1. COLOR MANAGEMENT FOR PHOTOGRAPHERS
A Tom Maddrey Images Workshop
Saturday, January 19, 13
2. AN INTRODUCTION
This seminar is about learning just enough color theory to have a superficial
understanding about WHY things work
We are not color scientists, nor should we strive to be, we simply need to
know how to get our photographs to look great
This class moreso than others will be filled with technical speak, I will try to
include all relevant definitions
Saturday, January 19, 13
3. WHAT IS A DIGITAL IMAGE?
Digital images are a series of 0’s and 1’s that are interpreted by the computer
into a full color image
The building blocks of digital images are pixels (picture elements) and each
pixel has a “Bit-Depth”
Bit-Depth - The number of bits available to each pixel
i.e. 1-bit = 2 options, 0 or 1 (0=black, 1=white)
2-bit = 4 options, 00 or 01 or 10 or 11 (black, dark gray, light gray, white)
Saturday, January 19, 13
4. WHAT IS A DIGITAL IMAGE
(CONT.)
8 Bits = 256 Shades (0-255 in Photoshop Speak)
16 Bits = 65, 536 Shades
A Color 8-Bit file is made up of three 8-bit channels giving a total bit depth of
24-bit color image (or 16.7 million colors possible)
Saturday, January 19, 13
5. WHAT IS COLOR?
Color is made up of different “Hues” which are pure, spectral colors
Color is interpreted by our brains, and is not a very complex system
For example, two colors of wildly different properties may appear “Red”
Additive Primaries - Red, Green, Blue
Subtractive Primaries - Cyan, Magenta Yellow
Saturday, January 19, 13
6. COLOR MODELS
A “Color Model” is a method of grouping numeric values by a set of
primaries
RGB, CMY, L*a*b*, CMYK
L*a*b* is a color model that represents all the colors humans can ever see
RGB needs a “Color Space” to determine the exact formulation
i.e. R255/G0/B0 is different in sRGB than Adobe RGB (1998)
Saturday, January 19, 13
7. COLOR SPACES
A Color Space is a scientifically defined portion of human vision
Work in conjunction with a Color Model
Often more restrictive than entire visible spectrum
Color Spaces can be Device dependent or Device independent
Device dependent includes: Epson Printers, Nikon Cameras
Device independent includes: L*a*b Color Space
Saturday, January 19, 13
8. LAB COLOR SPACE
Shaped like a sphere
L* axis goes from 0-100 and controls lightness
a* and b* axis controls the color chosen
Includes all colors of human perception
Is a Color Space and Color Model
Saturday, January 19, 13
9. MANAGEMENT VS. CORRECTION
Color Management seeks to achieve WYSIWYG by normalizing each part in
the color chain
Color Correction is altering a part of the color chain to your own preferences
or likings
A properly set up computer and monitor will render a poor image as a poor
image!
Saturday, January 19, 13
10. CALIBRATION VS. PROFILING
Calibration is designed to create and return a device to a known starting
point
i.e Monitors
Profiling is taking a snapshot of a device in a calibrated state to use as
reference
If the device deviates from a calibrated state the profile is no longer valid!
Saturday, January 19, 13
11. COLOR GAMUT
Color Gamut can best be thought of like crayons
A color gamut describes all possible colors
of a profile
Saturday, January 19, 13
12. COLOR TRANSLATION
When going from one color gamut to another (as in from file to print), we
need to “translate” the colors
We do this with “Gamut Mapping”
This translation (such as Adobe RGB to sRGB) is the source of many poor
prints and colors
Saturday, January 19, 13
13. RENDERING INTENTS
If a color is available in one color space and
not in another, the color is considered “Out-
of-Gamut”
Out of Gamut colors need to be compressed
or clipped to fit in the destination color space
Clipping - Moving OOG colors to
“Nearest Neighbor” color in Gamut
Compression - Compresses OOG colors to
maintain relationships between colors, but
affect other colors as well
Saturday, January 19, 13
14. RENDERING INTENTS (CONT.)
Perceptual - Transforms OOG colors to the new space so the image is
“perceived” in the same way
Good for lots of OOG colors
Relative Colormetric - Uses Gamut Clipping to adjust only those OOG colors
and moves them to the nearest color match in the destination, does not affect
other colors
Good when not many OOG colors
Saturday, January 19, 13
15. ICC PROFILES
Input Profiles, Display Profiles, and Output Profiles
Input Profiles - Describe how a camera or scanner “Sees” color
Display Profiles - Describe how a monitor “Reproduces” color
Output Profiles - Describes how a printer “Renders” color
Profiles can be “Assigned” or embedded in an image
Saturday, January 19, 13
17. PHOTOSHOP AND COLOR
MANAGEMENT
Photoshop 5.0 was the first version to have built in color management
with .icc profiles
Photoshop has “Working Spaces” that is the color management you are
working in, separate from your display
You always want your working space to have more information than the
most restrictive process (i.e. printing)
Saturday, January 19, 13
18. WORKING SPACES
sRGB - Useful if your output is only low res, such as web or tv
Adobe RGB (1998) - Useful all around working space, including PrePress
(CMYK), most useful for 8-bit work
ProPhoto RGB - VERY large working space, includes all color, even some
outside CIE LAB, best for 16-bit work
Saturday, January 19, 13
19. PHOTOSHOP COLOR SETTINGS
To access, Command/Control - Shift - K
Broken Down into:
Settings, Working Spaces, Color Management Policies, Conversion
Options, and Advanced Controls
We will look in depth at these setting in the next Photoshop demo
Saturday, January 19, 13
20. ASSIGN AND CONVERT TO
PROFILE
Assign Profile tells PS what profile is associated with the numbers in the
image
Useful when a document does not have an embedded profile
Convert to Profile is where you convert between color spaces
Useful when you are moving the image to another place (i.e. an offsite
printer
Saturday, January 19, 13
21. SOFT PROOFING LIKE A PRO
Soft Proofing is a way to preview what the final output (usually from a
printer) will look like before you print!
Soft proofing most closely approximates the final print on your screen
Takes a while to get used to, but is the single most important thing you can
do to get good images the first time
Set up the proof
Adjust contrast, saturation, curves
Compare with original
Saturday, January 19, 13
22. A QUICK PRINTING PRIMER
After you soft proof your image, the next step is to take it to print
When printing, you need to make sure you are applying color management
at least once, and not twice!
Print with Preview in PS
PhotoShop Manages Color
Document is selected
Every Printer Driver is Different, but all need NO COLOR
MANAGEMENT
Saturday, January 19, 13
24. CALIBRATING A MONITOR
When Calibrating a monitor, here are a quick list of settings:
White Point: D65 or 6500K
Gamma 2.2
Update display profiles at least every month
Every two weeks would be preferred
Inexpensive choices: ColorMunki, Eye One Display LT
Saturday, January 19, 13
25. PROFILING A PRINTER
Printer profiles are custom to that particular printer, ink set, and paper
There are good starting points with generic profiles, but a custom profile is
light years beyond these generics
Newer printers are beginning to include a spectrophotometer in the printer
itself
Saturday, January 19, 13
26. PROFILING A PRINTER (CONT.)
The first step is to print a target with no color management whatsoever
This means off in Photoshop Dialog and off in Printer Dialog
Next you use a photospectrometer to measure the targets against a known
set of reference points
The program adjusts for the differences
Saturday, January 19, 13
