Understanding Color Management for Printers 12/15/11
Understanding Color Management for Printers
Understanding Color Management for Printers 12/15/11
Page 2.
Table of ContentsUnderstanding Color Management for Printers - - - - - - - - - - - - - - - - 1Table of Contents - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2Color Concepts - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3
RGB / CMYK - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4L*A*B* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5Gamut / Color Space / Color Model - - - - - - - - - - - - - - - - - - - - - - - - 6Rendering Intents - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
Ink Control - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 11Ink Restriction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 12Ink Linearization - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15Linearization - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17Ink Limit (Combined Ink Restriction) - - - - - - - - - - - - - - - - - - - - - - 18
Controlling Color - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 19ICC Profile - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20
Workflows - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23Workflow (Photo with a RIP) - - - - - - - - - - - - - - - - - - - - - - - - - - - 24Workflow (Photo with Epson Driver) - - - - - - - - - - - - - - - - - - - - - - 25Workflow (Proofing with a RIP) - - - - - - - - - - - - - - - - - - - - - - - - - 26Workflow (Production with a RIP) - - - - - - - - - - - - - - - - - - - - - - - - 27
Understanding Color Management for Printers 12/15/11
Page 3.
Color ConceptsTerms to Understand
Understanding Color Management for Printers 12/15/11
RGB / CMYK Page 4.
RGB / CMYK
C = CyanM = MagentaY = Yellow K = Black
R = RedG= GreenB = Blue
Cyan + Magenta + Yellow = BlackRed + Green + Blue = White
Magenta +Yellow = Red.
Red + Blue = Magenta.
Magenta + Cyan = Blue.
Yellow + Cyan = Green.Green + Blue = Cyan.
Red + Green =Yellow.
RGB coloring mixes light to make different colors.RGB is an additive system (adds light to make color)CMYK coloring mixes pigments to make different colors.Pigments absorb some frequencies (colors) of light, and reflect the desired frequency (color).CMYK is a subtractive system (absorbs undesired, and reflects desired light to make color).RGB and CMYK are opposites of each other.
Understanding Color Management for Printers 12/15/11
L*A*B* Page 5.
L*A*B*
L+
L-
A- A+
B-
B+
L* = Luminance (Brightness)A* = Green to RedB* = Blue to Yellow
L* range = 0 (Dark) to 100 (Light)A* range = - Green to + RedB* range = - Blue to + Yellow
L*A*B* values are device independent reference values.L*A*B* values can represent any color and brightness.L*A*B* values plot a color’s location in a 3 dimensional color space.
Understanding Color Management for Printers 12/15/11
Gamut / Color Space / Color Model Page 6.
Gamut / Color Space / Color Model
Color Model = RGB or CMYKColor Space = A theoretically defined range of colors within a color model (SRGB, Adobe RGB, etc.).Gamut = The actual range of colors that a device can reproduce.
Color Space Gamut
Color Model
Un 12/15/11
Re Page 7.
S
HPOInW
WU lors.U
DN
derstanding Color Management for Printers
ndering Intents
Rendering Intents
aturation
ow It Works:reserves the Saturation (color brightness) of colors. ut of Gamut Colors: will be moved to the closest fully saturated, in gamut color. Gamut Colors: may be moved to the closest, more saturated colors.hite Point: will not be changed.
hen To Use:se when the exact relationship between colors is not as important as rendering bright cose for charts and graphs.
ownside:o color accuracy.
Un 12/15/11
Re Page 8.
P
HCPO stination gamut. The other
he gamut, to maintain the
In visual relationship between
W
WUU
DLe mut colors, the contrast
derstanding Color Management for Printers
ndering Intents
erceptual
ow It Worksompresses all colors proportionately to bring out of gamut colors into gamut.reserves the visual relationship between colors.ut of Gamut Colors: the furthest out of gamut color will be moved to the edge of the de
out of gamut colors will be moved in the direction of the center of tvisual relationship between all colors.
Gamut Colors: will be moved in the direction of the center of the gamut to maintain the all colors.
hite Point: will not be changed.
hen To Use:se for photography.se when color accuracy is not as important as image detail.
ownside:ss Contrast: Because the gamut will be compressed proportionally to handle out of ga
between light and dark will also be reduced.
Un 12/15/11
Re Page 9.
R
HOInW
WUUU
DOIn
derstanding Color Management for Printers
ndering Intents
elative Colorimetric
ow:ut of Gamut Colors: will be moved to the closest in gamut color. Gamut Colors: will not be moved.hite Point: will not be changed.
hen:se for photography or productionse when detail in the shadow areas is importantse when visual accuracy is more important than measurable accuracy.
ownside:ut of Gamut colors may not be visibly accurate. Gamut colors may not measure accurately because the white point is not adjusted.
Un 12/15/11
Re Page 10.
A
HOInW
WUUU
DA e point is adjusted.
sted.
derstanding Color Management for Printers
ndering Intents
bsolute Colorimetric
ow:ut of Gamut Colors: will be moved to the closest in gamut color. Gamut Colors: will not be moved.hite Point: will be changed.
hen:se when measured color accuracy is more important than visual accuracy.se when spot color accuracy is important.se for proofing
ownside:lthough the colors may measure accurately, they may appear “shifted” because the whit
White Point adjusted to match destination. White Point not adju
Understanding Color Management for Printers 12/15/11
Page 11.
Ink ControlUnderstanding Media Saturation and Ink
Un 12/15/11
Ink Page 12.
P a and still increase gamut.In k.FaFa
1.
derstanding Color Management for Printers
Restriction
Ink Restrictionurpose: To determine the maximum amount of each ink that can be applied to the medi Other Words: For each ink, determine the maximum gamut with the least amount of inct: As saturation is approached, gamut increase rolls off.ct: Applying Ink with no gamut increase causes problems with no benefit.
Print Target Patches
Target PatchesCMYK 5% theoretical increase per patchFrom 5% to 100%
Un 12/15/11
Ink Page 13.
2.
75= 80 65
the maximum ach CMY ink
applied to the still increase
derstanding Color Management for Printers
Restriction
Measure and Graph each patch with the Eye One SpectroPhotometer.
C =M Y =
Determine amount of ethat can bemedia and gamut.
Un 12/15/11
Ink Page 14.
3.
derstanding Color Management for Printers
Restriction
Register maximum patch for each color.
C = 75M = 80Y = 65
Un 12/15/11
Ink Page 15.
FaFa ep. P he gradient steps.
S
(step 2)
ient patches
.
F n actual 5% gradient change.F n actual 5% gradient change.
derstanding Color Management for Printers
Linearization
Ink Linearizationct: The maximum amount of each ink that the media can accept is usually less than 100%. ct: The percentage of each ink that the media can accept is determined by the Ink Restriction st
urpose: The Ink Linearization step redefines the usable amount of ink to 100%, and evens out t
implified Explanation Using Cyan in as an example:1. Maximum usable Cyan ink = 75%
2. Redefine 75% as 100%
3. Print new target using redefined levels
4. Measure the 20 theoretical 5% gradient patches.
5. Compare the 20 theoretical 5% gradient patches with the 20 measured 5% grad
6. Adjust the measured 5% gradients until they match the theoretical 5% gradients
act: A 5% gradient change between 15% and 20% might require a 6% ink increase to produce aact: A 5% gradient change between 20% and 25% might require a 4% ink increase to produce a
Un 12/15/11
Ink Page 16.
In
ired) patch values
derstanding Color Management for Printers
Linearization
k Linearization
Measured patch values Theoretical (des
Un 12/15/11
Lin Page 17.
(correction values)
derstanding Color Management for Printers
earization
Linearization Measured patch values Linearization table
+
Target patch (desired) values
=
Understanding Color Management for Printers 12/15/11
Ink Limit (Combined Ink Restriction) Page 18.
Ink Limit (Combined Ink Restriction)Fact: Various combinations of inks react differently in terms of media saturation. Process: Various combinations of inks are printed at different saturation levels to determine the point that over satu-
ration occurs. Purpose: Combined ink “over saturation” points are used to further restrict ink levels applied to the media.
Ink Limit Explanation80 patches per row
1. Print swatch2. Inspect Swatch quickly and look for wet ink. Wet
ink = “over saturation”.
Ref # 0.05 Ref # 4.00
Understanding Color Management for Printers 12/15/11
Page 19.
Controlling ColorICC Profile
Un 12/15/11
IC Page 20.
B* to CMYK.
1.
ta.
derstanding Color Management for Printers
C Profile
ICC ProfileNote: A printer ICC Profile is used to accurately translate color data from L*A*
Print the Target
Note: A target consists of many color patches.Note: The more patches in a target, the more accurate the ICC Profile.Note: Each patch in a target represents a theoretical color.Note: All of the patches of theoretical colors are known as the Reference Da
3 pages of an ICC profile target.
Un 12/15/11
IC Page 21.
2.
otometer).h.easured Data.
s have been read.
derstanding Color Management for Printers
C Profile
Read (Measure) the Target.Note: Reading the target is performed by a color measuring device.Note: The color measuring device in this example is an Eye One (SpectroPhNote: The color measuring device reads the actual color value for each patcNote: All of the actual color values read by the Eye One are known as the M
Eye One SpectroPhotometer
Each line of patches is scanned by the Eye One, in sequence, until all patche
Un 12/15/11
IC Page 22.
3.
derstanding Color Management for Printers
C Profile
Create the ICC ProfileNote: In this example ProfileMaker 5.0 is being used to
create the ICC Profile.Note: ProflieMaker 5.0 compares the Reference Data with
the Measured Data.Note: The difference between the Reference Data and the
Measured Data is used to create the ICC Profile.Note: A Printer ICC Profile is a list color inaccuracies
inherent to the Printer.Note: A printer ICC Profile allows accurate translation from
L*A*B* to CMYK by providing the color inaccuracy information inherent to the Printer.
Note: A Printer ICC Profile is a table of color errors for a Printer.
Reference Data
Measured Data
Understanding Color Management for Printers 12/15/11
Page 23.
WorkflowsFor Production
For Proofing
For Photography
Understanding Color Management for Printers 12/15/11
Workflow (Photo with a RIP) Page 24.
Workflow (Photo with a RIP)Note: A Photo workflow is used to produce visually accurate color on a digital printer. Measurably
accurate color is not important Color Model: Source Image: RGB
L*A*B* to CMYK conversion:Output Profile: Accurately controls the conversion of L*A*B* to CMYK.Rendering Intent: Perceptual because it maintains the visual relationship between
all colors (including out of gamut) but may loose detail in shadow areas.
Relative Colorimetric because it maintains the visual relationship between all colors with no loss of details in shadow areas. Out of gamut colors may appear wrong.
RGB to L*A*B* conversion:Input Profile: Controls the conversion of RGB to L*A*B* with no restriction of color gamut.Rendering Intent: Perceptual because it maintains the visual relationship between all colors
(including out of gamut) but may loose detail in shadow areas.Relative Colorimetric because it maintains the visual relationship between all
colors with no loss of details in shadow areas. Out of gamut colors may appear wrong.
Epson InkJet:
Media Saturation Control:RIP: controls Ink Limit, Linearization, and Ink Restriction.
Understanding Color Management for Printers 12/15/11
Workflow (Photo with Epson Driver) Page 25.
Workflow (Photo with Epson Driver)Note: A Photo workflow is used to produce visually accurate color on a digital printer. Measurably
accurate color is not important Color Model: Source Image: RGB
L*A*B* to CMYK conversion:Output Profile: Attach to an application (PhotoShop) to accurately control the con-
version of L*A*B* to CMYK.Rendering Intent: Perceptual because it maintains the visual relationship between
all colors (including out of gamut) but may loose detail in shadow areas.
Relative Colorimetric because it maintains the visual relationship between all colors with no loss of details in shadow areas. Out of gamut colors may appear wrong.
RGB to L*A*B* conversion:Working Space: Use embedded or assign a working space.Rendering Intent: Perceptual because it maintains the visual relationship between all colors
(including out of gamut) but may loose detail in shadow areas.Relative Colorimetric because it maintains the visual relationship between all
colors with no loss of details in shadow areas. Out of gamut colors may appear wrong.
Epson InkJet:
Media Saturation Control:Epson Driver: controls Ink Limit, Linearization, and Ink Restriction.
Understanding Color Management for Printers 12/15/11
Workflow (Proofing with a RIP) Page 26.
Workflow (Proofing with a RIP)Note: A Proofing workflow is used to produce a sample of a “print job” before it is mass produced.
Because it is intended to be used for “customer sign off”, it must look exactly like the “print job” that the mass production press will produce. The proofing workflow restricts the gamut of a wide gamut printer (Epson Inkjet) to emulate the output of a narrower gamut printer (printing press). A proofing workflow must also be “color accurate” so that company specific colors (logos, etc.) are correct.
Color Model: Source Image: CMYK
L*A*B* to CMYK conversion:Output Profile: Accurately controls the conversion of L*A*B* to CMYK.Rendering Intent: Absolute Colorimetric with paper white compensation for visual
and measured accuracy of colors.
CMYK to L*A*B* conversion:Input Profile: Controls the conversion of CMYK to L*A*B* and restricts the Gamut to match a mass
production pressRendering Intent = Absolute Colorimetric (no paper white compensation because there is no paper
associated with this step).
Epson InkJet:
Media Saturation Control:RIP: controls Ink Limit, Linearization, and Ink Restriction.
Understanding Color Management for Printers 12/15/11
Workflow (Production with a RIP) Page 27.
Workflow (Production with a RIP)Note: A Production workflow is used to mass produce “output” on a digital press. The printing must
appear to be “color accurate” so that company specific colors (logos, etc.) look correct. Measurable color accuracy is important, but visual color accuracy is more important.
Color Model: Source Image: CMYK
L*A*B* to CMYK conversion:Output Profile: Accurately controls the conversion of L*A*B* to CMYK.Rendering Intent: Relative Colorimetric because it maintains the visual relationship
between white and all colors.
CMYK to L*A*B* conversion:Input Profile: Controls the conversion of CMYK to L*A*B* with no restriction of color gamut.Rendering Intent = Relative Colorimetric because it maintains the visual relationship between
white and all colors.
Epson InkJet:
Media Saturation Control:RIP: controls Ink Limit, Linearization, and Ink Restriction.