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1. Re: show jpeg-kompression
dave milbut Feb 21, 2008 5:12 AM (in response to McMaster05)>Is it possible to see what kompression-settings were made when a jpeg was saved?
nope.
>When Saving you get that 0-100%-Slider. When I save an image with for ex. 60%, can I find out wheather it was 60% or 70% after saving?
what if the saving app didn't use 0-100% what if it used 1-10? or some other range (0-300)?
bottom line. no, you can't tell. once it's saved it's saved. that data isn't retained anywhere. -
2. Re: show jpeg-kompression
McMaster05 Feb 21, 2008 5:43 AM (in response to McMaster05)Ok, thanks, good to know... -
3. Re: show jpeg-kompression
Bart Cross Feb 21, 2008 6:17 AM (in response to McMaster05)to add to wat dave said, the compression is relevant to the image. -
4. Re: show jpeg-kompression
Guest Feb 21, 2008 9:09 AM (in response to McMaster05)
Nobody knows the 'settings', but one can draw
some conclusions:
1. the compression ratio Oldfilesize/Newfilesize
for somewhat average photos:
5..10 optimal quality
20..30 average quality
>40 rather bad quality
2. accessible only for programmers: the content
of the so-called quantization tables
The program Quite a Box of Tricks by
http://www.quite.com
delivers quality/compression comments for JPEGs
in PDFs.
Such an information is very helpful for analyzing
the compression state: resolution in ppi, kind of
color space, kind of compression, for JPEGs: which
quality.
Best regards --Gernot Hoffmann -
5. Re: show jpeg-kompression
Рipkin Feb 21, 2008 12:41 PM (in response to McMaster05)That's not bad: jpgQ - JPEG Quality Estimator (freeware) - http://www.mediachance.com/digicam/jpgq.htm -
6. Re: show jpeg-kompression
McMaster05 Feb 22, 2008 1:13 AM (in response to McMaster05)Cool, many thanks... -
7. Re: show jpeg-kompression
dave milbut Feb 22, 2008 5:12 AM (in response to McMaster05)from that site:
>Loss is adding up but not as many people think - if we use twice 75% first time then 75% second time it doesn't mean that the second round is equal to 55% of original quality (75% of first 75%). There is some loss but far less. So it doesn't work like your taxes.
as far as i know from what i've read, it does indeed give you 75% of quality EACH time you save. so with an assumption that flawed (assuming that i'm right, which is not always true <g>), how will his software "estimate" anything correctly?


