CSCI 107 — Representing images

The first personal computer?

• 2016 Turing award winners

Extending the photo editor

• Photoshop
  • Actions — remembers a series of steps
  • Scripts — can execute conditions, can open files
  • Plugins — manipulate images
• GIMP

More bits

• Color depth
  • Green screen, VT52 and early Mac
  • CGA, EGA and VGA
    
• Browser display statistics
• Indexed color, color palettes and web safe colors

Encoding Color

• The better known ways
  • RGB — Red, Green, Blue
  • CMYK — Cyan, Magenta, Yellow, Black
  • HSL, HSV, HSB — Hue, Saturation, Lighness or Value or Brightness
  • CIELAB or CIE L*A*B* (between the eye and brain) — lightness and color channels
• Television
  • NTSC signal encoding
  • Y’C_BC_R (used in JPEG) — Luma, Blue difference, Red difference
  • YUV (used in NTSC) — Luma and chrominance

Image formats

• TIFF — Tagged Image File Format
• JPEG — Joint Photographers Experts Group
• GIF — Graphics Interface Format
• PNG — Portable Network Graphics
• PostScript
  • as image
  • as PS
  • as EPS
• PDF — Portable Document Format

PNG — 23 kb	GIF —14 kb	JPG 11% — 24 kB	JPG 90% — 64 kB

Compressing images

• Understanding web images: JPG, GIF, and PNG | lynda.com overview
• Mathews’ tips and topics
  • Digital Image File Types Explained
  • JPG vs GIF for web images
  • Chroma Subsampling in JPG Compression
• Faked image with JPEG artifacts
• How Math led to the JPEG2000 standard
• Animation of LZW (Lempel-Ziv-Welch)

Homework 9

There an in class lab project for this week.