KcsLoadHints

typedef unsigned long KcsLoadHints;

KcsLoadHints is a data type of one argument in the following functions:

• KcsConnectProfiles()

• KcsCreateProfile()

• KcsOptimizeProfile()

• KcsLoadProfile()

• KcsModifyLoadHints()

KcsLoadHints gives the KCMS framework a hint as to how a profile's allocated resources should be managed. It lets the caller supply information to the KCMS framework about what, how, when, and where to load and unload the profile. It consists of a set of bit definitions that allow the application to supply more than one option. KcsLoadHints also lets the application mix the operation hints and content hints for greater flexibility.

Table 3-2 shows the bits positions (31-0) of an unsigned long representing KcsLoadHints and KcsOperationType. See Table 3-3 for more information on the bit mask values.

Table 3-3 lists the values for the load hint bit masks.

KcsMaskOp

#define KcsOpForward (0x00000001)
#define KcsOpReverse (0x00000002)
#define KcsOpSimulate (0x00000004)
#define KcsOpGamutTest (0x00000008)
#define KcsOpAll (0x000003FF)

KcsMaskEffect

#define KcsEffect (0x00000200)

KcsMaskLoadWhere

#define KcsHeapApp (0)
#define KcsHeapSys (0x00000400)

KcsMaskAttr

#define KcsAttributes (0x00000800)

KcsMaskUnloadWhen

#define KcsUnloadNow (0x00001000)
#define KcsUnloadWhenFreed (0x00002000)
#define KcsUnloadWhenNeeded (0x00004000)
#define KcsUnloadAfterUse (0x00008000)

KcsMaskCont

#define KcsContUnknown (0x00000000)
#define KcsContGraphics (0x00010000)
#define KcsContImage (0x00020000)
#define KcsContColorimetric (0x00040000)
#define KcsContAll (0x00FF0000)

KcsMaskLoadWhen

#define KcsLoadNever (0x00000000)
#define KcsLoadNow (0x01000000)
#define KcsLoadWhenNeeded (0x02000000)

#define KcsLoadWhenIdle (0x04000000)

KcsMaskLogical

#define KcsStartOverWithThis (0x10000000)
#define KcsAddToCurrentHints (0x00000000)

Example 3-3 shows some combinations of the masks.

Example 3-3 Load Hint Bit Mask Combinations

#define KcsLoadAllNow
 (KcsAll|KcsLoadNow|KcsUnloadWhenFreed|KcsStartOverWithThis)
 #define KcsLoadAllWhenNeeded
 (KcsAll|KcsLoadWhenNeeded|KcsUnloadWhenFreed|KcsStartOverWithThis)
 #define KcsLoadAttributesNow
 (KcsAttributes|KcsLoadNow|KcsUnloadWhenFreed|KcsStartOverWithThis)
 #define KcsLoadMinimalMemory
 (KcsAll|KcsLoadWhenNeeded|KcsUnloadAfterUse|KcsStartOverWithThis)
 #define KcsPurgeMemoryNow
 (KcsAll|KcsLoadWhenNeeded|KcsUnloadNow|KcsStartOverWithThis)

Typically you might use two of these bit mask combinations: KcsLoadAttributesNow and KcsLoadAllNow. KcsLoadAttributesNow loads the profile attributes only. KcsLoadAllNow loads the entire profile (header, attributes, and operations that can be performed on CCPs to transform color data).

Operation Hint Constants

Four operation hint constants describe the operations in Table 3-2 that can be performed on CCPs to transform color data (are also referred to as transforms). These are

• forward

• reverse

• simulate

• gamut-test

Operations Performed

Ordinarily, an application transforms data in the forward direction, for example, from a scanner to a printer. Your application can specify KcsOpForward to achieve this.

Your application also may be able to convert the data in the reverse direction, for example, from a monitor to a scanner. To do this, it specifies KcsOpReverse. The reverse direction can be useful if, for instance, you are given colors in the monitor device color space and you want to transform the data back to the original scanner color space.

KcsOpSimulate lets your application simulate the effect of running data through a complete profile, but leaves it in the color space of the last device profile in the connected sequence of profiles. For instance, suppose you have a CCP consisting of scanner => printer => monitor profiles. Your application can use the CCP with the simulate operation on monitor data to produce monitor data that simulates the result of printing the data. For this to work, it must have connected a destination device to a source => destination combination. In this situation, the scanner is the source device, the printer is the first destination device, and the monitor is the connected destination device.

A typical color monitor can display colors that a printer cannot print. Similarly, many printers are capable of printing colors that cannot be displayed on a color monitor. KcsOpSimulate lets users preview what a graphic or image will look like (approximately) when printed.

KcsOpGamutTest lets your application determine if each source color is in the gamut of the destination device. The resulting image contains 0 for a pixel with in-gamut color and FF for a pixel with out-of-gamut color.

Constraints When Using Operation Hints

Because of constraints in the CMM or in the specific profile, not all of the above operations may be supported. Also, some CMMs may offer additional custom operations. Your application can use KcsGetAttribute() and supply the KcsAttrSupportedOperations attribute to determine which operations are supported by a given profile.

Specifying any single or combination of operation load hints to the KcsLoadProfile() function has no effect. KCMS equates this to KcsOpAll. When the application calls KcsConnectProfiles(), KCMS automatically loads all the transforms to support the full range of operations.

Your application cannot specify KcsOpAll as an argument to KcsEvaluate().

Content Hint Constants

The content hint constants let your application specify hints about what kind of data is being processed. A CMM can use these hints to better convert the data as your application requests. For instance, these hints may be used to adjust the gamut-mapping technique (the approach used to map the colors falling outside a device's capability to colors that the device can produce).

The "C" API defines the following constants:

• KcsContImage describes photographic data, photorealistic data, or some 3-D rendering schemes. In this kind of data, fine gradations of luminance and relative color differences are important.

• KcsContGraphics describes computer-generated color data, which is likely to have large flat regions of highly saturated colors. In graphics data, an attempt is made to maintain the brightness and distinctness of the colors.

• KcsContColorimetric describes colors in terms of CIE specifications intended to be reproduced without modification. This is important when specific spot colors have been selected.

• KcsContUnknown describes color data content that is not known by the application. The CMM provides a general default for this case.

ICC content hints are called rendering hints. Currently, the following rendering hints defined are:

icPerceptual = KcsContImage  
icRelativeColorimetric = KcsContColormetric  
icSaturation = KcsContGraphics  
icAbsoluteColorimetric = <no equivalent>

If your application has input color data that matches more than one of these content hints (for example, a complicated page layout), it can specify KcsContUnknown to produce adequate results. For best results, your application may have to divide color data into different parts (for example, separate graphics and images parts). After dividing, your application can process each part separately, applying the appropriate content hint to each part.

If your application specifies KcsContAll as an argument to KcsConnectProfiles(), the resultant profile has the full range of content hints available to it. If it does not, the resultant profile is restricted to the content hints supplied by the function.

CMMs can define additional custom content hints, for example:

• To indicate what kind of output is being produced, such as a photograph or a computer-generated graphic.

• To indicate that speed is more important than color image quality; therefore, compromised color is acceptable.