From: Dave 

On Thu, 7 Jul 2005 07:42:17 +0300, "Antti Kurenniemi"
 wrote in message
:

| It's not "hidden data", but AFAIK the jpg format allows a
thumbnail to be | included in the file - so the thumbnail you see is not a
shrinked version of | the actual image file, but it can even be a
completely different image. In | this case the thumbnail was probably
created from the image before obscuring | the face from the actual image.
|
| Some viewers allow you to see / modify this thumbnail, but I've never
played | with it myself so I can't name any right now. |
|
| Antti Kurenniemi
|
| "Dave"  wrote in message |
news:k3bpc1t60rgid3nlgf0m46mcu2b1in5hu9{at}4ax.com...
| >I was searching for some old pictures tonight, paging through the
| > thumbnails in Windows Explorer, when I noticed some anomalies --
| > sometimes for cropped or edited images, the thumbnail shows the full
| > frame or the unedited version of the image.  In one instance, where
| > the face of a subject was obscured in the full size image, the face
| > was visible in the thumbnail.
| >
| > Is there any sure-fire method for viewing this kind of hidden data in
| > .jpg files?  Or for double-checking your own images before posting
| > them in public to make sure there is no hidden information that
| > someone else may be able to see?
|
Well in one case the image in question is a photograph I took myself, on
film, and had the processors make a Photo-CD.  I cropped and re-sized the
image in Irfanview, but the thumbnail shows the un-cropped image.

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