Xojo Developer Conference
25/27th April 2018 in Denver.
MBS Xojo Conference
6/7th September 2018 in Munich, Germany.

DynaPDF Manual - Page 68

Previous Page 67   Index   Next Page 69

Color spaces
Page 68 of 750
If the colorant name associated with a Separation color space does not correspond to a colorant
available on the device, the application arranges for subsequent painting operations to be performed
in an alternate color space. The intended colors can be approximated by colors in a device or CIE-
based color space, which are then rendered with the usual primary or process colorants.
The alternate color space is a required parameter of the function CreateSeparationCS(). Therefore, if
a CIE based color space should be used as alternate color space then this color space must be created
before the Separation color space.
Once the color space was created it can be set with SetExtColorSpace().
A Separation color space can be applied to vector graphics and images with a color depth of 1, 2, 4,
or 8 bits. See also Color Spaces and Images.
DeviceN Color Space
DeviceN color spaces (PDF 1.3) can contain up to 32 color components. They provide greater
flexibility than is possible with standard device color spaces such as DeviceCMYK or with individual
Separation color spaces. For example, it is possible to create a DeviceN color space consisting of only
the cyan, magenta, and yellow color components, with the black component excluded.
DeviceN color spaces are used in applications such as these:
High-fidelity color is the use of more than the standard CMYK process colorants to produce
an extended gamut, or range of colors. A popular example is the PANTONE Hexachrome
system, which uses six colorants: the usual cyan, magenta, yellow, and black, plus orange and
green.
Multitone color systems use a single-component image to specify multiple color components.
In a duotone, for example, a single-component image can be used to specify both the black
component and a spot color component. The tone reproduction is generally different for the
different components. For example, the black component might be painted with the exact
sample data from the single-component image; the spot color component might be generated
as a nonlinear function of the image data in a manner that emphasizes the shadows.
DeviceN was designed to represent color spaces containing multiple components that correspond to
colorants of some target device. As with Separation color spaces, PDF consumer applications must
be able to approximate the colorants if they are not available on the current output device, such as a
display. To accomplish this, the color space definition provides a tint transformation function that
can be used to convert all the components to an alternate color space.
While the transformation function is automatically created for a Separation color space this is not
possible for DeviceN color spaces. The transformation function consists always of a Postscript
Calculator Function and it is a required parameter of the function CreateDeviceNColorSpace().
Note that the alternate color space is a required parameter too. Therefore, if a CIE based color space
should be used as an alternate color space then this color space must be created before the DeviceN
color space can be created.
 

Previous topic: Separation Color Space

Next topic: Handling of non-device color spaces