colored image to greyscale image using CUDA parallel processing

Question

I am trying to solve a problem in which i am supposed to change a colour image to a greyscale image. For this purpose i am using CUDA parallel approach.

The kerne code i

Answer 1

Now, since I posted this question I have been continuously working on this problem
there are a couple of improvements that should be done in order to get this problem correct now I realize my initial solution was wrong .
Changes to be done:-

 1. absolute_position_x =(blockIdx.x * blockDim.x) + threadIdx.x;
 2. absolute_position_y = (blockIdx.y * blockDim.y) + threadIdx.y;

Secondly,

 1. const dim3 blockSize(24, 24, 1);
 2. const dim3 gridSize((numCols/16), (numRows/16) , 1);

In the solution we are using a grid of numCols/16 * numCols/16
and blocksize of 24 * 24

code executed in 0.040576 ms

@datenwolf : thanks for answering above!!!