Thumbnail is different from full image - can I get the image in the thumbnail?

Factual Questions
1

I am on an Intel Macbook running OSX 10.5.8.

I saved a jpg image from the Internet and the thumbnail in my file browser appears to be from a larger image that the jpg I have is cropped from. I remember hearing about a scandal a few years ago in which a television presenter (perhaps one from G4TV?) posted an image that was revealed in some manner to be a crop of a nude photo, and that using some program, people were able to extract the original photo.

Am I misinformed? How did they do it? Can I do it with a program such as Photoshop? Where is the file that determines what image will be shown in the thumbnail?

I’ve taken a screenshot in order to show what I mean. The thumbnail appears on the left and is titled deepred.jpg. It appears to be a photo showing all four members of the band, the Manic Street Preachers. The image itself is on the right, cropped to only one of the four people in the original photo.

2

When you put images on a Web site, you can either shrink down an image using HTML (makes it look horrible), make a completely different (smaller, cropped) image file from the original and use it as a thumbnail (looks great but a pain in the butt to maintain two image sets) or you can use a bit of code that crops and/or shrinks it on the fly.

AspJpeg is one that we use, but that’s because we use ASP/ASP.NET on our sites. There’s lots of other options out there, for all programming languages.

In the case of AspJpeg, instead of calling the image file like this:



<img src="images/mythumb.jpg" width="100" height="200">

You call it like this:



<img src="image.asp?file=myoriginalimage.jpg&width=100&height=200">

Note that the source (src) is an ASP file not an image file. The ASP file happens to return data in an image wrapper, so the browser can display it as an image.

Along with re-scaling the original image to 100x200, I could also send more properties to image.asp that crops the picture at certain X and Y coordinates.

In the case of AspJpeg, I do believe that when you right-click and “save as” you get image.asp and you have to re-name to image.jpg to get your jpg file. It also comes down at the width and height I specified to image.asp.

Other image handlers, like the one used on the site where you downloaded your thumbnail from, might just serve up the full image when you right-click “save as” (or whatever one does on a Mac!) So you get the original image with no resizing or cropping.

The G4 incident may have worked the same way, or someone was just smart enough to view the properties of the image and find his way to the full file. In my example, you could easily see in the source that the file I was resizing is called myoriginalimage.jpg, and point your browser right to that.

Make sense?

3

Some photo software saves the thumbnail inside the larger image. The larger image may be edited while the thumbnail may stay the same. This is what happened to the TV personality. She had a photo on the web which was cropped but the thumbnail stored inside the image was of the original (nude) photo.

4

This is especially true if the software used was an “icon generator”, which will store many sizes each of which is used in a different part of your desk top, menus, etc. Some software will have a photo logo for the big desktop picture but a symbol like a simple notepad for the smaller icons.

5

I’m not sure if this is the particular nude referenced, but one of the standard images used for testing/demonstrating computer image processing is a crop of a Playboy picture of Lenna Söderberg.

6

Thanks everyone! I guess I’ll never be able to see the thumbnail any larger than a thumbnail (unless I find the photo in its original form somewhere) but I’m glad I now understand the process a bit better.

7

This is the TV personality’s story.

8

A Tin Eye search might find the original uncropped image.