[gs-devel] How to tell when DCTEncode is OK? (re #450663)
L. Peter Deutsch
ghost at aladdin.com
Wed Apr 10 17:01:48 PDT 2002
> Encode source data, decode the result and compare 2nd result with source
> Image is a vector of color components, so the comparison is a norm and a
> Not sure which norm is best though.
> Not sure if it is fast enough.
I think simply using a threshold for the difference is not sufficient. One
of the typical bad results from inappropriate DCT encoding of is a lot of
faint "speckling" in the decoded image. The individual differences are
small: it's the loss of monotonicity that is objectionable.
I liked Raph's suggestion and will try using it when I get around to this
L. Peter Deutsch | Aladdin Enterprises | 203 Santa Margarita Ave.
ghost at aladdin.com | http://www.aladdin.com | Menlo Park, CA 94025
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