das hier:
float fContrast = 1.02;

texture TargetMap;
sampler TargetSampler = sampler_state { texture = <TargetMap>; };

float4 postprocessing_contrast( float2 Tex : TEXCOORD0 ) : COLOR0
{
float4 Color = float4(0, 0, 0, 1.0);
float4 Color1 = float4(0.5, 0.5, 0.5, 1.0);
Color = ((tex2D( TargetSampler, Tex.xy) - Color1) * fContrast) + Color1 * 0.95;
return Color;
}

technique Contrast
{
pass p1
{
PixelShader = compile ps_2_0 postprocessing_contrast();
}
}

an alle: druckwelle nich vergessen