opencv 2 computer vision application programming第四章翻译

有点晚了先开个头，明天翻译具体内容

第四章 用直方图统计像素
这一章包括:
计算图像的直方图
应用查表以修改图像外观
补偿图像直方图
幕后使用直方图以检测特定的图像内容
使用平均移动算法以找到物体
使用直方图比较以恢复相似图像

计算灰度图像的直方图，并用图显示出来：

 1 #include <cv.h>
 2 #include <highgui.h>
 3
 4 using namespace std;
 5 using namespace cv;
 6
 7 class Histogram1D{
 8 private:
 9     int histSize[1];
10     float hranges[2];
11     const float* ranges[1];
12     int channels[1];
13 public:
14     Histogram1D(){
15         histSize[0]=256;
16         hranges[0]=0.0;
17         hranges[1]=255.0;
18         ranges[0]=hranges;
19         channels[0]=0;
20     }
21
22     MatND getHistogram(const Mat& image){
23         MatND hist;
24         calcHist(&image, 1, channels, Mat(), hist, 1,
25                  histSize, ranges);
26         return hist;
27     }
28     Mat getHistogramImage(const Mat& image){
29         MatND hist=getHistogram(image);
30         double maxVal=0;
31         double minVal=0;
32         minMaxLoc(hist, &minVal, &maxVal, 0, 0);
33         Mat histImg(histSize[0], histSize[0], CV_8U, Scalar(255));
34         int hpt=static_cast<int>(0.9*histSize[0]);
35         for(int h=0; h<histSize[0]; h++){
36             float binVal=hist.at<float>(h);
37             int intensity=static_cast<int>(binVal*hpt/maxVal);
38             line(histImg, Point(h, histSize[0]), Point(h, histSize[0]-intensity),Scalar::all(0));
39         }
40         return histImg;
41     }
42 };
43
44
45
46 int main(){
47     Mat image=imread("C:/testdir/barcode.bmp");
48     Histogram1D h;
49     MatND histo=h.getHistogram(image);
50 /*    for(int i=0; i<256; i++){
51         cout << "Value " << i << "=" <<
52                 histo.at<float>(i) << endl;
53     }
54     */
55     namedWindow("Histogram");
56     imshow("Histogram", h.getHistogramImage(image));
57     waitKey(0);
58 }

 threshold是边缘检测函数，例如可以这样应用

 1 #include <cv.h>
 2 #include <highgui.h>
 3
 4 using namespace std;
 5 using namespace cv;
 6
 7 class Histogram1D{
 8 private:
 9     int histSize[1];
10     float hranges[2];
11     const float* ranges[1];
12     int channels[1];
13 public:
14     Histogram1D(){
15         histSize[0]=256;
16         hranges[0]=0.0;
17         hranges[1]=255.0;
18         ranges[0]=hranges;
19         channels[0]=0;
20     }
21
22     MatND getHistogram(const Mat& image){
23         MatND hist;
24         calcHist(&image, 1, channels, Mat(), hist, 1,
25                  histSize, ranges);
26         return hist;
27     }
28     Mat getHistogramImage(const Mat& image){
29         MatND hist=getHistogram(image);
30         double maxVal=0;
31         double minVal=0;
32         minMaxLoc(hist, &minVal, &maxVal, 0, 0);
33         Mat histImg(histSize[0], histSize[0], CV_8U, Scalar(255));
34         int hpt=static_cast<int>(0.9*histSize[0]);
35         for(int h=0; h<histSize[0]; h++){
36             float binVal=hist.at<float>(h);
37             int intensity=static_cast<int>(binVal*hpt/maxVal);
38             line(histImg, Point(h, histSize[0]), Point(h, histSize[0]-intensity),Scalar::all(0));
39         }
40         return histImg;
41     }
42 };
43
44
45
46 int main(){
47     Mat image=imread("C:/testdir/Koala.jpg");
48 //    Mat image=imread("C:/testdir/barcode.bmp");
49     Histogram1D h;
50     Mat thresholded;
51     threshold(image, thresholded, 60, 255, THRESH_BINARY);
52     MatND histo=h.getHistogram(image);
53 /*    for(int i=0; i<256; i++){
54         cout << "Value " << i << "=" <<
55                 histo.at<float>(i) << endl;
56     }
57     */
58     namedWindow("Histogram");
59     imshow("Image", thresholded);
60     imshow("Histogram", h.getHistogramImage(image));
61     waitKey(0);
62 }

使用equalizeHist函数的时候报错，google之后发现要求图片格式应该为CV_8UC1才可以用的，所以平凡图像需要先转化咯：

 1 #include <cv.h>
 2 #include <highgui.h>
 3
 4 using namespace std;
 5 using namespace cv;
 6
 7 Mat equalize(const Mat& image){
 8     Mat result(image);
 9     equalizeHist(image, result);
10     return result;
11 }
12
13 int main(){
14     char* name="C:/testdir/Koala.jpg";
15     IplImage *img = cvLoadImage( name, CV_LOAD_IMAGE_GRAYSCALE );
16     Mat src( img, 0 );
17     src = Mat_<float>( src );
18     Mat dst = Mat::zeros( src.rows, src.cols, src.type() );
19     src = Mat_<uchar>(src);
20     equalizeHist( src, dst );
21     imshow("dst", src);
22     waitKey(0);
23     return 0;
24 }