Binary image compression

• Run-length coding (used in FAX, PCA, etc.)

  Represent each contiguous group of 1's or 0's encountered in a row (left to right) by its length. Two ways to implement:

  • Specify whether the first run is 1 or 0
  • Always assume the first run is 1 or 0
  The run-length can be further encoded by Huffman coding.

• Quad-tree
  • Represent the binary image by a quad-tree.
  • Traverse the quad-tree in a certain order (pre-, in- or post-order)
  • Encode each black block