TIFF 6.0 Specification
Final—June 3, 1992
Section 16: CMYK Images
Motivation
This section describes how to store separated (usually CMYK) image data in a
TIFF file.
In a separated image, each pixel consists of N components. Each component
represents the amount of a particular ink that is to be used to represent the image at
that location, typically using a halftoning technique.
For example, in a CMYK image, each pixel consists of 4 components. Each com-
ponent represents the amount of cyan, magenta, yellow, or black process ink that
is to be used to represent the image at that location.
The fields described in this section can be used for more than simple 4-color pro-
cess (CMYK) printing. They can also be used for describing an image made up of
more than 4 inks, such an image made up of a cyan, magenta, yellow, red, green,
blue, and black inks. Such an image is sometimes called a high-fidelity image and
has the advantage of slightly extending the printed color gamut.
Since separated images are quite device-specific and are restricted to color pre-
press use, they should not be used for general image data interchange. Separated
images are to be used only for prepress applications in which the imagesetter,
paper, ink, and printing press characteristics are known by the creator of the sepa-
rated image.
Note: there is no single method of converting RGB data to CMYK data and back.
In a perfect world, something close to cyan = 255-red, magenta = 255-green, and
yellow = 255-blue should work; but characteristics of printing inks and printing
presses, economics, and the fact that the meaning of RGB itself depends on other
parameters combine to spoil this simplicity.
Requirements
In addition to satisfying the normal Baseline TIFF requirements, a separated TIFF
file must have the following characteristics:
• SamplesPerPixel = N.
SHORT. The number of inks. (For example, N=4 for
CMYK, because we have one component each for cyan, magenta, yellow, and
black.)
• BitsPerSample = 8,8,8,8 (for CMYK).
SHORT. For now, only 8-bit compo-
nents are recommended. The value “8” is repeated SamplesPerPixel times.
• PhotometricInterpretation = 5 (Separated - usually CMYK).
SHORT.
The components represent the desired percent dot coverage of each ink, where
the larger component values represent a higher percentage of ink dot coverage
and smaller values represent less coverage.
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