URT File Format

• Run-length encoded (RLE) format
• Portable; files are interpreted as byte streams, no need to swap bytes between machines
• Up to 255 8-bit channels (usually 1 or 3, for 24-bit color), plus an 8 bit mask channel (called an alpha channel)
• optional Header fields
  • background color with linear slope
  • color map
  • comments (e.g. HISTORY comment shows all steps taken in generating this image)
• C interface via increasing scanlines or direct ``raw'' opcodes

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