     cuda_ret = cudaDeviceSynchronize();
     if(cuda_ret != cudaSuccess)
       {
-      //  printf("%s\n", cudaGetErrorString(cuda_ret));
+        printf("%s\n", cudaGetErrorString(cuda_ret));
       }
     cudaMemcpy(b_dev, b, size * sizeof(float), cudaMemcpyHostToDevice);
 
     cuda_ret = cudaDeviceSynchronize();
     if(cuda_ret != cudaSuccess)
       {
-      //  printf("%s\n", cudaGetErrorString(cuda_ret));
+          printf("%s\n", cudaGetErrorString(cuda_ret));
       }
 
     dim3 dim_grid_gray(width / 16 + 1, height / 16 + 1, 1);

	cuda_ret = cudaDeviceSynchronize();
	if(cuda_ret != cudaSuccess)
    {
        //printf("%s\n", cudaGetErrorString(cuda_ret));
    }
    cudaFree(r_dev);
    cudaFree(g_dev);

	cuda_ret = cudaDeviceSynchronize();
	if(cuda_ret != cudaSuccess)
    {
        printf("%s\n", cudaGetErrorString(cuda_ret));
    }

    cudaFree(grayscale_dev);
