float Luminance = 0.08f;
static const float fMiddleGray = 0.18f;
static const float fWhiteCutoff = 0.8f;

//-----------------------------------------------------------------------------
// Pixel Shader: BrightPassFilter
// Desc: Perform a high-pass filter on the source texture
//-----------------------------------------------------------------------------
float4 BrightPassFilter( in float2 Tex : TEXCOORD0 ) : COLOR0
{
    float3 ColorOut = tex2D( g_samSrcColor, Tex );

    ColorOut *= fMiddleGray / ( Luminance + 0.001f );
    ColorOut *= ( 1.0f + ( ColorOut / ( fWhiteCutoff * fWhiteCutoff ) ) );
    ColorOut -= 5.0f;

    ColorOut = max( ColorOut, 0.0f );

    ColorOut /= ( 10.0f + ColorOut );

    return float4( ColorOut, 1.0f );
}