home *** CD-ROM | disk | FTP | other *** search
- Embedding ICC Profiles in TIFF
-
- The discussion below assumes some familiarity with TIFF internal structure.
- It is beyond the scope of this document to detail the TIFF format, and readers are
- referred to the "TIFF(tm) Revision 6.0" specification, which is available from
- the Aldus Corporation.
-
- The InterColor Consortium (IC) has been assigned a private TIFF tag for
- purposes of embedding IC device profiles within TIFF image files. This is not a
- required TIFF tag, and Baseline TIFF readers are not currently required to read
- it. It is, however, strongly recommended that this tag be honored.
-
- A IC device profile is embedded, in its entirety, as a single TIFF field or
- Image File Directory (IFD) entry in the IFD containing the corresponding image
- data. An IFD should contain no more than one embedded profile. A TIFF file may
- contain more than one image, and so, more than one IFD. Each IFD may have its
- own embedded profile. Note, however, that Baseline TIFF readers are not
- required to read any IFDs beyond the first one.
-
- The structure of the IC Profile IFD entry is as follows:
-
- Bytes 0-1 The TIFF Tag that identifies the field = 34675(8773.H)
- Bytes 2-3 The field Type = 7 = UNDEFINED (treated as 8-bit bytes).
- Bytes 4-7 The Count of values = the size of the embedded IC profile in bytes.
- Bytes 8-11 The Value Offset = the file offset, in bytes, to the beginning of
- the IC profile.
-
- Like all IFD entry values, the embedded profile must begin on a word boundary,
- so the Value Offset will always be an even number.
-
- A TIFF reader should have no knowledge of the internal structure of an embedded
- IC profile and should extract the profile intact.
-
-