Monkeybread Software - DynaPDF Manual

DynaPDF Manual - Page 256

Function Reference

Page 256 of 839

Note: A DeviceN color space whose component colorant names are all None always discards its

output, just the same as a Separation color space for None; it never reverts to the alternate color

space. Reversion occurs only if at least one color component (other than None) is specified and is not

available on the device.

Encoding of Colorant Names

Colorant names are interpreted in the code page 1252 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 to the

function. However, the function must be able to distinguish between both string formats. To achieve

this, the parameter NumColorants accepts the special flag 0x10000000 that specifies that the Colorants

array contains UTF-8 encoded strings. The flag must be combined with the number of colorants

with a binary or operator:

numColorants |= 0x10000000;

// C/C++, C#

numColorants

= numColorants Or &H10000000 // Visual Basic

numColorants := numColorants or $10000000

// Delphi

DeviceN Attributes

DeviceN and NChannel color spaces can contain optional attributes describing further

characteristics of the color space. The most important attributes are the definitions of the spot and

process colorants which are used by the color space. These attributes are required to enable certain

features in a viewer application, e.g. the Output Preview in Adobe's Acrobat depends on it.

Notice: Although the definition of spot and process colorants is optional, it is bad practice to create a

DeviceN color space without this information.

Spot colorant attributes

Spot colorants can be defined as normal Separation color spaces and then added as an attribute to

the color space with AddDeviceNSeparations(). The advantage is that the alternate color space and

tint transformation function of the Separation color space describe the appearance of that colorant

alone, whereas those of a DeviceN color space describe only the appearance of its colorants in

combination. The definition of the spot colorants is optional but strongly recommended because it is

the only way to render a spot colorant alone. Note that the Output Preview in Adobe's Acrobat

depends on properly defined spot colorants.

Process colorant attributes

If a DeviceN color space contains components of a process color space then it should include

information about the color space in which these components are defined. This can be done with the

function AddDeviceNProcessColorants() which accepts an array of colorant names and the

underlying process color space. The process color space can be any device or CIE based color space.

If an ICCBased color space is specified, it must provide calibration information appropriate for the

process color components specified in the names array of the DeviceN color space.