Quad-Tree coding of images

I) Codecs based on QT encoding

Quad-Tree based coding is often deployed for lossless coding of binary sources. Recently it has been successful used for image coding at medium bit rates. We developed two Quad-Tree based codecs for bit rates in out target range. The first codec uses only QT coding, whereas the second codec is qualitatively enhanced by and addition Parametric Codec (PC). A segmentation example for a tree structure is given here for the 'Claire' sequence. The segmentation overlayed onto the enhanced MCER or the reconstructed frame are available here and here, respectively.

The 'Miss America' Sequence
  1. The Missa Sequence , at 150 byte per frame
  2. The Missa Sequence , at 125 byte per frame
  3. The Missa Sequence , at 100 byte per frame
The 'Lab' Sequence
  1. The Lab Sequence , at 12 kbps
  2. The Lab Sequence , at 10 kbps
  3. The Lab Sequence , at 8 kbps.


II) Parametrically enhanced Quad-Tree coding

Parametric enhancement of the subjectively critical eye mouth region requires apriori knowledge at the decoder. This knowledge is available if individuals communicate more then once with each other. Otherwise the database has to be stored at the receiver which causes an initial delay.
For a successful parametric encoding, the exact location and size of the eyes has to be determined. The algorithm we developed does this difficult task with a 98 percent detection rate for our two test sequences, as one can verify for the 'Lab' or for the 'Miss America' sequence.
Once the eyes are located the database is searched for the best match, and previously stored eyes and mouth are inserted after the database entries are scaled and luminance shifted to match the actual frame. An example of a parametric coding with only 16 entries for each eye and mouth is given here .

The 'Miss America' Sequence
  1. The Missa Sequence , at 150 byte per frame
  2. The Missa Sequence , at 125 byte per frame
  3. The Missa Sequence , at 100 byte per frame
The 'Lab' Sequence
  1. The Lab Sequence , at 12 kbps
  2. The Lab Sequence , at 10 kbps
  3. The Lab Sequence , at 8 kbps.