X-Mozilla-Status: 0001 X-Mozilla-Status2: 00000000 Message-ID: <36BDD146.295B7E8F@concentric.net> Date: Sun, 07 Feb 1999 12:45:42 -0500 From: Eric Durant X-Mailer: Mozilla 4.5 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: microsoft.public.frontpage.client Subject: Re: jpgs save twice and get "fuzzy" References: <36BB5F8D.21FDFD0D@stumpstoneware.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit S Lee wrote: >The reason it is getting fuzzy, is because the way you are doing >it, FP keeps re-saving the image. And jpg files are 'progressive' >- each time they are saved, some compression of information takes >place. Hence the deterioration in quality. Actually, the progressive encoding feature of JPEG, which is an option, isn't the key factor here. The degradation is caused by the quantization, that is, the discarding of less important image data in order to produce smaller files. If an image is loaded and saved in JPEG format without making any changes, and the exact same quality factor is used, no change (i.e. no further degradation) should occur. This is limited by the accuracy of the encoding and decoding algorithms used (specifically the round-off error in the DCT/IDCT). Experimenting with LView Pro 1.D2 shows that the quality stabilizes after the first JPEG save, and the effects of resaving have negligible affects on the outcome (with the requirements that no edits are made to the image and the same encoding options, including quality factor, are used), at least for 10s of resaves. I haven't done the same test with FrontPage's JPEG ability.