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Also, image formats like JPEG have a thumbnail stored in them, which may not be updated when you edit the image.
by shinigami 12y ago
Also, image formats like JPEG have a thumbnail stored in them, which may not be updated when you edit the image.
- robin_reala 12y agoDo they? First I’ve heard of that…
- akadruid1 12y agoThe thumbnail is part of the EXIF metadata. It's reasonably well-known now, but it was not always the case... http://graphicssoft.about.com/b/2003/07/26/techtvs-cat-schwartz-exposed-is-photoshop-to-blame.htm http://graphicssoft.about.com/b/2003/07/26/techtvs-cat-schwa...
- robin_reala 12y agoHuh, interesting. Thanks!
- philjohn 12y agoA few years ago a TV presenter got caught out by this, she posted a cropped photo of herself online, but the original, uncropped version could be recovered from the file which showed her topless.
- bluedino 12y agoThere was a trend for a while of people posting images to imgur that had a totally different thumbnail. A rickroll of sorts.
- dheera 12y agoYou can use 'exiftool' on Linux to manipulate the EXIF data, get rid of the thumbnail, or set it to whatever you want. Imagemagick's 'convert' command also has a '-strip' option that will get rid of all EXIF data including any thumbnails.
- Natsu 12y agoI believe it's a Photoshop thing, rather than something common to all images. Photoshop in general does unusual things. See also: http://u88.n24.queensu.ca/exiftool/forum/index.php?topic=4514.0 http://u88.n24.queensu.ca/exiftool/forum/index.php?topic=451...
- dheera 12y agoAlso, when blacking out data from JPEGs, leave generous margins, because there may be compression artifacts in the nearby pixels that also act effectively as a one-way hash. I haven't tested how consistent these artifacts are, but it's better to be safe than sorry.