Apple introduced the PackBits format with the release of (Click link for more info and facts about MacPaint) MacPaint on the (A waterproof raincoat made of rubberized fabric) Macintosh computer.
This compression scheme is one of the types of compression that can be used in (A quarrel about petty points) TIFF-files.
This Technote describes the format of data packed by the Toolbox utility PackBits and documents a change to the srcBytes limit and to the possible worst case.
PackBits never generates the value -128 ($80) as a flag-counter byte, but a few PackBits-like routines that are built into some applications do.
PackBits packs the data only when there are three or more consecutive bytes with the same data; otherwise it just copies the data byte for byte (and adds the count byte).
Files with none, LZW, or PackBitscompression are supported, as well as those with some other compression schemes.
The supported classes have a variety of possible compression schemes of which JPEG, LZW, PackBits, CCITT 3 Fax, and CCITT 4 Fax are known to work.
It is also possible append the attribute WORLD to the option value, separated from other text by a space, in order to request that an Arc/Info style TIFF World file be generated.
TIFF extensions include support for other pixel types and depths (signed integers and floating point values, for instance) and alternate compression schemes.
The plugin only writes uncompressed images or images compressed with the packbits scheme.
Usage: drgtool grid [options] infile [outfile] Function: grid draws a UTM grid on a map Options: -c {lzw, zip, packbits, none} Compression type default is to use same as input file -q Be quiet -r Replace input file with output
Usage: drgtool join [options] infile1 infile2 outfile Function: join seamlessly joins two DRG maps Options: -c {lzw, zip, packbits, none} Compression type default is to use same as input file -f Create.fgd file for joined map -n "Map Name" Set map name to that specified -q Be quiet -r Replace existing file with output
Files are packbitscompressed as distributed from USGS.
infomesa.com /~msw/drgtools (1191 words)
Pbmtolj User Manual(Site not responding. Last check: 2007-10-20)
Prevents pbmtolj from writing the reset sequences to the beginning and end of the output file.
Enables use of both TIFFpackbits, and delta-between-rows compression.
This option controls the "number of copies" printer control; pbmtolj generates only one copy of the image.
Man page of BMP2TIFF(Site not responding. Last check: 2007-10-20)
image is created with data samples packed (PlanarConfiguration=1), compressed with the PackBits algorithm (Compression=32773), and with each strip no more than 8 kilobytes.
Specify a compression scheme to use when writing image data: -c none for no compression, -c packbits for the PackBitscompression algorithm (the default), -c jpeg for the baseline JPEG compression algorithm, -c zip for the Deflate compression algorithm, and -c lzw for Lempel-Ziv and Welch.
Write data with a specified number of rows per strip; by default the number of rows/strip is selected so that each strip is approximately 8 kilobytes.
BitInputStream, BitOutputStream : Convert a bit stream into a byte stream (vice versa).
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