Post on 07-Mar-2016
description
“It looked fine on my screen !”
“It printed perfectly on my ink-jet printer !”
“ But my client liked the colour on the laser-proof I sent her !”
“ The blue background on page 3 is a different colour blue from the same background on page 19 !”
Colour Management for PrintThe printer-designer relationship
“It printed perfectly on my ink-jet printer !”
Many factors govern the appearance of any given printed colour including the type of printing device, print substrate, print-medium or quality of print-medium manufacture. A printing device, such as a desk-top printer or printing press, interprets any given colour uniquely to itself – an interpretation described as being native to that particular device.
Colour Management for PrintThe printer-designer relationship
“ But my client liked the colour on the laser-proof I sent her !”
A consistent appearance to any given colour is not possible because of differences in printing environments, printing devices, ink/ toner manufacture, ink/ toner composition and print substrates. For example, 100% magenta will, consequently, appear different, in comparison, when printed on: sheet-fed offset coated; sheet-fed offset uncoated; web-offset newsprint; web-offset uncoated; web-offset coated; desk-top inkjet and desk-top laser.
Colour Management for PrintThe printer-designer relationship
Colour Management for PrintThe printer-designer relationship
R255 B255 M100 M100 M100
Adobe (1998) Coated Uncoated Canon SP1
Colour Management for PrintThe printer-designer relationship
“ The blue background on page 3 is a different colour blue
from the same background on page 19 !”
The print environment, such as humidity or time of day, can affect the printed appearance of any given colour. Viewing a printing press in action is a basic essential for the designer. For example, to observe the amount of adjustment required to ink-flow during a press run on any given day is enlightening, to say the least…
Colour Management for PrintThe printer-designer relationship
International�Color�Consortium�(��ICC��)
Founded in 1993 by
Apple Computer Inc., Adobe Systems Incorporated, Agfa-Gevaert N.V., Eastman Kodak Company, FOGRA-Institute ( honorary ), Microsoft Corporation, Silicon Graphics Inc., Sun Microsystems, Inc. and Taligent Inc.
Now comprises more than seventy members.
Colour Management for PrintLaying a foundation
Colour Management for PrintColour management
Colour Management for PrintLaying a foundation
The�gamut�of�human�vision
The CIE XYZ 1931 colour space, which shows the average extent of perceived colour, in a 2° field of view, on the fovea of a human eye with normal colour vision – known as the Standard Observer
The�gamut�of�human�vision
CIE L*, a*, b* 1976 adjustment to the CIE XYZ 1931 colour space, which demonstrates perceived changes between colours and levels of lightness more accurately
Colour Management for PrintLaying a foundation
6504K D65 ° 5003K D50 °
Colour Management for PrintLaying a foundation
+ b*
+ L*
– L*
– a* + a*
– b*
CIE�L*,a*,b*
The standard colour space for device-independent colour management
L*= Light compared to dark
a*= red compared to green
b*= yellow compared to blue
Colour Management for PrintLaying a foundation
Adobe�RGB�(1998)�gamut
Developed using RGB values available on a computer monitor to which most CMY values can be mapped
Colour Management for PrintLaying a foundation
Generic��CMY�gamut
The extent of this gamut varies according to the native gamut of a respective CMYK output device
Colour Management for PrintLaying a foundation
Adobe�RGB�(1998)�/�generic��CMY�gamut
This relationship forms the basis of typical gamut-mapping transforms in a device-independent colour-managed workflow
Colour Management for PrintLaying a foundation
RGB
RGB is an additive model, where adding one colour to another increases its brightness
R+G+B = light.
Colour Management for PrintLaying a foundation
CMY
CMY is a subtractive model, where adding one colour to another decreases its brightness
C+M+Y = dark
K is added in the print process because CMY inks are not sufficiently pure
Parameters for setting-up a colour-management policy are dependent upon the type of source document and its intended output. The user must have a clear understanding of which type of colour-managed workflow is pertinent to any given job.
RGB > RGB
RGB > CMYK
CMYK > CMYK
Colour Management for PrintColour management
Colour Management for PrintColour management
Working-space policies
PRESERVE EMBEDDED PROFILES
Upon opening or importing images, existing embedded source profiles are maintained irrespective of the active working-space profile. When creating new documents the active working-space profile is assigned – however, RGB and Greyscale images may be rendered perceptually, CMYK images are rendered absolutely, according to original colour numbers and no mapping occurs.
This policy is useful where an opened or imported source has no specific device association and is merely being passed-through Photoshop.
Colour Management for PrintColour management
Working-space policies
CONVERT TO WORKING SPACE
Upon opening or importing images, existing embedded source profiles are discarded and mapped into the active working space profile. When creating new documents the active working-space profile is assigned. RGB, CMYK and Greyscale images are rendered perceptually, according to relative colour and tonality, resulting in shifts from their original colour numbers.
This policy is useful for device-dependent output.
Colour Management for PrintColour management
Colour Management for PrintLaying a foundation
Absolute�colorimetric
Source gamut mapped to nearest equivalent.
All in-gamut colours retained.
White point retained
Colour Management for PrintLaying a foundation
Relative�colorimetric
Source gamut mapped to nearest equivalent to preserve hue and lightness.
All in-gamut colours retained.
White and black points adjusted
Colour Management for PrintLaying a foundation
Perceptual
Source gamut compressed entirely.
Perceived colour and tonal relationships preserved.
Most in-gamut colours adjusted
Colour Management for PrintLaying a foundation
Saturation
Source gamut mapped to most intense saturation possible.
All in-gamut colours adjusted to most intense relative saturation.
Total – ink limit ( TIL ) – ink coverage ( TIC ) – area coverage ( TAC )
Newsprint web-offset : TAC 240% – 280%
General web-offset : TAC 280% – 310%
Uncoated sheet-fed offset : TAC 280% – 300%
General coated sheet-fed offset : TAC 300% – 330%
Specialist coated sheet-fed offset : TAC 320% – 340%
Colour Management for PrintWorking method
How black is black ? | R=0 G=0 B=0
Coated FOGRA39 : C 91 M 79 Y 62 K 97 ; Total ink = 329 %
Uncoated FOGRA29 : C 96 M 70 Y 46 K 86 ; Total ink = 298 %
Web-coated : C 75 M 68 Y 67 K 90 ; Total ink = 300 %
Web-uncoated : C 63 M 52 Y 50 K 95 ; Total ink = 260 %
Canon i9950 SP1 : C 93 M 81 Y 57 K 93 ; Total ink = 324 %
Canon i9950 MP1 : C 89 M 79 Y 61 K 97 ; Total ink = 326 %
Colour Management for PrintWorking method
Colour Management for PrintWorking method
How white is white ?
There are, typically, two kinds of white, or highlight, in a picture:
Specular – derived from high concentrations of light, e.g. pinpoint light sources and high-key reflection points
White surface – where some tonality and / or texture is expected
How white is white ?
OFFSET-LITHOGRAPHY : WHITE SURFACE
Coated FOGRA39 : R 241 G 241 B 241 / C 6 M 5 Y 5 K 0
Uncoated FOGRA29 : R 237 G 237 B 237 / C 7 M 5 Y 5 K 0
DESK-TOP BUBBLE-JET : WHITE SURFACE
Canon i9950 SP1 : R 240 G 240 B 240 / C 4 M 5 Y 4 K 0
Canon i9950 MP1 : R 235 G 235 B 235 / C 4 M 4 Y 4 K 0
Colour Management for PrintWorking method