> Can you clarify where this file is when you do CTRL+S ? You say you
> open "directly from the camera" , do you mean you are opening a file
> that is still on the camera ?!
My camera stores the pictures in a Compact Flash card. I use a card reader.
I copy those files to my hard drive, then I open them with gimp (or
gthumb for viewing.)
Sometimes I open them directly from the CF card, but it's almost the
same, it's a storage medium anyway.
> I have not checked the source code but I would expect gimp to retain
> the existing quality setting of the image defined in the jpeg header,
> in this case determined by you camera. If you can demonstrate this is
> not happening it probably needs checking.
That's precisely what I was trying to say.
Is it possible that the quality setting defined in the jpeg header by
the camera isn't in the IJG scale?
(excuse my ignorance... I don't know how the file is structured).
If that happens, is it possible that Gimp is taking the wrong setting as
reference from the file?
> If you want to choose a different compression you should be using File
> | Save As rather than File | Save .
Yes, I'm doing that now. But I learned that in the tough way :-)
> You also say "when I take my image to PS from my camera" , could you
> me more precise about the operations you are using? Are you opening a
> file on the camera , are you removing it from the camera and putting
> it elsewhere with this operation, when you CTRL-S in PS where does it
> get saved, back to the original file or elsewhere on your disk?
1- take the photo.
2- put the card in the reader and copy the photo to the disk.
3- open it with the image manipulation program
4- save it using CTRL+S
In Gimp, it saves the file directly, without asking for the compression
setting. Result: an image over-compressed with artifacts. Smaller size
than the original.
In Photoshop, it shows the quality settings the first time you hit CTRL+S.
> As I said in my last post Øyvind's test shows there is an issue with
> degradation on multiple resaves , I dont think this caused by
> 'quality' parameter being changed.
> You may have picked a bug and you are misinterpreting this as a change
> in the compression.
Yes, I think so. At first I thought it was a quality setting issue, but
since I learned how the IJG scale works I'm convinced that is a bug or,
at least, a strange behaviour.
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