This project consists of 2 command line utilities:

• iff2bpl Converts ILBM (Interleaved Bitmap) IFF files to Amiga bitplane format and 8-bit chunky format.
• bpl2iff Converts Amiga raw bitplane format to ILBM (Interleaved Bitmap) IFF files (note: currently palette has all colours other than 0 fixed to $FFF)

This tool converts IFF image files into formats suitable for Amiga applications:

• Raw bitplane data (.bpl) - Interleaved format for Amiga hardware (default)
• Palette data (.pal) - 16-bit words in Amiga colour register format
• Chunky pixel data (.chk) - 8-bit per pixel chunky format (optional)
• Non-interleaved planar data (.bpf) - All rows of plane 0, then plane 1, etc. (optional)

• Converts ILBM (IFF) files to Amiga-compatible formats
• Supports both compressed (RLE/PackBits) and uncompressed IFF files
• Generates Amiga hardware-ready bitplane data
• Converts 8-bit RGB palette to 4-bit Amiga colour format
• Optional chunky format output for software-based pixel manipulation
• Optional non-interleaved planar format for specific development needs
• Custom output filename support
• Minimal dependencies - compiles with standard C libraries

iff2bpl [-o output_name] [-c] [-cd] [-ni] <input.iff>

• -o output_name - Specify custom base name for output files
• -c - Also create chunky format output (.chk file)
• -cd - Also create chunky format with bit doubling (.chk file)
• -ni - Also create non-interleaved planar format (.bpf file)
• <input.iff> - Input IFF/ILBM file to convert

# Basic conversion - creates image.bpl and image.pal
iff2bpl image.iff

# Custom output name - creates sprite.bpl and sprite.pal
iff2bpl -o sprite image.iff

# Include chunky format - creates image.bpl, image.pal and image.chk
iff2bpl -c image.iff

# Include non-interleaved format - creates image.bpl, image.pal and image.bpf
iff2bpl -ni image.iff

# Combined options - creates sprite.bpl, sprite.pal, sprite.chk and sprite.bpf
iff2bpl -c -ni -o sprite image.iff

# Include chunky format with bit doubling - creates image.bpl, image.pal and image.chk
iff2bpl -cd image.iff

Raw bitplane data in interleaved format ready for Amiga hardware. Each bitplane contains one bit per pixel, organized in the format expected by Amiga's custom chips.

Palette entries converted from 8-bit RGB to 4-bit Amiga format, stored as 16-bit words compatible with Amiga colour registers.

Optional 8-bit per pixel format where each byte represents a complete pixel value (palette index). Useful for software-based pixel manipulation or conversion to other formats.

Optional planar format where all rows of each bitplane are grouped together (plane 0 data, then plane 1 data, etc.) rather than interleaved by scanline. Useful for certain development workflows or tools that expect this data organization.

The -cd option creates chunky data where each bit of the 4 least significant bits is expanded to 2 bits by replication. This effectively converts 4-bit color values to 8-bit values. This is useful with a particular class of C2P routines (up to 16 colours) which require such input.

Examples:

• 00000001 becomes 00000011
• 00000010 becomes 00001100
• 00001101 becomes 11110011

gcc iff2bpl.c -o iff2bpl.exe

Use the included VS Code configuration files for building and debugging.

• Standard C compiler (GCC, Clang, MSVC)
• Standard C libraries (stdio, stdlib, stdint, string)

bpl2iff converts raw Amiga planar bitplane data into an ILBM IFF file (FORM/ILBM) containing the BMHD, CMAP and BODY chunks. It supports interleaved and non-interleaved input, an optional byte-column transpose mode (-t) and optional PackBits (RLE) compression of the BODY chunk (-r).

The CMAP chunk created by bpl2iff contains 2^n entries where n is the number of bitplanes.

• If a palette of the matching number of colours is found at the end of the file (2^n * 2 bytes) then it is converted to the CMAP.
• Otherwise the first palette entry is set to black (00,00,00) and all other entries are set to white (FF,FF,FF).

bpl2iff -x <xsize> -y <ysize> -n <bplnum> [-i] [-t <colwidth>] [-r] -o <output_name> <input_file>

Parameters:

• -x <xsize> : horizontal size in pixels (required)
• -y <ysize> : vertical size in pixels (required)
• -n <bplnum>: number of bitplanes (required)
• -i : input is interleaved rows per plane (optional)
• -t <colwidth>: input is stored in byte columns of specified width and must be transposed first (optional)
• -r : compress BODY with PackBits (RLE) (optional)
• -o <output_name>: base name for output file (will have .iff appended if missing) (required)
• <input_file>: path to raw input file (required)

gcc bpl2iff.c -o bpl2iff.exe

There are small test inputs and helpers in the tests/ folder. See tests/README.md for details.

Conversion of 8x8 1-bitplane fonts:

./bpl2iff.exe -x 768 -y 8 -n 1 -t 1 -r -o ./tests/fonts8.iff ./tests/fonts8.fnt

This will create fonts8.iff which should be a 1-bitplane, RLE compressed font file.

Conversion of 16x16 1-bitplane fonts:

./bpl2iff.exe -x 1536 -y 16 -n 1 -t 2 -r -o ./tests/fonts16.iff ./tests/fonts16.fnt

Conversion of a 320x200 5-bitplane (interleaved) raw picture with a palette attached at the end:

./bpl2iff.exe -x 320 -y 200 -n 5 -r -i -o ./tests/dead.iff ./tests/dead.rawb

Copyright (c) 2025 Kane/Suspect
Licensed under the GNU GPLv3 License.