Make photos flat.

[OldSchool98]

So i have to use a program that has correct pincushion / barrel distortion function to make the photo looks like the one some user fixed on the first page on this thread.

 

[TWX]

So i have to use a program that has correct pincushion / barrel distortion function to make the photo looks like the one some user fixed on the first page on this thread.

I believe that you can do this kind of edit in GNU Image Manipulation Program, or GIMP, which is open-source and thus free. There will be various transformation options. It probably will be a bit harder to do than in Photoshop, but free's free.