exposure, may be able to adjust in photoshop if area is in border of image. Adjust ISO setting to avoid blown out sections but watch out for underexposing entire image. Find a best comprising for image NOTE: The BEST exposure conditions are always the SHORTEST Line Time and LOWEST ISO settings. TIP: once exposure is determine, can lock LineTime/ISO combination and then adjust for time of scan Remove focus card and Macbeth ColorChecker Make another prescan to verify cropping, size and resolution settings remain as expected If all is okay, then press SCAN button Final image should open up directly in Photoshop (per setting options in Preferences) 3 P age

4 Final quality assessment In Photoshop, visually check sharpness, brightness and tonal contrast o View image at full resolution (100%) when checking focus o Check focus at each corner Review for any scanning flaws such as poorly cropped image, distortion or blemishes that obscure the legibility of page that are due to the photo processing (i.e. blemish is not part of the original text) and any glare from protective covering is minimized) Rotate page image(s) to their proper orientation Check the squareness of artwork o Use the Grid view or Guide Lines to determine straight line (view>show>grid) or pick straight edge from image itself o Use ruler tool to straighten image. Analysis>Ruler tool> Drag mouse along straight edge Image>rotate>arbitrary and Press ok Apply mild sharpening with Unsharp Masking. (Filter>Sharpen>Unsharp mask. Suggested settings: 150% 300% at 0.4 Radius with 0 Threshold) Crop image to desired size (optional) Save edited file to project folder location NOTE: Be sure all quality requirements are met before proceeding to next scanning subject. The Next Image For consecutive pages from the same item, may use same scan settings. Place the next piece of art as close to the same position as the previous one Make a Prescan Check positioning and cropping Check resolution settings Check exposure with Tone Zones Check focus with super view tool (optional or at every 15 pages) Press the SCAN button. TIP: Best to start with largest pieces and work down to smaller ones to minimize the moves of the camera and lights. If next image is significantly different from prior scan, best to start from beginning. 4 P age

5 Additional practices for books, bound materials or other multipage objects: Goal is to ensure consistency of overall tonal quality across multiple pages. Note settings of original scanning conditions in order to duplicate for future scanning sessions (ie f stop, camera head position, ISO/LT, RGB values, size) Re calibration: may require manually adjustments during any individual scanning session back to original conditions o Match lighting settings and camera head position during entire job o Match color/tone settings as closely as possible (RGB, ISO, size) through entire book (this may require manually adjusting RGB values directly rather than simply using spot meter and auto balancing) o Recalibrate color/tone settings if any single page is visually distinct from adjacent pages (such as color illustration vs textual page) o Re check focus every 10 to 20 pages (4 corners rule applies). When scanning large books, even when using the book cradle, individual pages may become unlevel (which impacts overall focus) as move deeper into book. Check filenames are not mislabeled (eg file names should match printed numbers on original or follow sequence of actual page order) Check for completeness o Scan image includes border w/ edge of document (ensure that no cropping of image itself has occurred) o Scan the complete document including reverse side of pages, front and back matter, blank pages, hard coverings, spine, etc. Perform visual comparison of digitized images with original document. Reduce manual handling of fragile materials by scanning all facing pages, then flip book to scan rest (eg all odd, then all evens pages) When continuing a scanning job between days, open several previous scans from the same item. First scan of the work session compare tonal quality to the adjacent pages from prior scanning session. TIP: note down what settings were used in prior scans (including camera position) as these will help with starting point for next scan NOTES [1] Workflow is based on presentation given by Larry Guyer and Mary O Connor during on site training session, Feb 17th, 2010, various online betterlight literature, and in house practices [2] User Notes are limited to 255 characters in total. User notes contain the filename, along with other image exposure information such as line time, scan area, color balance, etc. Exposure information is automatically recorded with each image. User Notes are embedded in Tiff header. 5 P age

6 [3] Background paper is usually a large black sheet when the intention is to capture a surrounding border in the image. Alternative colored poster boards may be more appropriate when capturing semitransparent paper (eg onion paper). Extra poster paper may be found in box case. [4] For guidelines on handling archival materials, see p26. [5] Note that for Betterlight scanning, the maximum filename length is limited to 63 characters but most computer operating systems will only allow the first 31 characters as a file name. See best practices for determining file p8. Check with project manager for local guidelines. [6] The focus knob is located on the camera head to the right of lens and must be manually adjusted. In the viewfinder software, the focus window will have three (3) ways to indicate focus Turn the focus knob of the camera and observe: a. A green line will go from left to right as focus improves. b. A box with arbitrary numbers will count up or down as you turn the focus knob. When you reach the highest number you re in focus! c. A wavy line display (that looks like a heart monitor) will get sharper peaks as the focus improves. There is no perfect number it is relative to the focus target contrast and magnification. When there has been a large physical change in camera head position from previous setting, may need to make a corresponding large adjustment to bellows by manually adjusting knob heavily. Can also perform a rough focus directly from camera position by gently removing CCD insert and then inserting ground glass panel. The image will be upside down and backwards. May be helpful for when there is a great change in camera positions between two scans. Careful handling of CCD is strongly recommended. [7] Additional local corrections in highlights, shadow or midtone values can be made by click dragging on the round handles of the Tone Curve, much like Photoshop curve adjustments. Such manual tone curve adjustments can also be used to refine contrast for 3D imaging. [8] Green RGB value: Best practice is to use the CENTER Green channel to make judgments for focus accuracy, color and tone balance. The green channel holds the most image detail visible by human eye and is therefore the most reliable to base judgments on. [9] Though the ideal white value for the Repro 2.2 tone curve is approximately 243, we have found in local practice that the Tungsten lights tend to run hotter and 243 may result in overexposure. Values closer to 235 seem to produce better visual results. 6 P age