ijpds formats.book - Kodak

Chapter 4. Record Formats
Compressed Character Definition (CCD)
Byte Position Bytes Field Name Description
37-n varies Compressed Character
Pattern
4 - 20 IJPDS Formats
Only the upright orientation is supported. Use of rotated characters
in this record will produce incorrect results.
The character pattern data for upright characters is stored
compressed and then decompressed when imaged. During
imaging, the high order bit of the first decompressed byte/word
controls the dot in the top left corner of the character bounding
box, and subsequent bits in the same decompressed byte/word
control adjacent dots in left to right order.
The compressed character pattern begins at byte position 37 and
is arranged in horizontal raster format compressed using the
compression method specified in byte positions 31 and 32. Each
row of the raster must be padded to the right with binary zeroes
(before compression) to make an integral number of 32-bit
segments. The width of the uncompressed character data (byte
positions 9 and 10) does not have to be a multiple of 32 bits but the
raster row length does.
Characters that cannot be compressed into a single CCD record must be
continued in one or more additional consecutive CCD records. The
compressed data must be divided among the continued records so that
the smallest unit of data is not divided between two CCD records. For
example, a CCD record compressed with RLEV32 must contain an
integral number of 32-bit words in the data pattern and a “run” cannot be
divided between multiple CCDs.
Should the character definition (including any continuation) contain more
or less uncompressed data than what is specified by the Height and
Width fields, the imager will display an error message and the font
download will stop. A character definition must be completed for a given
logical input RIP before any other character definitions are started.