1 #include <stdio.h> 2 #include <iostream> 3 #include <opencv2/imgproc/imgproc.hpp> 4 #include <opencv2/highgui/highgui.hpp> 5 #include <opencv2/core/utility.hpp> 6 7 using namespace cv; // all the new API is put into "cv" namespace. Export its content 8 using namespace std; 9 10 static void help() 11 { 12 cout << 13 "\nThis program shows how to use cv::Mat and IplImages converting back and forth.\n" 14 "It shows reading of images, converting to planes and merging back, color conversion\n" 15 "and also iterating through pixels.\n" 16 "Call:\n" 17 "./image [image-name Default: ../data/lena.jpg]\n" << endl; 18 } 19 20 // enable/disable use of mixed API in the code below. 21 #define DEMO_MIXED_API_USE 1 22 23 #ifdef DEMO_MIXED_API_USE 24 # include <opencv2/highgui/highgui_c.h> 25 # include <opencv2/imgcodecs/imgcodecs_c.h> 26 #endif 27 28 int main( int argc, char** argv ) 29 { 30 help(); 31 const char* imagename = argc > 1 ? argv[1] : "../data/lena.jpg"; 32 #if DEMO_MIXED_API_USE 33 //! [iplimage] 34 Ptr<IplImage> iplimg(cvLoadImage(imagename)); // Ptr<T> is safe ref-counting pointer class 35 if(!iplimg) 36 { 37 fprintf(stderr, "Can not load image %s\n", imagename); 38 return -1; 39 } 40 Mat img = cv::cvarrToMat(iplimg); // cv::Mat replaces the CvMat and IplImage, but it's easy to convert 41 // between the old and the new data structures (by default, only the header 42 // is converted, while the data is shared) 43 //! [iplimage] 44 #else 45 Mat img = imread(imagename); // the newer cvLoadImage alternative, MATLAB-style function 46 if(img.empty()) 47 { 48 fprintf(stderr, "Can not load image %s\n", imagename); 49 return -1; 50 } 51 #endif 52 53 if( img.empty() ) // check if the image has been loaded properly 54 return -1; 55 56 Mat img_yuv; 57 cvtColor(img, img_yuv, COLOR_BGR2YCrCb); // convert image to YUV color space. The output image will be created automatically 58 59 vector<Mat> planes; // Vector is template vector class, similar to STL's vector. It can store matrices too. 60 split(img_yuv, planes); // split the image into separate color planes 61 62 #if 1 63 // method 1. process Y plane using an iterator 64 MatIterator_<uchar> it = planes[0].begin<uchar>(), it_end = planes[0].end<uchar>(); 65 for(; it != it_end; ++it) 66 { 67 double v = *it*1.7 + rand()%21-10; 68 *it = saturate_cast<uchar>(v*v/255.); 69 } 70 71 // method 2. process the first chroma plane using pre-stored row pointer. 72 // method 3. process the second chroma plane using individual element access 73 for( int y = 0; y < img_yuv.rows; y++ ) 74 { 75 uchar* Uptr = planes[1].ptr<uchar>(y); 76 for( int x = 0; x < img_yuv.cols; x++ ) 77 { 78 Uptr[x] = saturate_cast<uchar>((Uptr[x]-128)/2 + 128); 79 uchar& Vxy = planes[2].at<uchar>(y, x); 80 Vxy = saturate_cast<uchar>((Vxy-128)/2 + 128); 81 } 82 } 83 84 #else 85 Mat noise(img.size(), CV_8U); // another Mat constructor; allocates a matrix of the specified size and type 86 randn(noise, Scalar::all(128), Scalar::all(20)); // fills the matrix with normally distributed random values; 87 // there is also randu() for uniformly distributed random number generation 88 GaussianBlur(noise, noise, Size(3, 3), 0.5, 0.5); // blur the noise a bit, kernel size is 3x3 and both sigma's are set to 0.5 89 90 const double brightness_gain = 0; 91 const double contrast_gain = 1.7; 92 #if DEMO_MIXED_API_USE 93 // it's easy to pass the new matrices to the functions that only work with IplImage or CvMat: 94 // step 1) - convert the headers, data will not be copied 95 IplImage cv_planes_0 = planes[0], cv_noise = noise; 96 // step 2) call the function; do not forget unary "&" to form pointers 97 cvAddWeighted(&cv_planes_0, contrast_gain, &cv_noise, 1, -128 + brightness_gain, &cv_planes_0); 98 #else 99 addWeighted(planes[0], contrast_gain, noise, 1, -128 + brightness_gain, planes[0]); 100 #endif 101 const double color_scale = 0.5; 102 // Mat::convertTo() replaces cvConvertScale. One must explicitly specify the output matrix type (we keep it intact - planes[1].type()) 103 planes[1].convertTo(planes[1], planes[1].type(), color_scale, 128*(1-color_scale)); 104 // alternative form of cv::convertScale if we know the datatype at compile time ("uchar" here). 105 // This expression will not create any temporary arrays and should be almost as fast as the above variant 106 planes[2] = Mat_<uchar>(planes[2]*color_scale + 128*(1-color_scale)); 107 108 // Mat::mul replaces cvMul(). Again, no temporary arrays are created in case of simple expressions. 109 planes[0] = planes[0].mul(planes[0], 1./255); 110 #endif 111 112 // now merge the results back 113 merge(planes, img_yuv); 114 // and produce the output RGB image 115 cvtColor(img_yuv, img, COLOR_YCrCb2BGR); 116 117 // this is counterpart for cvNamedWindow 118 namedWindow("image with grain", WINDOW_AUTOSIZE); 119 #if DEMO_MIXED_API_USE 120 // this is to demonstrate that img and iplimg really share the data - the result of the above 121 // processing is stored in img and thus in iplimg too. 122 cvShowImage("image with grain", iplimg); 123 #else 124 imshow("image with grain", img); 125 #endif 126 waitKey(); 127 128 return 0; 129 // all the memory will automatically be released by Vector<>, Mat and Ptr<> destructors. 130 } 131
