BMP — Bitmap (Non-Standard)

Custom compressed image format. Does NOT use the token-based binary encoding. This is completely independent.

Header

Offset	Size	Type	Description
0	1	byte	Encoding type
1	1	byte	Palette size (entries = value + 1)
2	2	int16	Width
4	2	int16	Height
6	varies	BGR × palette	Color palette (if palettized)

Encoding Types

Value	Hex	Mode	Description
4	0x04	Palette 4-bit	16-color palette, 2 pixels per byte
8	0x08	Palette 8-bit	256-color palette, 1 pixel per byte
152	0x98	Direct RGB	3 bytes per pixel, no palette

Palette Colors

Stored as BGR (blue first, then green, then red) — 3 bytes per entry.

Pixel Data Compression (RLE)

After the palette, pixel data is stored in compressed blocks:

1. Read blockLengthDecompressed (int16) and blockLengthCompressed (int16)
2. If equal → raw copy
3. If different → RLE decompression using a bitmap-driven sub-block scheme:
   • Read a blockMap byte — each bit controls one operation
   • Bit = 0 → copy next byte literally
   • Bit = 1 → RLE: read lookback distance + repeat count, copy from earlier in buffer

The RLE algorithm was reverse-engineered by Sluicer.

Read/Write Support

Read only. No encoder implemented.

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