Shoutbox

Indeed nice suggestion. And that made me think "How to include data in pixels (actual imagedata) without altering the actual pixel?". Well in PNG this IS possible . But you need to know the PNG format very well for that. The trick is to use an alpha-palette.

As you know PNG's supports transparency. Normaly the pixeldata of a PNG with full transparency is stored like this: R G B A R G B A R G B A R G B A... Where RGB is the obvious red/green/blue value, and A is the transparency level. Now altering the transparency level here will result in different pixelshades, so that's no good.

But PNG also supports alpha-palette's. This means that the colors and transparency aren't stored in the pixeldata but in the palette. So, a palette is created and the pixeldata doesn't contain the R G B values but an index to the palette instead. This also means that you can have palette entries which you don't actually use in the image! And here we have our "space" to add the data Create an alpha-palette-PNG and add some extra palette entries where you will store your data.

Backdraw, I dunno if Messenger supports these PNG's, and if it does, how they are handled. But since the palette is a important part of an image, I actually have good hopes for it...

more info:
http://www.libpng.org/pub/png/

Note: but implementing this will need a great effort. You need to "read in" the PNG's (DP's) and convert them to an alpha-palette-png (<= not easy), add some palette entries and write the "new format" (including compression! etc. <= totaly not easy)...



EDIT:
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lol, this brings back memories of a big Belgian contest held back in the mid 90's. Some computer magazine (can't remember which) made a thick article spread over several issues about hidden data in normal computer files and how it can be used. They held a contest to find the hidden data in some common files, like Word docs, images, databases, etc. It opened up whole new ideas and very nice systems of hiding data. It was the hot topic to talk about in Belgian computer world lol, I remember finding some funny hidden picture of the author of the article in a ZIP file.....
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