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After finding an amusing picture on a popular imageboard, I decided to save it. A few days past and I was browsing my images folder when I realised that the thumbnail generated by Windows XP in the thumbnails view did not match the actual image.

Here is a comparison image:

alt text

What's even stranger in this situation is that the parts of the photograph that are different have actually been replaced with what might be the correct background. Furthermore, it is a jpeg (no PNG transparency tricks) that is 343 kilobytes but only 847x847 pixels wide.

What could be going on here? Could there be anything malicious in the works, or hidden data?

Before anyone asks, I have checked and preformed the following:

  • Deleted Thumbs.db to reload thumbnails.
  • Opened image in different editors. (they appear with the text)
  • Moved image to a different directory.
  • Changed the extension to .rar.

All these steps produce the same results.

Pre actual posting update:

It seems that opening the image in paint, changing the image entirely (deleting entire contents and making a red fill) will still generate the original thumbnail, even after deleting Thumbs.db etc.

I'm also hesitant to post the original data, in case there is something malicious or hidden that could be potentially illegal. (Although it would be very beneficial to see if it works on other computers and not just my own).

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Totally unrelated, but that "X [phrase implying you should leave], you [can't/don't know] Y" is one of my favourite image memes :D –  Phoshi Mar 28 '10 at 10:46
    
It's one of the better ones. –  Sam152 Mar 28 '10 at 11:02
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1 Answer

up vote 4 down vote accepted

Spooky!

There's a good explanation, though - the jpeg specifications allow a tiny little thumbnail in the header, which is apparently not being updated by paint, but is being recognised by explorer. It's caused similar issues in the past, when people unaware of it's existance editing a picture with a thumbnail (Usually pictures taken by high-end cameras will have one), editing it, releasing it onto the internet, then wondering where everybody got the nude photos of them. Here it's a more benign case of caption-erasure, but the idea's the same. I believe Photoshop handles jpg thumbnails, have you tried that (or, maybe the GIMP), otherwise you'll need some sort of EXIF editor - but this isn't something I have a great deal of experience in, so maybe somebody else can chime in with a suggestion?

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I'm pretty relieved to read this. –  Sam152 Mar 28 '10 at 10:44
    
+1 Argg, beat me to it. I was just about to hit the submit when that annoying "another answer" banner appeared. –  Nifle Mar 28 '10 at 10:44
    
@Nifle: Oh, how I hate that banner :P –  Phoshi Mar 28 '10 at 10:45
    
Yeah, also in the meta data, the generator Paint.NET v3.36. It probably didn't create the thumbnail with the caption. –  Sam152 Mar 28 '10 at 10:46
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jhead, XnView, and many other tools can remove (and possibly regenerate) the EXIF thumbnails. –  grawity Mar 28 '10 at 17:21
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