opencvC++学习4像素操作

opencvC++学习4像素操作

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读读一个GRAY像素点的像素值（CV_8UC1）

Scalar intensity = img.at(y, x);
或者 Scalar intensity = img.at(Point(x, y));

读一个RGB像素点的像素值
Vec3f intensity = img.at(y, x);
float blue = intensity.val[0];
float green = intensity.val[1];
float red = intensity.val[2];写像素

修改像素值

灰度图像
img.at(y,x) = 128;
RGB三通道图像
img.at(y,x)[0]=128;// blue
img.at(y,x)[1]=128;// green
img.at(y,x)[2]=128;// red
空白图像赋值
img = Scalar(0);
ROI选择
Rect r(10, 10, 100, 100);
Mat smallImg = img(r);

Vec3b与Vec3F

Vec3b对应三通道的顺序是blue、green、red的uchar类型数据。
Vec3f对应三通道的float类型数据
把CV_8UC1转换到CV32F1实现如下：
src.convertTo(dst, CV_32F);

代码：

#include 

using namespace  cv;
using namespace  std;


char INPUT_WIN[] = "input_image";
char OUTPUT_WIN[] = "output_image";

int main()
{

    Mat src = imread("D:/opencvSRC/test.jpg");
    if( !src.data ){

        cout << "imread error1" << endl;
        return -1;
    }

    namedWindow(INPUT_WIN, WINDOW_AUTOSIZE);
    imshow(INPUT_WIN, src);


    //单通道
    Mat dst1;
    cvtColor(src, dst1, CV_BGR2GRAY);
    int height = src.rows;
    int width = src.cols;
    int channels = dst1.channels();


    for (int row = 0; row < height; row++) {
        for (int col = 0; col < width; col++) {
            if (channels == 1) {

                int gray = dst1.at(row, col);
                dst1.at(row, col) = 255 - gray;
            }
        }
    }
    namedWindow("output1", CV_WINDOW_AUTOSIZE);
    imshow("output1", dst1);

    //三通道
    Mat dst;
    dst.create(src.size(), src.type());
    channels = dst.channels();
    printf("height=%d width=%d channels=%d", height, width, channels);
    for (int row = 0; row < height; row++) {
        for (int col = 0; col < width; col++) {
            if (channels == 3) {
                int b = src.at(row, col)[0];
                int g = src.at(row, col)[1];
                int r = src.at(row, col)[2];

                dst.at(row, col)[0] = 255 - b;
                dst.at(row, col)[1] = 255 - g;
                dst.at(row, col)[2] = 255 - r;
            }
        }
    }
    namedWindow("output", CV_WINDOW_AUTOSIZE);
    imshow("output", dst);

    //一个函数解决
    Mat dst2;
    dst2.create(src.size(), src.type());

    bitwise_not(src, dst2);
    namedWindow("output2", CV_WINDOW_AUTOSIZE);
    imshow("output2", dst2);



    waitKey(0);

    return 0;
}