Message-Id: <mailto:199607081357.IAA25542@library.wustl.edu> Date: Mon, 8 Jul 1996 09:06:36 -0500 From: Kurt Foss <mailto:kfoss@JOURNALISM.WISC.EDU> Subject: Re: Lossy compression To: Multiple recipients of list IMAGELIB
At 11:55 PM -0500 7/7/96, Jennifer Brasher wrote:> I've heard from a photographer that repeated compression/decompression
> with Photoshop using JPEG caused loss of image data?
---There are a lot of factors that ought to be included when making any such judgment, based on my experiences and testing results I have seen. If the compression ratio is changed each time, then of course you'd expect to see serious image degradation. If you're *not* changing those sorts of quality settings, you should not see any successive changes in quality. But then WHY would you be re-compressing -- that's the question I am wondering here. Could you give me an example of such a situation just for discussion's sake?
rgds ~ Kurt
>--- KURT FOSS <! -- ~k --> U_of Wisconsin-Madison * School of Journalism and Mass Comm. 5020 Vilas Communication Hall * 821 Univ. Ave. * Madison, WI 53706 Email: mailto:kfoss@journalism.wisc.edu * kfoss@emrg.com * CIS: 70541,1040 Phone: W 608.263.3391 or .4080 * FAX 262.1361 * H 271.1210 mailto:ONline@UW-Madison <http://www.journalism.wisc.edu/> Technology Editor, EPW8 <http://sunsite.unc.edu/nppa/epw8home.html> Assoc. Ed., Photo District News <http://www.pdn-pix.com> <!-- # -->