Color Management for Digital Photography

Transcription

1 Color Management for Digital Photography A Presentation for the Akron Camera Club By Tom Noe Bonnie Janelle Lou Janelle

2 What Is Color Management? An attempt to accurately depict color from initial camera capture, through post-processing, and finally to the desired output, whether it be screen or a print Involves two or three vital steps: Use of a color target during initial capture / Creation of an ICC profile for each body/lens/light source combination Post-processing on a calibrated monitor Use of ICC profiled printer/paper

3 Is Color Management For Me? Color management is vital for photographers seeking: Exact color match between original subject and final image (catalogs, product photography, food photography, still life) Portrait photographers seeking exact skin tone matching Color management may not be vital/viable for photographers doing: Landscapes, sports/action, animals/birds If you simply don't want to bother

4 Commonly Used Terms & Definitions in Color Management

5 1. Color model: A method of turning color into numbers Examples: RGB, CMYK, LAB, XYZ, PAL, NCTS

6 CIE Color Model (Commission Internationale de l-eclairage) Color model based on human perception

7 Cameras Use RGB Color Model State the desired goal Define the goal in more detail

8 Printers use CMYK Color Model Give a summary of the current situation

9 2. Color Space: A specific way to implement a color model Examples of Color Spaces within the Color Model of RGB: srgb, RGB 1998, Pro Photo

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11 3. Gamut: Colors encapsulated in a color space 4. Clipping: Colors outside the gamut of a color space

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13 Why Photo Labs Like srgb! Summarize the main plans Explain the long-term course to follow

14 5. Color profile: A numeric model for programs & operating systems to define color within a color space.

15 The Importance of Color Profiles Proper Color Management REQUIRES image files to have embedded profiles This is so that the device understands the color to be defined. Web Resources:

16 The Color of White Human eye automatically resolves what is white Digital sensor cannot automatically resolve white Let the camera try and figure it out Tell it specifically what value to use White is determined by color spectrum of light Illuminant a light source that has been measured or specified formally in terms of spectral energy Illuminant A tungsten light Illuminant D D50 and D65 represent natural daylight Illuminant F F2 through F12 represent fluorescents

17 Color Management Tools For camera capture: X-Rite Photo ColorChecker Passport ( X-Rite Photo ColorChecker Classic ( MacBeth ColorChecker Card ( ) For monitor calibration: X-Rite Photo ColorMunki Display ( X-Rite Photo i1 Professional Solutions (

18 Calibrating Your Monitor Before you begin: Let monitor warm up for several minutes Turn off extraneous sources of bright light Clean the surface of the monitor (at least where you'll be measuring) Change to the resolution where you'll be viewing/editing images Begin the calibration: Attach calibration device (usually via USB) and start calibration software Skip simple mode, select D65 as your illuminant and a Gamma of 2.2 (these are the defaults)

19 Calibrating Your Monitor During the calibration: Ensure that the device lies flat against the monitor Have a flashlight ready to adjust the brightness of your monitor (it's hard to see monitor buttons in the dark) Have patience it takes 5 minutes to run the test. After the calibration: Give the profile a date-based name so that it will be unique (especially important on Win 7/8 machines) Toggle between uncalibrated and calibrated to see the difference. First time will usually be dramatic difference. Set up the software's alarm to remind you to re-calibrate as often as you wish.

20 Capturing The Color Target Capture a properly exposed ColorChecker target for each sensor/lens/light source combination Properly Exposed? White square should not be blown out Black square should not be underexposed For white square, increase exposure until the square is blown out, back off exposure by 1/3 to 2/3 stop. Once proper exposure is achieved, turn ColorChecker over and do a custom white balance

21 Working in Adobe Lightroom Once images are imported into Lightroom, find image of properly exposured ColorChecker card Attempt to send image directly to ICC profile builder by using Export with preset ColorChecker Passport or by simply exporting as DNG file Export with preset attempts to use the same filename over and over again bad if you want to start building a library of ICC profiles Export as DNG allows you to control the name Either way, you'll need to leave and restart Lightroom

22 Working in Adobe Lightroom Once the profile has been created and Lightroom restarted, go to the Develop module and look in the Camera Calibration area on the bottom right side Click on Profile and a dropdown list will appear showing all of the available camera profiles. Simply select the one you want and it will be applied. At this point, the image should now be color corrected and you can finish applying image changes.

23 How to set up the Adobe.dng profiler This Youtube video describes the procedure:

24 Meet Tom Shot: Raw, ISO 400, Exposure = 1/250 sec at f / 8.0, focal length = 140 mm, flash, lens = mm f / 2.8

25 Using A Color Checker and a Color Balance Adjustment Layer in Photoshop Before: After:

26 Printing Workflow Guide (adapted from an article written by Diane Miller for Adorama, April 11, 2011)

27 What you see on your monitor will never exactly match what you see in your print. The goal is to make sure that the monitor and the print reflect, as accurately as possible, the information that is contained in the digital file. Diane Miller / Adorama

28 ICC Profiles Monitor Printer

29 In color management, an ICC profile is a set of data that characterizes a color input or output device, or a color space, according to standards promulgated by the International Color Consortium (ICC). Profiles describe the color attributes of a particular device or viewing requirement by defining a mapping between the device source or target color space and a profile connection space (PCS). This PCS is either CIELAB (L*a*b*) or CIEXYZ. Mappings may be specified using tables, to which interpolation is applied, or through a series of parameters for transformations.

30 Monitor Types CRT / RGB limited color space LCD backlit by CCFL (cold cathode fluorescent lamp) tubes 6500 K color temperature srgb color space RGB LED backlit LCD monitors are high-end products targeted for advanced professional graphics use, with color gamuts significantly wider than Adobe RGB. They are expensive and are often sold with their own profiling software and colorimeters. White LED backlit LCD monitors are targeted for home and office use and are brighter than previous generations of CCFL LCD displays. They employ colored LEDs filtered with a dye of the complementary color to emit white light.

31 Monitor Line Viewing Angle of sight should be perpendicular to the monitor.

32 Brightness Newer monitors are much brighter and need to be adjusted to balance room light.

33 Apple imacs, MacBooks and Cinema displays present a problem with luminance adjustment. In order to adjust white luminance it is necessary to use the ColorEyes Display Pro software, which I understand can interface with the Apple video hardware. None of the other calibration packages have this capability. Diane Miller / Adorama

34 Gamut (Color Space) Camera srgb (JPEG) Adobe RGB (raw) ProPhoto RGB (raw) Monitor / Software Program srgb Adobe RGB ProPhoto RGB Printer srgb Adobe RGB

35 Monitor Calibration Packages Datacolor (the Spyder series ) X-Rite (the i1 series, PANTONE Huey and the ColorMunki) Integrated Color (ColorEyes Display Pro).

36 Printer Print Calibration from Photoshop (or Lightroom) Use the ICC profile that matches printer and paper (available from the paper supplier as a download) Use soft proofing from within Photoshop or Lightroom (5+)

37 Test Prints