Date: Sun, 08 Jul 2007 11:44:17 +0200 From: gg@xxxxxxxxxxx On Sun, 08 Jul 2007 07:22:24 +0200, Guillermo Espertino <gespertino@xxxxxxxxx> wrote: > 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. I think we're finally getting closer to the truth. There is something non standard in the file the camera is producing. It seems that PS knows there's a problem and thus prompts for the quality parameter, gimp it would seem is either reading this value as the IJG quality when it isn't or is applying a not too good default when it fails to read it. If it's an incorrect value put in by the camera that gimp is correctly reading it's not a gimp issue. If it is a missing value gimp should probably use it's jpeg default of 85 (or prompt as you suggest) which it does not seem to be doing. If you have imagemagick installed, use the following to see what information is in one of your camera images before you affect it with either gimp or ps and then again after gimp (and/or PS) does a save on it: identify -verbose unadulterated_image.jpeg That should give some info on what is in the jpeg header. This appears to be the case. The original image gives me this: $ identify -verbose /images/dcim/193canon/img_9309.jpg Image: /images/dcim/193canon/img_9309.jpg ... Filesize: 2.96358mb ... Compression: JPEG Quality: 98 Orientation: LeftBottom JPEG-Colorspace: 2 JPEG-Sampling-factors: 2x1,1x1,1x1 However, when I save it out, it's clearly not using the original quality setting: $ identify -verbose /tmp/img_9309.jpg Image: /tmp/img_9309.jpg ... Filesize: 901.654kb ... Compression: JPEG Quality: 85 Orientation: TopLeft JPEG-Colorspace: 2 JPEG-Sampling-factors: 2x2,1x1,1x1 If I explicitly save it out using the same settings as what came from the file, I wind up with a slightly shrunk file: $ identify -verbose /tmp/img_9309.jpg Image: /tmp/img_9309.jpg ... Filesize: 2.65972mb ... Compression: JPEG Quality: 98 Orientation: TopLeft JPEG-Colorspace: 2 JPEG-Sampling-factors: 2x1,1x1,1x1 Note that GIMP is not the only application that does this; KPhotoAlbum also changes the quality setting (to 75!). In this case, I suspect that it simply doesn't tell the appropriate library what the actual quality setting is from the original file. -- Robert Krawitz <rlk@xxxxxxxxxxxx> Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 Member of the League for Programming Freedom -- mail lpf@xxxxxxxxxxxx Project lead for Gutenprint -- http://gimp-print.sourceforge.net "Linux doesn't dictate how I work, I dictate how Linux works." --Eric Crampton _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
