186 Appendix B
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list()
The list method is a static method that returns an array of profile names that match
specified class and colorspace criteria. This method may be used for example to return a
list of all Monitor profiles that have an RGB colorspace.
Specifying Profiles
The methods colorCorrect, colorFromImage, colorToImage, and
setSourceProfile all take a SourceProfile argument, a DestProfile argument, or both.
There are three methods for specifying these profiles:
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Specify the path to a profile on disk. By default this path is relative to the “color:” virtual
file system which includes both the Originals/Profiles directory in the Shared
files folder and the system color profile directory;
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Use an IccProfile object. These object may be constructed either from a path to a profile
on disk, or from an image with an embedded profile;
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Use the default profiles by specifying the string “rgb” for the default RGB colorspace
profile, or “cmyk” for the default CMYK colorspace profile. These default profiles are
defined in the global.properties file.
Accuracy and Reversibility of Color Conversions
The quality of the color reproduction of an image converted from one colorspace to another
depends on the following factors:
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The overlap between the gamut of the source device and the gamut of the destination
device;
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The quality of the color profile used (i.e., the number of samples used to generate the
conversion transform);
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The accuracy of the color profile;
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The rendering intent selected.
Devices with similar gamuts will produce the smallest color distortion. Typically,
converting from one monitor’s colorspace to another monitor’s colorspace results in no
noticeable loss of color quality. However, converting from an RGB colorspace to a CMYK
colorspace will typically result in changes in the color from the original. This loss is caused
by the fact that monitors typically have larger gamuts than printers. For photographic
images, this loss is typically small since most naturally occurring colors can be produced
equally well on monitors and printers. For computer-generated images, the loss is typically
larger since there are many colors representable on a monitor that cannot be achieved with
ink on paper.
Printer profiles are usually constructed with a large number of sample points for
converting colors to the printers’ colorspace. However, to make the profiles reasonably
small, far fewer sample points are usually provided for converting from the printers’
colorspace. Therefore, color conversions using printer profiles as the source colorspace
should be avoided whenever possible.
