Re: [CinePaint] jpg worse
Frank Peters <[email protected]>
| Newsgroups | gmane.comp.video.cinepaint.user |
|---|---|
| Message-ID | <[email protected]> |
On Fri, 14 Mar 2008 19:36:10 +0200 Rob Lingelbach <[email protected]> wrote: > > On Mar 14, 2008, at 6:54 PM, Frank Peters wrote: > >> > >> No. There should be no discernable difference when a > >> file is saved as a JPEG -- unless the quality factor > >> is set to some extremely low value. > >> > > then perhaps I've got my signals crossed- I thought a camera RAW file > was essentially without compression, whereas a JPEG file, even when > set to 100% quality factor, still had compression, which can be seen > particularly in a repeating pattern. > JPEG compression is based on the discrete cosine transform which eliminates the high frequency spatial components that are less noticed by human perception. In the majority of cases the results of JPEG compression should be indistinguishable from the original, but there are certainly some special cases -- such as very high frequency patterns perhaps -- where the artifacts are more noticable. But even then it would take a discering eye to notice them. In general, however, it wouldn't be expected that JPEG compression would heavily degrade an image to the extent that you describe. Frank Peters ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/