GNOME Bugzilla – Bug 118262
support inline photoshop jpeg thumbnails?
Last modified: 2003-08-25 09:27:47 UTC
So, I recently saw this page: http://www.shackspace.com/~mcbiggins@shackmail.com/cat.html which describes how some girl posted cropped JPEGs of herself to her web site, and someone else managed to extract the Photoshop-written thumbnails out of them, which show the un-cropped image in which you can see her boobs. Now, I think that's pretty funny, in a middle-school kind of way, but that's not the point. The point is, JPEGs written by Photoshop have thumbnails in them -- and GIMP does not display them, since (as far as I can tell) GIMP uses on the .xvpics version. (Right?) So, it would be nice if 1) gimp would display the thumbnails that are in the JPEG 2) gimp would save thumbnails into JPEGs, instead of / in addition to using the .xvpics directory; and maybe even: 3) provide the ability to extract the thumbs themselves (present as a special layer?) From looking at the raw file data, it looks to me like one of these is the thumbnail: Miscellaneous marker 0xe1, length 6531 Miscellaneous marker 0xed, length 7204 There's a second JFIF embedded in there, but doing the obvious thing and hacking off the part of the file before it doesn't cause it to be readable -- so perhaps it's in some strange or custom JPEG format that only Photoshop knows about? I did some searching and wasn't able to find any documentation on what kinds of stuff Photoshop puts there. What do you think?
Created attachment 18588 [details] Photoshop JPEG which contains an inline thumbnail
> What do you think? She has nice boobs.. uhh.. I mean, this sounds like a enhancement, so I'm changing the Severity and set the Milestone to future. You are asking for 3 seperate things, so this report should be split-up.
Adding this to the metadata tracking bug - the thumbnail looks to me like it's probably a standard exif thumbnail. I will check with libexif to see what I get out of it... gphoto could probably do the same thing. If it is, then we're already saving the thumbnail unchanged in the latest 1.3 builds, but we haven't been creating a metadata block to add to the image at save time for images that don't have it. I kind of agree with the Future though - doesn't look like it'll be done for a few months. That said, not that much work would be needed for this, if it is an exif thumbnail, and we could consider this for 1.3.x. I'll report back. Dave.
Just FYI, GIMP-1.3 doesn't use the .xvpics format for thumbnails any longer. Instead it implements http://triq.net/~jens/thumbnail-spec/index.html
Confirmed that this is a standard exif thumbnail. So we already do what photoshop does and keep an unaltered copy when the jpeg plug-in is linked against libexif. Just the thumbnail can be extracted using exif -e cat.jpeg. So do we want to create an exif header when saving to jpeg if one doesn't already exist? If so, what do we put in it? This is something which could be addressed as part of general exif support, or at a very basic level it could be treated separately (as I say, create an exif header with just a thumbnail, and throw it into the jpeg) - this would in fact be very easy. Since the easy thing is probably grand, I'll target this for 1.3. And this time I'm *really* adding this to the metadata tracking bug. Dave.
In terms of the original 1,2,3 I think that it would be possible o extract the thumbnail (very easily), but displaying it nicely is probably not that easy (simply put, I don't see how to display a thumbnail except as we now do, when loading an image), and we can save thumbs into the jpeg. But after extracting the thumbnail, what do we do with it? Cheers, Dave.
I think we address the most important part of this - we don't destroy the thumbnail. I don't think we should start writing exif headers. I don't think we should use possibly out-of-date thumbnails stored in exif rather than generating up-to-date thumbnails. Even if they are of attractive women topless. So I'm in favour of resolving this as a duplicate of the exif bug and be done with it. Dave. *** This bug has been marked as a duplicate of 56443 ***
Heh the support of saving unchanged exif is then actually a security problem. :-) I'll open a new bug for it.
Cross-reference: the "security issue" is tracked in bug #118384.