A macOS app that converts PNG and JPEG images to Amiga IFF/ILBM format.

Drop an image, pick your settings, hit Convert. The .iff file is written next to the original.

• Classic Amiga mode -- target real hardware constraints:

  • ECS/OCS or AGA chipset limits
  • Standard screen presets (Low Res, High Res, High Res Interlace) for both PAL and NTSC
  • Fit, Fill, or Stretch resize modes
  • CAMG chunk with correct viewport mode flags
  • Deluxe Paint-compatible output

• Custom IFF mode -- no hardware constraints:

  • Any palette size from 2 to 256 colors
  • True Color (24-bit) -- 24 bitplanes, no palette, no quantization
  • No CAMG chunk, no forced resize, portrait images allowed

• Dithering -- four methods for indexed color modes:

  • Floyd-Steinberg (error diffusion)
  • Bayer 8x8 (ordered)
  • Blue Noise (stochastic)

• Median-cut color quantization with parallelized histogram, palette generation, and pixel mapping

• Image preview with drag-and-drop -- see what you're converting before you commit

The conversion pipeline has three stages:

1. Decode -- load the source image into a BGRA8 pixel buffer via CoreGraphics
2. Quantize -- reduce to a fixed palette using median-cut, then map every pixel to its nearest entry (skipped for True Color)
3. Encode -- pack into interleaved bitplane ILBM format (BMHD + CMAP + BODY chunks inside an IFF FORM)

Quantization and encoding are parallelized across available CPU cores.

• macOS 13+
• Swift 6.2+

swift run

The encoder produces standard uncompressed IFF/ILBM files compatible with:

• Deluxe Paint
• Personal Paint
• XnView, IrfanView, and other modern IFF viewers
• Real Amiga hardware (in Classic Amiga mode with appropriate settings)

For 24-bit True Color mode, the output uses 24 bitplanes (planes 0-7 = Red, 8-15 = Green, 16-23 = Blue) with no CMAP chunk.