ORG.SGF:

DWT

Playing with lossy and lossless image compression based on the discrete wavelet transformation

Quick start:

Encode smpte.ppm PNM picture file to encoded.dwt:

./dwtenc smpte.ppm encoded.dwt

Decode encoded.dwt file to decoded.ppm picture file:

./dwtdec encoded.dwt decoded.ppm

Watch decoded.ppm picture file in feh:

feh decoded.ppm

Limited storage capacity

Use up to 65536 bits of space instead of the default 0 (no limit) and discard quality bits, if necessary, to stay below 65536 bits:

./dwtenc smpte.ppm encoded.dwt 65536

Use different wavelet

Use the reversible integer Haar wavelet instead of the default 1 CDF 9/7 wavelet for lossless compression:

./dwtenc smpte.ppm encoded.dwt 0 2

Reading

• Run-length encodings
  by Solomon W. Golomb - 1966
• Image coding using wavelet transform
  by M. Antonini, M. Barlaud, P. Mathieu and I. Daubechies - 1992
• Factoring wavelet transforms into lifting steps
  by Ingrid Daubechies and Wim Sweldens - 1996