[comp.sys.mac.hypercard] Greyscale Compression Algorithms

bhickey@micomvax.UUCP (Bruce Hickey) (08/17/88)

We are currently doing work which requires compression of greyscale images.
The emphhasis should be on speed more than on size reduction. I've heard that
hypercard performs some type of compression of the images that it uses. Is this
so? How is it done? Pointers to information or hints of any kind would be      
greatly appreciated.
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| philabs!micomvax!bhickey     Bruce Hickey, Advanced Development Group      |
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borton@uva.UUCP (Chris Borton) (08/22/88)

In article <1241@micomvax.UUCP> bhickey@micomvax.UUCP (Bruce Hickey) writes:
>The emphhasis should be on speed more than on size reduction. I've heard that
>hypercard performs some type of compression of the images that it uses. Is this
>so? How is it done? 
My understanding is that HyperCard's compression of bitmaps in the files it
saves is thanks to a nifty-wifty super-duper-secret algorithm developed by
Bill Atkinson, and Apple has done everything possible to keep it under wraps.
See the interview with Bill in the front of Danny Goodman's book.

Minor point: HyperCard compresses *bitmaps*, not grey scales.  i.e. 1 bit
 per pixel.  HC doesn't deal with more than that much yet...

-cbb
-- 
Chris Borton	borton%uva@mcvax.{nl,bitnet,uucp} 
(oops, that's rather flakey right now: use borton%uva@hasara5.bitnet)
Rotary Scholar, University of Amsterdam CS