Shoutbox

What is wrong in doing it the correct way? (second time I'm asking this )... It looks complicated, but it realy isn't. It is as hard as your method, Millenium_edition:

To extract the data from the end of the PNG, you must know where the end is. So you need to read some data out of the PNG first to know where the end is, then extract the added stuff at the end...

In the the correct way of doing this, you need also to read some data from the PNG, but instead of skipping everything right to the end, you only skip the normal chuncks of the png, then extract your chunck in the same way as if you extracted something at the end of a file.

Creating the "special" PNG works also the same: instead of writing at the end of the file, you read some data out of the PNG, copy all the normal chuncks, and then if that is done, write your own chunks, and end the PNG...

The benefit is that it is a valid PNG. And even a bigger benefit of this all is that you can edit and change the PNG in a normal graphic editor (which must be PNG compatible of course) without loosing your "special" added chunck. (that's why I suggested a "private/ancillary/safe-to-copy" chunck)...

It indeed seems harder todo then it realy is, but that is with everything where the explaination is much more extensive then actually doing it...


EDIT: Oh btw, Millenium_edition, Welcome again at msgplus nice to see you here again