KCMS Profile Attributes and ICC Tags

5

Every profile contains a group of attributes (or tags) that describes the characteristics of the profile. Attributes and tags are specified by name, value, and status (whether they are required or optional). Attributes and tags are identical; the term attributes existed before the ICC tags came into use. Attributes are KCMS-framework specific. Tags are primarily defined in the ICC specification (and the icc.h header file), except for a few that are KCMS-framework specific. These tags are defined in the kcstypes.h header file and are registered with the ICC. Tags are discussed in this chapter.

Several API functions create and modify tags, while others define what is stored in a tag; see Chapter 4, "Functions" for detailed descriptions of all functions.

Attribute Value

An attribute's value is defined in the val field of the KcsAttributeValue data structure (see page 27). Since there are many possible data types for val, you need some way of interpreting the value as the correct data type. The KcsAttributeType data type provides this interface (see page 26).

Required and Optional Attributes

Attributes are either required or optional for all profiles. The software that creates the profile must assign required attributes.

KCMS Framework Tags

The following tags are KCMS-framework specific. They are not defined in the ICC specification (or icc.h); they are defined in the kcstypes.h header file. These tags are never stored in a profile. They are used to access portions of an ICC profile that are not covered by tags.

`icSigHeaderTag`

#define icSigHeaderTag (0x69636864UL) /* 'ichd' */

This data structure is an ICC header. The header file contains useful attribute information.

`icSigNumTag`

#define icSigNumTag (0x6E746167UL) /* 'ntag' */

This data structure returns a KcsULong value that is the number of ICC profile attributes and tags in a file. This is a read-only attribute; it cannot be set. The count includes the icSigHeaderTag, icSigNumTag and icSigListTag entries.

`icSigListTag`

#define icSigListTag (0x6C746167UL) /* 'ltag' */

This data structure is a list of the ICC attributes and tags in a profile.

Example

The following code sample shows you how to use the icSigNumTag and icSigListTag data structures.

Code Example 5-1 icSigNumTag and icSigListTag


  #include <kcms/kcs.h>  
  KcsAttributeValue attrValue, *attrPtr;  
  int                   i;  
  char                  *tmp;  
  
  /* Set the value of countSupplied */  
  attrValue.base.countSupplied = 1;  
  attrValue.base.type = KcsULong;  
  
  /* Get the number of attributes in the profile */  
  status = KcsGetAttribute(profile, icSigNumTag, &attrValue);  
  if (status != KCS_SUCCESS) {  
       KcsFreeProfile(profile);  
       exit(1);  
  }  
  
  /* Make space to get a list of all tags */  
  size = sizeof(KcsAttributeBase) + sizeof(long)*attrValue.val.uLongVal[0];  
  if ((attrPtr = (KcsAttributeValue *)malloc(size)) == NULL) {  
       perror("malloc failed : ");  
       KcsFreeProfile(profile);  
       exit(1);  
  }  
  
  /* Get the list of tags */  
  attrPtr->base.type = KcsULong;  
  attrPtr->base.sizeOfType = sizeof(long);  
  attrPtr->base.countSupplied = attrValue.val.uLongVal[0];  
  status = KcsGetAttribute(profile, icSigListTag, attrPtr);  
  if (status != KCS_SUCCESS) {  
       KcsFreeProfile(profile);  
       free (attrPtr);  
       exit(1);  
  }  
  
  /* Print the list */  
  printf("Number of tags = %d\n", attrPtr->base.countSupplied);  
  for (i=0; i<attrPtr->base.countSupplied; i++) {  
       tmp = (char *)&attrPtr->val.uLongVal[i];

Code Example 5-1 icSigNumTag and icSigListTag (Continued)


       printf("Tag # = %d, Tag Hex = 0x%x, Tag Ascii = %c%c%c%c\n", i,  
           attrPtr->val.uLongVal[i]; *tmp, *(tmp+1), *(tmp+2), *(tmp+3));  
  }  
  
  KcsFreeProfile(profile);  
  free (attrPtr);

Required ICC Tags

Some tags in the profile structure are required by the default CMM. These tags provide the necessary data for the CMM to translate the color information.

The following ic* tag names are defined in the icc.h header file. The ic* data structures are defined starting on page 107 and are in the icc.h header file. See the ICC specification for more detailed definitions of device profiles, tag names and tag types (or data structures). ICC specification section titles are referenced in each profile class section below. (By default, the ICC specification is located online in the SUNWsdk/kcms/doc directory.)

Note - Lut8 and Lut16 tables are considered transforms by the KCMS framework and are not available as attributes.

The following tags are are required depending on the profile type and interpretation. The first five tags listed cannot be set using KcsGetAttribute() and KcsSetAttribute(). Instead they must be set with KcsUpdateProfile(). The grayTRCTags fully support reading and writing. They are required for input profiles only.

Tags Required Depending on Interpretation

Profile	Tag Name	Interpretation
Input Profile	AToB0Tag	None
Display Profile	AToB0Tag	None
Output Profile	BToA0Tag	Perceptual rendering
Output Profile	BToA1Tag	Colorimetric rendering
Output Profile	BToA2Tag	Saturation rendering

Tags Required Depending on Interpretation

Profile	Tag Name	Interpretation
Input Profile	grayTRCTag	Depends on intent
Display Profile	grayTRCTag	Additive
Output Profile	grayTRCTag	Subtractive

Input Profile

The following tags are for input devices such as scanners. See "Input File" in the ICC specification for more information.

Monochrome Input Profiles

Tag Name............Tag Type

icSigHeaderTag                      icHeader
icSigProfileDescriptionTag          icTextDescription
icSigGrayTRCTag                     icCurve
icSigMediaWhitePointTag             icXYZArray
icSigCopyrightTag                   icText

RGB Input Profiles

Tag Name............Tag Type

icSigHeaderTag                      icHeader
icSigProfileDescriptionTag          icTextDescription
icSigRedColorantTag                 icXYZArray
icSigGreeColorantTag                icXYZArray
icSigBlueColorantTag                icXYZArray
icSigRedTRCTag                      icCurve
icSigGreenTRCTag                    icCurve
icSigBlueTRCTag                     icCurve
icSigMediaWhitePointTag             icXYZArray
icSigCopyrightTag                   icText

CMYK Input Profiles