enhancement: add more effects/filters (maybe code could be borrowed from this app)

[AlisterH]

Hi, this project looks great, good work! There was a similar project that never made as much progress with the drawing tools, but did have more "effects":

negative brighten (or lighten or something - I don't speak Polish, and Google translate doesn't know the word). Dim Greyscale Binarization (i.e. convert to black and white) colour intensity contrast gamma sharpen Blur

Perhaps it would be easy to borrow the code for the extra effects. http://qt-apps.org/content/show.php/Painter?content=134450

[Gr1N]

Thanks, I think we can add this effects.

[AlisterH]

Cximage could be useful too: http://www.xdp.it/cximage.htm#Features