Pixel level operations

I would like play with custom 2d effects and small filters apps, not for games. Is it possible in construct? Things like: for each pixel do, get color, do calculations, set a color.

How can I get an RGB color from a specific pixel?

Any advice is wellcome

The best way to do this is by writing a custom pixel shader effect, because these run really quickly on the graphics card. See Pixel Shaders.

So there's no way to get the color of a pixel otherwise? I'm making a paint program, and it would be handy.

Any recommended site to learn about pixel shader?

Any recommended site to learn about pixel shader?

I learnt the basics from this site http://www.facewound.com/tutorials/shader1/

But you'll want to take a look at some of the existing .FX files in the construct/effects folder to get an idea of how they're laid out for Construct's specific use.

Aye, anything intensive (what size images are these?) should be offloaded off processors. Graphics cards are more efficient at these sort of things. Although, I have no clue as to how fast it will perform on integrated VS a modern processor; especialy if you're on vista, which LOVES to throttle the hell out of integrated GPU's unless you know how to set it up.

Thanks for the responses. BenH, thanks for the link. I have been searching at Google but i have founded only very technical stuff. This seams to be more "readable" . I'm learning from Construct's fx files too.