Difference between revisions of "Run-length encoding"
(→Stack run) |
|||
| Line 8: | Line 8: | ||
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. | 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 == | + | == Stack-run based ideas == |
| + | |||
| + | === ??=== | ||
00 - 0 | 00 - 0 | ||
11 - 1 | 11 - 1 | ||
| Line 14: | Line 16: | ||
01 - run | 01 - run | ||
| + | === Alterrnating black/white runs == | ||
00 - 0 | 00 - 0 | ||
11 - 1 | 11 - 1 | ||
10 - 0 end | 10 - 0 end | ||
01 - 1 end | 01 - 1 end | ||
Revision as of 23:46, 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 - BEAR3 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 based ideas
??
00 - 0 11 - 1 10 - data 01 - run
= Alterrnating black/white runs
00 - 0 11 - 1 10 - 0 end 01 - 1 end
