How to desaturate image?

[SilverWarior]

Figured it out guys. I had to use .Lock() on texture, which gave me back pointer to pixels, similar to what ScanLine does. Much faster, and with that gray multiplication trick I made it to work.

I'm glad you found solution for this.
You might wanna update the SO question with your answer so other pepole could make use of it.

[pitfiend]

Did you try http://graphics32.org/wiki/Main/Graphics32? has a lot of filters and image manipulation methods.