From Worms Knowledge Base
(Up to File formats)
Team17's image files (typically with an .img file extension) are usually compressed palleted images.
- 4-byte signature - "IMG\x1A"
- complete file length (4 bytes)
- optionally, a null-terminated string describing the image (present only in some Worms 2 images)
- the number of bits per pixel in the image (usually 8) (1 byte)
- image flags (1 byte)
- if the image has a palette (highest flag bit is set):
- the image width (2 bytes)
- the image height (2 bytes)
- the image data. If the data is compressed (the corresponding image flag is set), see Team17 compression for the decompression routine; otherwise, it's just an array (Width × Height).
The flag byte is a bit field of the following values:
- 0x40 (01000000) - set if the image data is compressed
- 0x80 (10000000) - the image has a palette
- The black colour isn't listed in the image palette, nor counted in the "number of colours" word. It is counted as the colour 0, so the palette stored in the file should be loaded starting from colour 1.
- Embedded images in WWP land.dat files align their data by 4 bytes.