GPU Pro 4

2. Real-Time JPEG Compression Using DirectCompute 347

float Get_YCbCr_Component_From_RGB( float3 RGB)

{

#ifdef COMPONENT_Y

return dot(RGB, float3 (0.299 ,0.587 ,0.114)) * 255.0 f;

#elif COMPONENT_CB

return dot(RGB, float3 ( -0.168736 , -0.331264 ,0.5)) * 255.0 f + 128.0 f;

#elif COMPONENT_CR

return dot(RGB, float3 (0.5 , -0.418688 , -0.081312)) * 255.0 f + 128.0 f;

#endif

}

Listing 2.4. RGB to YC

b

C

r

conversion.

ter finished execution, each group has computed one 8 × 8 block of partial JPEG

data that is later processed by the CPU. One

Dispatch method call per color

plane is invoked. All relevant shader resources are set before each invocation.

Compute color transfo ...