1 formats

1.1 PCX

Personal Computer Exchange

• Simple, fast, lossless
• Color palette stored in: 16 in header or 256 in the end
• Run-length encoding

1.2 BMP

Bitmap

Structure:

• File header
• Bitmap information header
• Optional palette
• Image data
• Some versions allow to define, embed or link ICC color profile

24 or 32 bpp data

• Lossless
• Colors in B G R order
• Row of data is always a multiple of 4 bytes

1.3 GIF

Graphics Interchange Format

• 256 global palette
• Multiple images in blocks
• LZW compression
• Animations

1.4 PNG

Portable Network Graphics

• Two step compression
  • pre‐compression filtering (usually improves compression)
  • dictionary compression using DEFLATE algorithm (modified LZ77)
• Up to 16-bits per RGB channel, with alpha channel
• Allows for extensions specifying absolute color space and white point, gamma correction, histograms, color profiles, pixel aspect ratio, stereoscopy and many more features

1.5 JPEG

Joint Photography Experts Group

• Lossy
• Very good compression ratio
• Bad for regular graphics (logos, shapes etc)