This example shows you how to use HLSL(High level sheder language) in your XNA game.
HLSL is a sheding language developed by Microsoft.
And from that language you can direcly talk to the GPU.
This have three main forms vertex sheder,pixel sheder and geometry sheder.
This example is using pixel shader to process a 2d image.
Press W or Q to see the effect.
you can download the source code from-