Difference between revisions of "Run-length encoding"
(→Stack run) |
(→Amiga - IFF - RLE compression) |
||
| Line 3: | Line 3: | ||
== Amiga - IFF - RLE compression == | == Amiga - IFF - RLE compression == | ||
| − | One or more bit planes. Runs longer than 2 bytes are encoded as -1 to -127 followed by the byte to be repeated (-n) + 1 times. | + | One or more bit planes. Runs longer than 2 bytes are encoded as -1 to -127 followed by the byte to be repeated (-n) + 1 times. Runs of different bytes are stored as 0 to 127 followed by n + 1 bytes of data. The byte code -128 is a no operation. |
== Head-On - BEAR2 compression == | == Head-On - BEAR2 compression == | ||
Revision as of 23:29, 27 January 2011
Contents
Atari ST - Savage Paint - PAC compression
Single bit plane. The five most common bytes in the image was followed by a run length byte. It was simpler and gave higher a compression ratio than the run-length algorithm used in the .IFF format on the Amiga. The reason for using the 5 most common bytes was mainly because of the number of free registers in the MC68000 CPU.
Amiga - IFF - RLE compression
One or more bit planes. Runs longer than 2 bytes are encoded as -1 to -127 followed by the byte to be repeated (-n) + 1 times. Runs of different bytes are stored as 0 to 127 followed by n + 1 bytes of data. The byte code -128 is a no operation.
Head-On - BEAR2 compression
Indexed graphics, 8 bits per pixel. The range 0 to n was used by pixel data. The range n + 1 to 255 was the run lengths. Run-length = (byte - n) + 1. The main goals were fast, simple and compressible with ZIP for distribution.
Stack run
00 - 0 11 - 1 10 - data 01 - run 00 - 0 11 - 1 10 - 0 end 01 - 1 end
