OpenCL study - code03 rgb2gray

记录一下学习OpenCL的过程，下面更新关于rgb转换为gray的操作，需要OpenCL以及OpenCV

// grayscale.cl__kernel void rgb_to_gray(__global const uchar* rgb_image, __global uchar* gray_image, const int width, const int height){ int x = get_global_id(0); int y = get_global_id(1); int idx = y * width + x; if (x < width && y < height) { int rgb_index = idx * 3; uchar r = rgb_image[rgb_index + 0]; uchar g = rgb_image[rgb_index + 1]; uchar b = rgb_image[rgb_index + 2]; uchar gray = (uchar)(0.299f * r + 0.587f * g + 0.114f * b); gray_image[idx] = gray; }}

//// Created by zixhu on 2025/7/26.//#ifndef COMPUTERVISION_RGBMAIN_H#define COMPUTERVISION_RGBMAIN_H#include #include \"../helper/opencl_helper.h\"int runRgb2gray() { // 1. 读取图像（BGR） cv::Mat img = cv::imread(\"../src/opencl/sources/img.png\"); if (img.empty()) { printf(\"Failed to load image.\\n\"); return -1; } // 2. 转成 RGB（因为 OpenCL kernel 假设的是 RGB） cv::cvtColor(img, img, cv::COLOR_BGR2RGB); int width = img.cols; int height = img.rows; int size_rgb = width * height * 3; int size_gray = width * height; // 3. 初始化输出灰度图内存 std::vector<uchar> gray_data(size_gray); // 4. 初始化 OpenCL OpenCLObjects ocl = init_opencl(\"grayscale.cl\", \"rgb_to_gray\"); cl_int err; // 5. 创建缓冲区 cl_mem input_buf = clCreateBuffer(ocl.context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, size_rgb * sizeof(uchar), img.data, &err); CHECK_ERROR(err, \"clCreateBuffer input\"); cl_mem output_buf = clCreateBuffer(ocl.context, CL_MEM_WRITE_ONLY,  size_gray * sizeof(uchar), NULL, &err); CHECK_ERROR(err, \"clCreateBuffer output\"); // 6. 设置 kernel 参数 clSetKernelArg(ocl.kernel, 0, sizeof(cl_mem), &input_buf); clSetKernelArg(ocl.kernel, 1, sizeof(cl_mem), &output_buf); clSetKernelArg(ocl.kernel, 2, sizeof(int), &width); clSetKernelArg(ocl.kernel, 3, sizeof(int), &height); // 7. 启动 kernel size_t global_size[2] = { (size_t)width, (size_t)height }; err = clEnqueueNDRangeKernel(ocl.queue, ocl.kernel, 2, NULL, global_size, NULL, 0, NULL, NULL); CHECK_ERROR(err, \"clEnqueueNDRangeKernel\"); clFinish(ocl.queue); // 8. 拷贝结果回主机 err = clEnqueueReadBuffer(ocl.queue, output_buf, CL_TRUE, 0, size_gray * sizeof(uchar), gray_data.data(), 0, NULL, NULL); CHECK_ERROR(err, \"clEnqueueReadBuffer\"); // 9. 构造灰度图并显示 cv::Mat gray_img(height, width, CV_8UC1, gray_data.data()); cv::imshow(\"Gray Image\", gray_img); cv::waitKey(0); // 10. 清理 clReleaseMemObject(input_buf); clReleaseMemObject(output_buf); release_opencl(&ocl); return 0;}#endif //COMPUTERVISION_RGBMAIN_H

//// Created by zixhu on 2025/7/26.//#ifndef COMPUTERVISION_OPENCL_HELPER_H#define COMPUTERVISION_OPENCL_HELPER_H#include #include #include #include #define CHECK_ERROR(err, msg) \\ if (err != CL_SUCCESS) { \\ fprintf(stderr, \"%s failed with error %d\\n\", msg, err); \\ exit(1); \\ }typedef struct { cl_platform_id platform; cl_device_id device; cl_context context; cl_command_queue queue; cl_program program; cl_kernel kernel;} OpenCLObjects;// 加载内核源码char *read_source(const char *filename) { FILE *fp = fopen(filename, \"r\"); if (!fp) { perror(\"Failed to open kernel file\"); exit(1); } fseek(fp, 0, SEEK_END); size_t size = ftell(fp); rewind(fp); char *source = (char *)malloc(size + 1); fread(source, 1, size, fp); source[size] = \'\\0\'; fclose(fp); return source;}// 初始化 OpenCL，并构建 kernelOpenCLObjects init_opencl(const char *source_file, const char *kernel_name) { OpenCLObjects ocl; cl_int err; err = clGetPlatformIDs(1, &ocl.platform, NULL); CHECK_ERROR(err, \"clGetPlatformIDs\"); err = clGetDeviceIDs(ocl.platform, CL_DEVICE_TYPE_DEFAULT, 1, &ocl.device, NULL); CHECK_ERROR(err, \"clGetDeviceIDs\"); ocl.context = clCreateContext(NULL, 1, &ocl.device, NULL, NULL, &err); CHECK_ERROR(err, \"clCreateContext\"); ocl.queue = clCreateCommandQueue(ocl.context, ocl.device, 0, &err); CHECK_ERROR(err, \"clCreateCommandQueue\"); char *source = read_source(source_file); ocl.program = clCreateProgramWithSource(ocl.context, 1, (const char **)&source, NULL, &err); CHECK_ERROR(err, \"clCreateProgramWithSource\"); err = clBuildProgram(ocl.program, 1, &ocl.device, NULL, NULL, NULL); if (err != CL_SUCCESS) { char log[4096]; clGetProgramBuildInfo(ocl.program, ocl.device, CL_PROGRAM_BUILD_LOG, sizeof(log), log, NULL); fprintf(stderr, \"Build Error:\\n%s\\n\", log); exit(1); } ocl.kernel = clCreateKernel(ocl.program, kernel_name, &err); CHECK_ERROR(err, \"clCreateKernel\"); free(source); return ocl;}void release_opencl(OpenCLObjects *ocl) { clReleaseKernel(ocl->kernel); clReleaseProgram(ocl->program); clReleaseCommandQueue(ocl->queue); clReleaseContext(ocl->context);}#endif //COMPUTERVISION_OPENCL_HELPER_H