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This image: http://allspark.net/cypherswipe/Pumpkin.BMP just shows a message saying that it can only be used in the holiday lights program whenever it's viewed in an image viewer or browser, yet displays this: http://allspark.net/cypherswipe/pumpkin.png when viewed in holiday lights. If I were viewing the image from a website, I would assume there was some server side script protecting it. If it wouldn't open at all in an image viewer, I would assume it was actually some other, proprietary format that happened to have the same extension. If it was almost any image format other than BMP, I might think it had some method of protection available that I was unaware of. BMP however is an extremely basic format, I didn't think it was technically possible togive it any form of protection or encryption like this. I thought BMPs could only display single layer, still images. (Even "animated" BMPs are actually just filmstrip type images, it's the viewing prog that "animates" them.)

So, does anyone have any idea how in the world this was done? I don't give a crap about the image itself, it's a simple clipart type pic, plus (if I did want it) I can get it very easily by simply taking a screenshot while the prog is running (which is how I got the PNG version I posted), but I'm really curious as to how they did it.
 

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I checked it out, it's just two pictures in one file following eachother. If you use a hex editor like hex workshop and cut away from the start of the file to just before the second BM identifier, then save the file and open it, the pumpkin will show.

Edit: I wrote a quick tool that can decode them, source code, .exe and an example picture included.

Edit2:
Uploaded new version, you can both decode and combine (hide the second) pictures with this version, you get to select when starting it.

Edit3, get the new version 2.1 here:
http://www.lentoman.net/tools.php

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GetSecondPicture V2.1

Author: Lennart "LentoMan" Johannesson
Web: www.lentoman.net
E-Mail: <removed by me to prevent spam>

What's this?
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Cypherswipe on the NGEmu forum wanted to know how the holiday lights program
could hide a second picture inside a bmp.

I decided to look at the file in a hex editor, a minute later I started working
on this program. It will let you hide a bmp picture in another or extract
the hidden one. Nothing is encrypted though so be careful.

Sources included.


Usage
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Combine will let your choose two input bmp files and a save filename.
The second picture will be "hidden" after the first bmp.

Get 2nd will let you select a combined bmp and extract the second
hidden picture to a specified destination.


Version history
---------------

2.1 *Minor code cleanups
*Added readme.txt
*Added "file successfully saved" messagebox after combine is complete

2.0 Added Combine option

1.0 First Release
 
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