Dye Sublimation Color Management
Achieving Accurate Color Output Using Standardized Processes
Color Gamut
Definition of GAMUT
The gray area represents the entire
chromatic range. The colored
triangle represents the color display.
This is a typical CRT gamut reflected
by the sRGB ICC profile.
1.
The subset of colors which can be
accurately represented within a
given color space or by an certain
output device and ink combination.
2.
The complete set of colors found
within an image at a given time.
Converting a digitized image to a
different color space, or printing it to
a given medium generally alters its
gamut.
RGB and CMYK
RGB and CMYK are two different color spaces. The RGB color space uses light in colors of red,
green, and blue to create the visible spectrum. Our eyes see color in terms of reflected light, so the
observed world is closer to RGB than CMYK. That is why native RGB devices that use light to create
color, such as film recorders, scanners, and cameras can reproduce color fairly accurately.
RGB. Three colors of light, red, green and
blue make white light. Cyan, magenta and
yellow are also combinations of RGB.
The intensity of light also changes the color.
CMYK. Three inks, cyan, magenta and
yellow make black. In practice this black
lacks intensity, so a separate black (K) is
usually added. Red, green and blue are
made from CMYK.
Typical Color Spaces
Comparison of typical wide RGB
gamut for a color accurate
display, standard RGB gamut for
an ordinary color display and a
typical CMYK gamut for standard
pigment inks.
The Adobe RGB profile reflects
the wide RGB gamut, the sRGB
profile reflects a standard RGB
gamut.
Rendering Intent
Handling Out-of-Gamut Colors
Standard Rendering Intents
• Perceptual
• Relative Colorimetric
• Relative Colorimetric Black
Point Compensation
• Absolute Colorimetric
• Saturation
Rendering Intent
Perceptual
Graphic to be printed
Printer
•
•
•
•
Relationships among colors are preserved
Color space is uniformly shifted
Absolute colors are not preserved
Technically reversible depending on RIP
Rendering Intent
Absolute Colorimetric
Graphic to be printed
Printer
• In gamut colors are preserved
• Out of gamut colors are shifted
• Not reversible
Rendering Intent
Relative Colorimetric
Optional Black Point Compensation
•
•
•
•
•
•
Absolute Colorimetric with Compensation for White
Black Point Compensation also compensates for Black
In gamut colors are corrected for white and black points
Out of gamut colors are shifted
Black Point Compensation not supported on Adobe Output
Not reversible
Rendering Intent
Saturation
• Only CIELAB Lightness or L* is preserved
• All colors are shifted
• Not reversible
Simple Color Management
Chromatic and Ink Limitation Clipping Causes Unpredictable Results
ICC Color Management
Standards Based Approach to Achieving Predictable Color
Standard Adobe Design Environment
The standard Adobe design
environment is RGB using the
Adobe RGB color profile.
The target CMYK space is
typically US Web Coated
(SWOP) : an offset press.
Color Conversion Space
ICC Profiles Connect Design and Output Spaces
Using the L*a*b* Space as the Intermediary
RGB
CMYK
L*a*b*
Color Conversion Space
R
G
B
L
a
b
C
M
Y
K
34 74 141
17 16 -56
98 80 8
28 63 123
15 9
-46
97 79 14 58
4
12 3
-33
95 71 26 81
48 97
39
ICC Profiles are the basis for transforming color from the source space to the color conversion space
and then to the printer. They can be thought of as tables that define conversions to and from
L*a*b* space. Color values not in the table are interpolated.
Late Binding
RGB devices will have distinctly different white and black points than
CMYK output in relation to the colors that are produced.
RGB Display Device
CMYK on White Fabric
Conversion between RGB and CMYK accounts for differences in
gamut and white points. Optionally there can be compensation for
differences in the black point. Late binding allows these to be
mapped accurately to the final output device.
Output CMYK Color Mapping
Navy Blue
Pantone 282
Adobe RGB: 0 45 98
SWOP CMYK:
Dye Sublimation CMYK (Elvajet)
Differs with Rendering Intent
Absolute:
Perceptual:
Relative BPC:
Relative:
Saturation:
Proprietary RIP algorithms also
impact the color output.
100 68 0 54
96 82 14 71
96 73 11 61
94 65 10 71
95 80 17 75
97 78 09 61
ICC Color Management
Standards Based Approach to Achieving Predictable Color
Pantone Spots
Late binding: Design in RGB let RIP convert to CMYK
Modified late binding: Design in RGB and Named Colors
ICC Color Management
Standards Based Approach to Achieving Predictable Color
Single Environment
Two Profiles
1. Printer Profile RGB to CMYK
2. Named Color Profile
• RIP optionally bypasses printer profile and
uses the named color formula if it exists.
• Unnamed colors should be specified in RGB.
• Do not use raw CMYK specifications.
ICC Color Management
Linearization: Controls Perceived Optical Density
45% color value
1.25 optical density
1.25 optical density
?? pixel value
ICC Color Management
Ink Limits: Improve Optical Density and Control Chromatic Shifts
Gray
Cyan
Magenta
Black
Blue
Red