iflPCD(3) Image Format Library C++ Reference Manual iflPCD(3)NAMEiflPCD - 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.
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iflPCD(3) Image Format Library C++ Reference Manual iflPCD(3)
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
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