iratahack / bmp2tilecompressors

Compression DLLs for BMP2Tile

bmp2tile-compressors

Compression DLLs for BMP2Tile

Overview

BMP2Tile supports plug-in compressors, somewhat inspired by Winamp. This repo holds all the ones I've written, plus some that were contributed by others. As far as is possible, I try to also include decompressors for use in homebrew and ROM hacks.

Releases

Automated builds are available on the Releases page.

Compressors

DLL name	Short name	Longer name	Description	Tiles supported	Tilemap supported
1bppraw	1bpp	1bpp raw (uncompressed) binary	One bit per pixel tiles - discards upper bits	✅
2bppraw	2bpp	2bpp raw (uncompressed) binary	Two bits per pixel tiles - discards upper bits	✅
3bppraw	3bpp	3bpp raw (uncompressed) binary	Three bits per pixel tiles - discards upper bit	✅
aPLib	aPLib	aPLib	aPLib compression library	✅	✅
apultra	apultra	aPLib (apultra)	apultra aPLib compressor - better compression for the same format	✅	✅
exe	(configurable)	(configurable)	Wraps arbitrary external programs, passing data via files. This is useful if you do not want to implement your algorithm in the form of a DLL.	✅	✅
exomizerv2	exomizer	Exomizer v2	Exomizer v2 compression ⚠ Seems to crash on some inputs	✅	✅
highschoolkimengumi	hskcompr	High School Kimengumi RLE	Compression from the game High School! Kimengumi	✅	✅
lsb	lsbtilemap	LSB-only tilemap	Least significant byte of tilemap data		✅
lz4	lz4	LZ4 (raw)	LZ4 compression library	✅	✅
lzsa1	lzsa1	LZSA1	LZSA compression library	✅	✅
lzsa2	lzsa2	LZSA2	LZSA compression library	✅	✅
oapack	oapack	aPLib (oapack)	oapack aPLib compressor - better compression for the same format	✅	✅
phantasystar	pscompr	Phantasy Star RLE	Compression from the game Phantasy Star	✅	✅
psgaiden	psgcompr	PS Gaiden	Compression from the game Phantasy Star Gaiden	✅
pucrunch	pucrunch	Pucrunch	Pucrunch algorithm	✅	✅
raw	bin	Raw (uncompressed) binary	Does no compression at all	✅	✅
sonic1	soniccompr	Sonic 1	Tile compression from the game Sonic the Hedgehog	✅
sonic2	sonic2compr	Sonic 2	Tile compression from the game Sonic the Hedgehog 2	✅
stc0	stc0compr	Simple Tile Compression 0	@sverx's stc0	✅
zx0	zx0	ZX0	ZX0 compression library	✅	✅
zx7	zx7	ZX7 (8-bit limited)	Variant of ZX7 compression library tweaked for performance	✅	✅

Decompressors

All are for emitting data direct to VRAM on Master System, using Z80 decompressors. Decompression to RAM will generally be smaller.

Description	ROM (bytes)	RAM (bytes, not including stack)
aPLib	303	5
aPLib (fast)	333	0
Exomizer v2 (⚠ Broken)	208	156
LZ4	136	0
LZSA1	207	0
LZSA2	332	0
Phantasy Star RLE	188	0
PS Gaiden	223	34
PS Gaiden (fast)	1028	32
Pucrunch (⚠ Broken)	412	44
Sonic	162	8
Sonic 2	289	39
ZX0	157	0
ZX0 (fast)	274	0
ZX7	117	0

Note that the technologies marked with ⚠ above fail the automated benchmark tests, with crashes in the compressor or incorrect decompressed output. They could be fixed but as they are rather old, they are probably not competitive with newer compressors.

Benchmark

Based on a benchmark corpus made of tilesets and title screens, here's a scatter of the results.

How to read:

• Further to the right is faster
• Further up is better compression
• The scatter for a particular colour group is across a corpus of realistic Master System tile data
• Each colour group has an ellipse showing the standard deviation, with a + in the middle showing the mean, across the test corpus.

There can be wide variation in performance between compressors depending on your data; you may want to try a few options for your specific use case.

Other compressors

Here's some other compressors people have made.

Name	Link	Description	Tiles supported	Tilemap supported
ShrunkTileMap	https://github.com/sverx/STMcomp	Compresses tilemaps with specific support for sequential tile indices		✅