Re: few technical questions

This is the closest that I know of:
http://www.angelfire.com/mac/kristo/documents/DCC01Paper.htm
"Application of Directional Wavelets to Image Compression"

under cons you also forgot that you have increased the amount
of data.

I guess to me it has never been if you can do this, but what are
you going to do with it once you have it?

t.


On 2002.06.17 00:26 Maciek Urbański wrote:
> 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
> 


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