1 #include <iostream>
 2 #include <opencv2/opencv.hpp>
 3 #include "opencv2/highgui/highgui.hpp"
 4 #include "opencv2/imgproc/imgproc.hpp"
 5
 6 int main(int argc, char **argv) {
 7     cv::Mat src = cv::imread("/home/cv/Downloads/images/P1180141.JPG", 1);
 8     cv::resize(src, src, cv::Size(src.cols / 3, src.rows / 3), cv::INTER_CUBIC);
 9     cv::imshow("original_after_resize", src);
10
11     // blue channel
12     cv::Mat mytemp1(src.rows, src.cols, CV_8UC3, cv::Scalar(255, 0, 0));
13     cv::imshow("temp test", mytemp1);
14     // green channel
15     cv::Mat mytemp2(src.rows, src.cols, CV_8UC3, cv::Scalar(0, 255, 0));
16     cv::imshow("temp test", mytemp2);
17     // red channel
18     cv::Mat mytemp3(src.rows, src.cols, CV_8UC3, cv::Scalar(0, 0, 255));
19     cv::imshow("temp test", mytemp3);
20     cv::waitKey(0);
21     return 0;
22 }

 1 #include <opencv2/opencv.hpp>
 2 #include "opencv2/highgui/highgui.hpp"
 3 #include "opencv2/imgproc/imgproc.hpp"
 4
 5 int main(int argc, char **argv) {
 6     cv::Mat src = cv::imread("/home/cv/Downloads/images/P1180141.JPG", 1);
 7     cv::resize(src, src, cv::Size(src.cols / 3, src.rows / 3), cv::INTER_CUBIC);
 8     for (int i = 0; i < 3; i++) {
 9         cv::Mat temp_bgr(src.rows, src.cols, CV_8UC3, cv::Scalar(0, 0, 0));
10         cv::Mat temp(src.rows, src.cols, CV_8UC1);
11         cv::Mat out[] = {temp_bgr};
12         int from_to[] = {i, i};
13         cv::mixChannels(&src, 1, out, 1, from_to, 1);
14         cv::imshow("single channel", temp_bgr);
15         cv::waitKey(0);
16     }
17
18     return 0;
19 }

 1 #include <iostream>
 2 #include <opencv2/opencv.hpp>
 3 #include "opencv2/highgui/highgui.hpp"
 4 #include "opencv2/imgproc/imgproc.hpp"
 5
 6 int main(int argc, char **argv) {
 7     cv::Mat src = cv::imread("/home/cv/Downloads/images/P1180141.JPG", 1);
 8     cv::resize(src, src, cv::Size(src.cols / 3, src.rows / 3), cv::INTER_CUBIC);
 9     cv::imshow("original_after_resize", src);
10
11     cv::Mat img_hsv;
12     cv::cvtColor(src, img_hsv, CV_BGR2HSV);
13     cv::Mat dst;
14     dst.create(img_hsv.size(), img_hsv.depth());
15
16     int ch[] = {0, 0};
17     int ch1[] = {1, 0};
18     int ch2[] = {2, 0};
19
20     // Hue 色调通道
21     cv::mixChannels(&img_hsv, 1, &dst, 1, ch, 1);
22     cv::imshow("hsv-h", dst);
23     // Saturation 饱和度通道
24     cv::mixChannels(&img_hsv, 1, &dst, 1, ch1, 1);
25     cv::imshow("hsv-s", dst);
26     // Lightness/Value 亮度/像素值通道
27     cv::mixChannels(&img_hsv, 1, &dst, 1, ch2, 1);
28     cv::imshow("hsv-v", dst);
29     cv::waitKey(0);
30
31     return 0;
32 }

 1 #include <iostream>
 2 #include <vector>
 3 #include <opencv2/opencv.hpp>
 4 #include "opencv2/highgui/highgui.hpp"
 5 #include "opencv2/imgproc/imgproc.hpp"
 6
 7 int main(int argc, char **argv) {
 8     cv::Mat src = cv::imread("/home/cv/Downloads/images/P1180141.JPG", 1);
 9     cv::resize(src, src, cv::Size(src.cols / 3, src.rows / 3), cv::INTER_CUBIC);
10     cv::imshow("original_after_resize", src);
11
12     // YUV color space
13     cv::Mat img_yuv;
14     cv::cvtColor(src, img_yuv, CV_BGR2YUV);
15     cv::Mat dst;
16     dst.create(img_yuv.size(), img_yuv.depth());
17
18     // Luminance, 明亮度，灰度值
19     int ch[] = {0, 0};
20     cv::mixChannels(&img_yuv, 1, &dst, 1, ch, 1);
21     cv::imshow("yuv-y", dst);
22     // Chrominance, 色彩及饱和度，指定像素的颜色
23     int ch1[] = {1, 0};
24     cv::mixChannels(&img_yuv, 1, &dst, 1, ch1, 1);
25     cv::imshow("yuv-u", dst);
26     int ch2[] = {2, 0};
27     cv::mixChannels(&img_yuv, 1, &dst, 1, ch2, 1);
28     cv::imshow("yuv-v", dst);
29
30     // YCrCb color space
31     cv::Mat ycrb;
32     cv::cvtColor(src, ycrb, CV_BGR2YCrCb);
33     std::vector<cv::Mat> mv;
34     cv::split(ycrb, (std::vector<cv::Mat>&) mv);
35
36     // Y channel
37     cv::Mat chy(src.rows, src.cols, CV_8UC1);
38     chy = mv[0].clone();
39     cv::imshow("Y", chy);
40     // Cr and Cb channel
41     // Cr反映RGB输入信号红色部分与RGB信号亮度值之间的差异
42     // Cb反应RGB输入信号蓝色部分与RGB信号亮度值之间的差异
43     cv::Mat chu(src.rows, src.cols, CV_8UC1);
44     chu = mv[1].clone();
45     cv::imshow("Cr", chu);
46     cv::Mat chv(src.rows, src.cols, CV_8UC1);
47     chv = mv[2].clone();
48     cv::imshow("Cb", chv);
49     cv::waitKey(0);
50
51     return 0;
52 }

#define CV_8U 0
#define CV_8S 1
#define CV_16U 2
#define CV_16S 3
#define CV_32S 4
#define CV_32F 5
#define CV_64F 6
#define CV_USRTYPE1 7

CV_8U - 8-bit unsigned integers ( 0..255 )
CV_8S - 8-bit signed integers ( -128..127 )
CV_16U - 16-bit unsigned integers ( 0..65535 )
CV_16S - 16-bit signed integers ( -32768..32767 )
CV_32S - 32-bit signed integers ( -2147483648..2147483647 )
CV_32F - 32-bit floating-point numbers ( -FLT_MAX..FLT_MAX, INF, NAN )
CV_64F - 64-bit floating-point numbers ( -DBL_MAX..DBL_MAX, INF, NAN )

void cv::transform (InputArray src,OutputArray dst,InputArray m
)The function cv::transform performs the matrix transformation of every element of the array src and stores the results in dst :???(I)=?⋅???(I)    (when m.cols=src.channels()), or???(I)=?⋅[???(I);1]    (when m.cols=src.channels()+1)Every element of the N-channel array src is interpreted as N-element vector that is transformed using the MxN or Mx(N+1) matrix m to M-element vector - the corresponding element of the output array dst.The function may be used for geometrical transformation of N-dimensional points, arbitrary linear color space transformation(such as various kinds of RGB to YUV transforms), shuffling the image channels, and so forth.Parameterssrc    input array that must have as many channels(1 to 4) as m.cols or m.cols-1.dst    output array of the same size and depth as src; it has as many channels as m.rows.m    transformation 2x2 or 2x3 floating-point matrix.