4、host端程序代碼
Host端程序處理流程就是按照前面“程序設計”一節編寫的。除了調用OpenCL+OpenCV的API函數，其他的地方都是按照C/C++語法編寫的。
具體代碼如下：
1. // ImageRotate.cpp : 定義控制檯應用程序的入口點。
2. //
3.
4. #include "stdafx.h"
5. #include <iostream>
6. #include <fstream>
7. #include <sstream>
8.
9. #include <opencv2/opencv.hpp>
10.
11. #ifdef __APPLE__
12. #include <OpenCL/cl.h>
13. #else
14. #include <CL/cl.h>
15. #endif
16.
17. using namespace cv;
18.
19. int _tmain(int argc, _TCHAR* argv[])
20. {
21. cl_int ciErrNum;
22. const char *fileName = "ImageRotate.cl";
23. int width = 0, height = 0;
24. float cos_theta = 0.7071067811865476, sin_theta = 0.7071067811865475; //for degree 45
25. //float cos_theta = 0.5, sin_theta = 0.5;
26. const char* imageName = "F:\\code\\pic\\test01.jpg";
27. char *bufInput = NULL, *bufOutput = NULL;
28.
29.
30. //read one jpeg pic and store it in a Mat variable.
31. Mat img = imread(imageName);
32. if (!img.data) {
33. std::cout << "fail to open the file:" << imageName << std::endl;
34. }
35.
36. //the type of img is RGB, convert to gray image.
37. Mat imgGray;
38. cvtColor(img, imgGray, CV_BGR2GRAY);
39. width = imgGray.cols;
40. height = imgGray.rows;
41. std::cout << "picture width: " << width << ", height: " << height << std::endl;
42.
43. //save the source data of original gray image.
44. FILE *yuvFileOrg = NULL;
45. fopen_s(&yuvFileOrg, "gray_org.yuv", "wb");
46. fwrite(imgGray.data, width * height * sizeof(unsigned char), 1, yuvFileOrg);
47. fclose(yuvFileOrg);
48. yuvFileOrg = NULL;
49.
50. //display the original gray image in a window.
51. namedWindow( imageName, CV_WINDOW_AUTOSIZE );
52. imshow(imageName, imgGray);
53. //waitKey(0);
54.
55. //allocate the input buffer to store the original gray image
56. if (NULL == (bufInput = (char *)malloc(width * height * sizeof(char)))) {
57. std::cerr << "Failed to malloc buffer for input image. " << std::endl;
58. return NULL;
59. }
60.
61. //allocate the output buffer to store the image rotated.
62. if (NULL == (bufOutput = (char *)malloc(width * height * sizeof(char)))) {
63. std::cerr << "Failed to malloc buffer for output image. " << std::endl;
64. return NULL;
65. }
66.
67. //copy the data of gray image to the input buffer. initialize the output buffer by zero.
68. memcpy(bufInput, imgGray.data, width * height * sizeof(unsigned char));
69. memset(bufOutput, 0, width * height * sizeof(unsigned char));
70.
71. //use the first platform
72. cl_platform_id platform;
73. ciErrNum = clGetPlatformIDs(1, &platform, NULL);
74.
75. //use the first device
76. cl_device_id device;
77. ciErrNum = clGetDeviceIDs(
78. platform,
79. CL_DEVICE_TYPE_ALL,
80. 1,
81. &device,
82. NULL);
83.
84. cl_context_properties cps[3] = {
85. CL_CONTEXT_PLATFORM, (cl_context_properties)platform, 0
86. };
87. //create the context
88. cl_context ctx = clCreateContext(
89. cps,
90. 1,
91. &device,
92. NULL,
93. NULL,
94. &ciErrNum);
95.
96. //create the command queue
97. cl_command_queue myqueue = clCreateCommandQueue(
98. ctx,
99. device,
100. 0,
101. &ciErrNum);
102.
103. //allocate space for original image on the device
104. cl_mem bufferA = clCreateBuffer(
105. ctx,
106. CL_MEM_READ_ONLY,
107. width * height * sizeof(unsigned char),
108. NULL,
109. &ciErrNum);
110. //copy input buffer to the device
111. ciErrNum = clEnqueueWriteBuffer(
112. myqueue,
113. bufferA,
114. CL_TRUE,
115. 0,
116. width * height * sizeof(unsigned char),
117. (void *)bufInput,
118. 0,
119. NULL,
120. NULL);
121.
122. //allocate space for rotated image on the device
123. cl_mem bufferC = clCreateBuffer(
124. ctx,
125. CL_MEM_READ_WRITE,
126. width * height * sizeof(unsigned char),
127. NULL,
128. &ciErrNum);
129.
130. //open kernel file and read the content to a string variable.
131. std::ifstream kernelFile("ImageRotate.cl", std::ios::in);
132. if (!kernelFile.is_open()) {
133. std::cerr << "Failed to open file for reading: " << fileName << std::endl;
134. return NULL;
135. }
136. std::ostringstream oss;
137. oss << kernelFile.rdbuf();
138. std::string srcStdStr = oss.str();
139. const char *srcStr = srcStdStr.c_str();
140. kernelFile.close();
141.
142. //create the program with source code of kernel.
143. cl_program myprog = clCreateProgramWithSource(
144. ctx,
145. 1,
146. (const char**)&srcStr,
147. NULL,
148. &ciErrNum);
149.
150. //compile the program. passing NULL for the 'device_list' argument targets all devices in the context
151. ciErrNum = clBuildProgram(myprog, 0, NULL, NULL, NULL, NULL);
152.
153. //create the kernel
154. cl_kernel mykernel = clCreateKernel(
155. myprog,
156. "img_rotate",
157. &ciErrNum);
158.
159. //set the kernel arguments
160. clSetKernelArg(mykernel, 0, sizeof(cl_mem), (void *)&bufferC);
161. clSetKernelArg(mykernel, 1, sizeof(cl_mem), (void *)&bufferA);
162. clSetKernelArg(mykernel, 2, sizeof(cl_int), (void *)&width);
163. clSetKernelArg(mykernel, 3, sizeof(cl_int), (void *)&height);
164. clSetKernelArg(mykernel, 4, sizeof(cl_float), (void *)&cos_theta);
165. clSetKernelArg(mykernel, 5, sizeof(cl_float), (void *)&sin_theta);
166.
167. //set local and global workgroup sizes
168. size_t localws[2] = {1, 1};
169. size_t globalws[2] = {width, height};
170.
171. //execute the kernel
172. ciErrNum = clEnqueueNDRangeKernel(
173. myqueue,
174. mykernel,
175. 2,
176. NULL,
177. globalws,
178. localws,
179. 0,
180. NULL,
181. NULL);
182.
183. //read the output data back to the host
184. ciErrNum = clEnqueueReadBuffer(
185. myqueue,
186. bufferC,
187. CL_TRUE,
188. 0,
189. width * height * sizeof(unsigned char),
190. bufOutput,
191. 0,
192. NULL,
193. NULL);
194.
195. //copy the output data from output buffer to Mat variable.
196. memcpy(imgGray.data, bufOutput, width * height * sizeof(unsigned char));
197.
198. //save the source data for gray image rotated
199. FILE *yuvFile = NULL;
200. fopen_s(&yuvFile, "gray.yuv", "wb");
201. fwrite(imgGray.data, width * height * sizeof(unsigned char), 1, yuvFile);
202. fclose(yuvFile);
203. yuvFile = NULL;
204.
205. //save the gray image rotated.
206. imwrite("test_gray.jpg", imgGray);
207.
208. //show the gray image rotated.
209. const char *winName = "gray_image_rotated";
210. namedWindow(winName, CV_WINDOW_AUTOSIZE );
211. imshow(winName, imgGray);
212. waitKey(0);
213. destroyAllWindows();
214.
215. //release all resource
216. if (bufInput != NULL)
217. free(bufInput);
218.
219. if (bufOutput != NULL)
220. free(bufOutput);
221.
222. if (bufferA != 0)
223. clReleaseMemObject(bufferA);
224.
225. if (bufferC != 0)
226. clReleaseMemObject(bufferC);
227.
228. if (myqueue != 0)
229. clReleaseCommandQueue(myqueue);
230.
231. if (mykernel != 0)
232. clReleaseKernel(mykernel);
233.
234. if (myprog != 0)
235. clReleaseProgram(myprog);
236.
237. if (ctx != 0)
238. clReleaseContext(ctx);
239.
240. return 0;
241. }
5、程序處理結果
原始的灰度圖像如下所示：
經過45度旋轉的圖像如下：
將sin、cos值都設置爲0.5時的處理結果如下：
經過45度旋轉的圖像上面有很多暗點，那些暗點是在設備端分配的buffer中原始的點。意味着那些區域並非每個點都有對應的點旋轉過來。
在kernel程序中計算座標點時，使用的是float類型，最後獲取圖像時是將float轉換爲int了。應該是因爲精度損失導致某些座標點上沒有對應的像素點，所以保留了buffer中原有的數據。
而當sin、cos設置爲0.5時，圖像看着就沒有暗紋。按照0.5計算很少有精度的損失，所以就不存在上面的問題。
是因爲旋轉算法精度不夠，還是程序哪裏實現錯了，這是個問題，將在後面的學習中去尋找問題的答案。
（完）
