SECTION 4.5
279
Color Spaces
>>
/MixingHints
<<
/Solidities
<< /Spot1 1.0
/Spot2 0.0
>>
/DotGain
<< /Spot1
function1
/Spot2
function2
/Magenta
function3
/Yellow
function4
>>
/PrintingOrder [/Magenta /Yellow /Spot1 /Spot2]
>>
>>
]
See Section 7.6.2, “Spot Colors and Transparency,” for further discussion of the
role of
DeviceN
color spaces in the transparent imaging model.
Multitone Examples
The following examples illustrate various interesting and useful special cases of
the use of
Indexed
and
DeviceN
color spaces in combination to produce multi-
tone colors.
Examples 4.17 and 4.18 illustrate the use of
DeviceN
to create duotone color spac-
es. In Example 4.17, an
Indexed
color space maps index values in the range 0 to
255 to a duotone
DeviceN
space in cyan and black. In effect, the index values are
treated as if they were tints of the duotone space, which are then mapped into
tints of the two underlying colorants. Only the beginning of the lookup table
string for the
Indexed
color space is shown; the full table would contain 256 two-
byte entries, each specifying a tint value for cyan and black, for a total of 512
bytes. If the alternate color space of the
DeviceN
space is selected, the tint trans-
formation function (object 15 in the example) maps the two tint components for
cyan and black to the four components for a
DeviceCMYK
color space by supply-
ing zero values for the other two components. Example 4.18 shows the definition
of another duotone color space, this time using black and gold colorants (where
gold is a spot colorant) and using a
CalRGB
space as the alternate color space. This
could be defined in the same way as in the preceding example, with a tint trans-