semmixcolor and perception

Color theory: contents

Four parts, from the basics of color perception to the structure of an image file. The topics can be read in order, but each one also stands on its own.

Topics shown in gray are in preparation.

Colors and models

What color is, how the eye sees it and how color space models describe it.

  1. Introduction: light, color, model
  2. Selected historical facts
  3. Model of the eye
  4. RGB model
  5. CMY and CMYK models
  6. Device-dependent models
  7. Color mixing
  8. Color measures
  9. Brightness
  10. Intensity
  11. Saturation
  12. Luminance
  13. Lightness
  14. HLS and HSI models
  15. CIE XYZ model
  16. CIE 1931 white points
  17. Television models YUV and YIQ
  18. CIE derivatives: LUV and LAB
  19. HSV and HSB models
  20. Notes on the models

Conversions between models

Formulas and algorithms for converting colors between models, with worked examples.

  1. RGB, CMY and CMYK
  2. Hue angle to RGB
  3. Helper functions
  4. RGB to hue angle
  5. HLS and RGB
  6. HSI and RGB
  7. HSV, HSB and RGB
  8. CIE XYZ and RGB

Elements of image description

How an image file describes a picture: pixel aspect, palette, color depth, gamma, transparency, compression.

  1. Introduction
  2. Pixel aspect ratio
  3. Color palette
  4. Color resolution
  5. Gamma correction and color management
  6. Color transparency
  7. Interlacing
  8. LZW algorithm
  9. LZW compression
  10. LZW decompression

The GIF format step by step

The structure of a GIF file byte by byte: header, blocks, extensions and LZW compression.

  1. Introduction
  2. General structure
  3. Header
  4. Logical screen descriptor
  5. Image block ($2C)
  6. Extension blocks ($21)
  7. Plain text extension ($01)
  8. Graphic control extension ($F9)
  9. Comment extension ($FE)
  10. Application extension ($FF)
  11. Block order
  12. LZW algorithm in GIF
  13. LZW compression in GIF
  14. LZW decompression in GIF