Re: Human Encoding

To all the Tarkin people,

>From: Johan Hanson <[email protected]>
>Reply-To: [email protected]
>To: [email protected]
>CC: [email protected]
>Subject: Re: [tarkin-dev] Human Encoding
>Date: Mon, 22 Jul 2002 06:38:52 +0200
>
>Jeffrey Bridge wrote:
> >
> > > BTW, Im not convinced about the human mind remembering individual 
>pixels
> > > though ;).
> >
> > As far as I can tell , the mind remembers things in terms of "wall,
> > slightly bumpy texture, white" and not much more than that, at least if
> > you aren't focusing on the object. If a picture has text in it, it seems
> > that you remember the text, not the bitmap.
> >
> > As for having an encoder do one leaf texture and the decoder produce
> > lots of modified copies of it, this is totally unworkable with the
> > current state of computing.
>
>That sounds like "fractal image compression" to me. Many papers on the 
>subject
>have been produced. Use Google and ResearchIndex to find them.
>Though, I don't think existing fractal codecs do very well overall.
>
>Perhaps we should look at the "texture" aspect, trying to find a transform
>that will identify and then reproduce repeating texture patterns.
>I think DCT is better than wavelets at this. At low bitrates, good DCT 
>coders
>will cause more ringing to occur in textured areas - producing more texture 
>-
>where as a wavelet codec would just blur that area.
>For DCT, ringing is almost an intrinsic property.
>For wavelets, ringing can be said to be caused by quantization error.

Im sorry, I just couldn't stand the mention of the word 'ringing'. I hate 
ringing! While blurring is probably worse in this case, there must be a 
better way to do texture compression without any of these artifacts. 
Although Daniel Arnold pointed out that fractal compression doesn't perform 
well generally, maybe its the right thing for texutres. After all, by 
nature, textures are very repetitive: DCT and DWT just can't represent the 
repetition as well. Sigh. Maybe <shudder> ringing is better...

>I suppose that it is possible to write a wavelet-based encoder that
>produces more ringing in textured areas instead of more coefficients ...
>This may sound absurd to some, but what about an adaptive transform that
>will use the "wrong" filter lengths to intentionally produce more ringing
>artifacts in highly textured areas?
>There are coders that encode filter length as side information, and it
>does not need to have very large resolution in either space or time.

I think your idea would substantially increase the bitrate by adding more 
information. My thoughts are that there is a better algorithm out there to 
compress textures.

<snip - info about unsigned wavelets>

<snip - other wavelet style transforms: wedgelet, ridgelet, bandelet>

>--
>Johan
>
>It is half past six in the morning. I think I need some sleep now.

Dust

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