Notes

Last year I turned these notes into a more-presentable e-book. You can find the results here.

Image File Formats

Vector

• Vector formats represent images as a series of drawing instructions.
• Infinitely scalable.
• Common file type: SVG (Scalable Vector Graphics).

Raster

• Raster formats represent images as a grid of color values (pixels).

Raster File Types

• Uncompressed formats contain data for each pixel.
  • Common file types: BMP, TIFF, RAW
• Compressed formats use a compression algorithm to minimize file size.
  • Lossless vs. Lossy
    • Lossless compression algorithms contain enough information to exactly recreate the original image.
    • Common file types: PNG (Portable Network Graphics), GIF (Graphics Interchange Format)
  • Lossy compression algorithms do not retain all the details of the original image.
  • Common file type: JPEG (Joint Photographic Experts Group)

NetPBM File Formats

A family of uncompressed raster image file formats (more info).

File Type for this class: PPM (Portable PixMap)

• Pixel data is represented by RGB triplets in either ASCII or binary.
• All whitespace is equivalent.
• example file:

  P3
  4 3
  255
  255 0 0  255 0 0  255 0 0  255 0 0
  0 255 0  0 255 0  0 255 0  0 255 0
  0 0 255  0 0 255  0 0 255  0 0 255
  

• File Header
  • P3: Type of PPM, 3-btye RGB, in ASCII (P6 is RGB in binary)
  • 4 3: Width x Height, in pixels
  • 255: Maximum value per color (will scale to 255 if not 255)

Color Spaces

If you want to fall down the deep hole of color, this is a good place to start

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