iflPCD(3)

NAME
     iflPCD - Kodak Photo CD Image Pac file format

DESCRIPTION
     This IFL format is used to access image files on a Kodak Photo CD.  Each
     image on the CD is stored in a Kodak Photo CD Image Pac file.  On Pro
     Photo CD's higher resolution image data is stored in the Image Pac
     Extension area of the CD; this class automatically finds this data when
     asked to access the 64Base size.  A file in this format consists of
     representations of a single photographic image accessible in up to seven
     different resolutions:

            Base/64   (96x64)
            Base/16   (192x128)
            Base/4    (384x256)
            Base      (768x512)
            4Base     (1536x1024)   (optional)
            16Base    (3072x2048)   (optional)
            64Base    (6144x4096)   (in optional Pro Photo CD ipe file)

     A PCD file object represents these different resolution components as
     distinct images; the inherited iflFile member functions setCurrentImg(),
     getCurrentImg(), and getNumImgs() can be used to select and query the
     current resolution and number of available resolutions.

     The 16Base image or both the 16Base and 4Base images may be omitted from
     a Kodak Photo CD Image Pac file; the getNumImgs() member function will
     always return 4, 5, 6, or 7.  Resolutions Base/64 through Base are
     quickly accessible from the file, whereas retrieval of the 4Base and
     16Base data (if they exist) involves decompression and therefore takes
     longer per pixel to read.  Resolution 64Base is decompressed from a
     separate set of files under a directory hierarchy rooted under ../ipe
     relative to the Image Pac file holding the lower resolutions.

     The orienation of a PCD file is determined by the orientation of the
     image contents on the original film.  It will usually be
     iflUpperLeftOrigin for a landscape (wide) image, and iflLeftLowerOrigin
     or iflRightUpperOrigin for a portrait (tall) image.  In any case, the
     scan lines run along the larger dimension of the image, and the X
     dimension is always 1.5 times the Y dimension (X always varies fastest by
     definition in IFL).

     The color model of a PCD file is presented as iflRGB even though
     interanlly it is stored as iflYCC, and its data type is iflUChar.  In the
     Image Pac file, the chrominance (CC) data is usually stored at half the
     resolution of the luminance (Y) data in both the horizontal and vertical
     direction; however, IFL expands the chrominance data to match the
     resolution of the luminance if necessary, so that all three components
     appear to be at the same resolution.
     The initial resolution may be selected by appending :<n> to the filename
     passed to iflFile::open(), where <n> is the index of the desired
     resolution (0 through 6). The default is the Base resolution (index 3).

     IFL's access to a Kodak Photo CD Image Pac file is read-only; it does not
     support creation or modification of Kodak Photo CD files.

SEE ALSO
     iflFile, iflPCDO