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DynaPDF Manual - Page 261

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Function Reference
Page 261 of 750
often called spot colorants, to produce effects that cannot be achieved with the standard process
colorants alone. Examples include metallic and fluorescent colors and special textures.
When printing a page, most devices produce a single composite page on which all process colorants
(and spot colorants, if any) are combined. However, some devices, such as imagesetters, produce a
separate, monochromatic rendition of the page, called a separation, for each colorant. When the
separations are later combined—on a printing press, for example—and the proper inks or other
colorants are applied to them, the result is a full-color page.
A Separation color space (PDF 1.2) provides a means for specifying the use of additional colorants or
for isolating the control of individual color components of a device color space for a subtractive
device. When such a space is the current color space, the current color is a single-component value,
called a tint, that controls the application of the given colorant or color components only.
The parameter Colorant specifies the colorant name which this Separation color space is intended to
represent. The special colorant name All refers collectively to all colorants available on an output
device, including those for the standard process colorants. When a Separation space with this
colorant name is the current color space, painting operators apply tint values to all available
colorants at once. This is useful for purposes such as painting registration targets in the same place
on every separation.
Such marks are typically painted as the last step in composing a page to ensure that they are not
overwritten by subsequent painting operations.
The special colorant name None never produces any visible output. Painting operations in a
Separation space with this colorant name have no effect on the current page.
The parameter Alternate specifies the alternate color space in which the color should be rendered if
the device does not support the specified colorant. The alternate color space can be any Device or
CIE based color space but not in turn a special color space like Separation, Indexed, or DeviceN.
The parameter Handle specifies the handle of the alternate color space if a CIE based color space
should be used. If the alternate color space is a device color space the parameter Handle is ignored.
The parameter Color specifies the alternate color value, defined in the alternate color space, which is
used if the device does not support the colorant.
A color value in a Separation color space consists of a single tint component in the range 0 to 255.
The value 0 represents the minimum amount of colorant that can be applied; 255 represent the
maximum. Tints are always treated as subtractive colors, even if the device produces output for the
designated component by an additive method. Thus, a tint value of 0 denotes the lightest color that
can be achieved with the given colorant, and 255 is the darkest. This convention is the same as for
DeviceCMYK color components but opposite to the one for DeviceGray and DeviceRGB.
Encoding of Colorant Names
Colorant names are interpreted in the code page 1252 (WinAnsi) by default. Because colorant names
are stored in UTF-8 Unicode format in PDF, it is also possible to pass UTF-8 encoded Unicode strings
 

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