few technical questions

For a long time i've wanted to write a wavelet video codec, and now, after a
brief (2 years) papers-gathering-and-reading phase I'm about to start. ;-)
So be ready for large amount of posts from me ;-)

Idea of the day:

The the easiest way to experiment with a wavelet transformation is to write
a filter for Avery Lee's VirtualDub (Windows only). This way you can feed
large amount of video data to your kernel and see how it behaves.


Wavelet idea of the day:

The current research in wavelet transform area focusses on incorporating
"directionality" or "multi-directionality" into wavelet transform.
Traditional 2D wavelet transform is builded by one 1D transform in
horizontal and one 1D transform in vertical direction. After each transform
signal is divided into two parts: the part with only directional information
(vertical or horizontal) in some resolution, and the part without it.
Traditionally we treat the parts as a differencies and sums.
After wavelet transform of image we have 4 images, sums, vertical
differencies,  horizontal diferencies, and vertical diferencies of
horizontal diferencies, each with half of width and height of original.
I propose an extension of this approach: after 2-level 1D transformation,
 one - and one | ), the next transform on entire 4-images-block follows:
exactly the same transform but in \ and / directions. \ transform processes
data in diagonal direction eg. [0,0] then [1,1], then [2,2], etc. The /
transform processes data in other-diagonal direction eg. [2,0], then [1,1],
then [0,2]. They both are exactly normal wavelet transform.
In result we have 16 bands each with signal of different directionality.
pros:
    - ganthers signal in more directions
    - quantization errors are more dispersed
    - it's simple
cons:
    - stepping in diagonal direction is rather cache un-fiendly
    - it's hard to use interlaved block adressing with it
    - entire transformation is 2x slower

Please, post your comments.

Maciej


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