[ILUG] wavelet compression

[John P. Looney]

On Tue, Apr 18, 2000 at 09:49:43PM -0400, D ONeill mentioned:
> JPEG's are lossy by nature. Try scanning a good quality image & then
> save as an .lwf --- I don't think you'll see the degradation you did on
> the JPEG. You also asked about text & binaries. Lura have a proggie for
> docs with text/grapics mixed,  but it's very dear ($3,250) and is only
> available for Win or Mac.

 I tried this yesterday. I got Joe here to take a few photos with a
digital camera, and to turn off compression. This made a few 6MB images.

 Running JPEG at 75% quality didn't have much of a noticeable affect on
quality, but brought the image down to 300k. Running the Wavelet stuff on
it, at a similar quality, produced an image of 288k. 

 The wavelet stuff didn't really start to get better till I told it "Use
10k for data". It produced a very blurry image, that was quite
recognisable. JPEG, at quality 1% will go as low as 30k, and it looks
terrible.

 Wavelets aren't much better than JPEG at medium compression, but at high
compression they rock. Though the value of compressing a large image down
to something tiny, is questionable, considering that though the quality of
Wavelets is better than JPEG, even before it gets to the "Too poor to be
of use to me", it's not that much better. It's at the "Too poor to be
useful" stage - and only then - that Wavelets are significantly better.

Kate

-- 
"The fool must be beaten with a stick, for an intelligent person 
the merest hint is sufficient"                -- Zen Master Greg