CUDA和OpenCV实现的图像GAMMA变换

 #include
 #include
 #include
 #include
 #include "cutil_inline.h"

 #define GAMMA 0.4

 void runTest(int argc, char** argv);

 __global__ void testKernel(float* d_idata, float* d_odata, int width, int height, float gamma)
 {
  unsigned int tid_in_grid_x = blockDim.x*blockIdx.x + threadIdx.x;
  unsigned int tid_in_grid_y = blockDim.y*blockIdx.y + threadIdx.y;
  unsigned int tid_in_grid = tid_in_grid_y*width + tid_in_grid_x;

  d_odata[tid_in_grid] = powf(d_idata[tid_in_grid], gamma);
 }

 int main(int argc, char** argv)
 {
  runTest(argc, argv);
  CUT_EXIT(argc, argv);
 }

 void runTest(int argc, char** argv)
 {
  if( cutCheckCmdLineFlag(argc, (const char**)argv, "device") )     //设备初始化并设定计时器。
   cutilDeviceInit(argc, argv);
  else
   cudaSetDevice(cutGetMaxGflopsDeviceId() );

  unsigned int timer = 0;
     cutilCheckError(cutCreateTimer(&timer));
     cutilCheckError(cutStartTimer(timer));

  IplImage* pImg;
  if((pImg = cvLoadImage("lena_gray.jpg", CV_LOAD_IMAGE_GRAYSCALE)) != 0 )
     {
         cvNamedWindow("Image", 1);
         cvShowImage("Image", pImg);

   unsigned int num_blocks_x = pImg->width/16;
   unsigned int num_blocks_y = pImg->height/16;

   unsigned int mem_size = sizeof(float)*pImg->widthStep*pImg->height;

   float* h_idata = (float*)malloc(mem_size);
   float* h_odata = (float*)malloc(mem_size);

   float* d_idata;
   CUDA_SAFE_CALL(cudaMalloc((void**)&d_idata, mem_size));
   float* d_odata;
   CUDA_SAFE_CALL(cudaMalloc((void**)&d_odata, mem_size));

   for(int i = 0; i < pImg->widthStep*pImg->height; i++)  //从图像中复制数据时要特别注意变量类型，char类型的数据计算精度

  h_idata[i] = ((uchar)pImg->imageData[i])/255.0;           //太低，但是图像中只能存储char类型，所以要进行转换

   CUDA_SAFE_CALL(cudaMemcpy(d_idata, h_idata, mem_size, cudaMemcpyHostToDevice));

   dim3 grid(num_blocks_x, num_blocks_y, 1);
   dim3 threads(16, 16, 1);

   testKernel<<>>(d_idata, d_odata, pImg->width, pImg->height, GAMMA);

   CUT_CHECK_ERROR("Kernel execution failed");

   CUDA_SAFE_CALL(cudaMemcpy(h_odata, d_odata, mem_size, cudaMemcpyDeviceToHost));

   IplImage* oImg = cvCreateImage(cvSize(pImg->width,pImg->height), IPL_DEPTH_8U, 1);
   for(int i = 0; i < pImg->widthStep*pImg->height; i++)
    oImg->imageData[i] = (uchar)(int)(h_odata[i]*255);

   cvNamedWindow("Result", CV_WINDOW_AUTOSIZE);
         cvShowImage("Result", oImg);
 //  cvSaveImage("result.jpg", oImg);

   cutilCheckError( cutStopTimer( timer));
   printf( "Processing time: %f (ms)/n", cutGetTimerValue( timer));
   cutilCheckError( cutDeleteTimer( timer));

   cvWaitKey(0);
   cvDestroyWindow("Image");
         cvReleaseImage(&pImg);
   cvDestroyWindow("Result");
         cvReleaseImage(&oImg);

   free(h_idata);
   free(h_odata);
   CUDA_SAFE_CALL(cudaFree(d_idata));
   CUDA_SAFE_CALL(cudaFree(d_odata));

     }
 }