Issuu on Google+

Colour Management for Print The printer-designer relationship

“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 Print The 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 Print The 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; sheetfed offset uncoated; web-offset newsprint; web-offset uncoated; web-offset coated; desk-top inkjet and desk-top laser.


Colour Management for Print The printer-designer relationship

R255 B255

M100

M100

M100

Adobe (1998)

Coated

Uncoated

Canon SP1


Colour Management for Print The printer-designer relationship


Colour Management for Print The 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 Print Laying a foundation

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 Print Colour management


Colour Management for Print Laying 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


Colour Management for Print Laying a foundation

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

5003K D50  6504K D65 ° °


Colour Management for Print Laying a foundation

CIE L*,a*,b*

+ L*

The standard colour space for deviceindependent colour management L*= Light compared to dark a*= red compared to green b*= yellow compared to blue

+ b* – a*

+ a* – b*

– L*


Colour Management for Print Laying 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 Print Laying 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 Print Laying a foundation

Adobe RGB (1998) / generic  CMY gamut This relationship forms the basis of typical gamutmapping transforms in a deviceindependent colourmanaged workflow


Colour Management for Print Laying a foundation

RGB RGB is an additive model, where adding one colour to another increases its brightness R+G+B = light.


Colour Management for Print Laying 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


Colour Management for Print Colour management

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 Print Colour management


Colour Management for Print Colour 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 Print Colour 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 Print Laying a foundation

Absolute colorimetric Source gamut mapped to nearest equivalent. All in-gamut colours retained. White point retained


Colour Management for Print Laying 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 Print Laying a foundation

Perceptual Source gamut compressed entirely. Perceived colour and tonal relationships preserved. Most in-gamut colours adjusted


Colour Management for Print Laying a foundation

Saturation Source gamut mapped to most intense saturation possible. All in-gamut colours adjusted to most intense relative saturation.


Colour Management for Print Working method

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 Print Working 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 Print Working 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


Colour Management for Print Working method

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


BAGC3-PP CMfP 2010