opencv学习笔记2 拖动条，亮度对比度 颜色空间缩减 鼠标事件

#include <opencv2/core/core.hpp>
#include<opencv2/highgui/highgui.hpp>
#include"opencv2/imgproc/imgproc.hpp"
#include <iostream>

using namespace std;
using namespace cv;

static void ContrastAndBright(int, void *);

int g_nContrastValue; //对比度值
int g_nBrightValue;  //亮度值
Mat g_srcImage, g_dstImage;

int main()
{
    //读入用户提供的图像
    g_srcImage = imread("E:/test.jpg");

    g_dstImage = Mat::zeros(g_srcImage.size(), g_srcImage.type());

    //设定对比度和亮度的初值
    g_nContrastValue = 80;
    g_nBrightValue = 80;

    //创建窗口
    namedWindow("【效果图窗口】", 1);

    //创建轨迹条
    createTrackbar("对比度：", "【效果图窗口】", &g_nContrastValue, 300, ContrastAndBright);
    createTrackbar("亮   度：", "【效果图窗口】", &g_nBrightValue, 200, ContrastAndBright);

    //调用回调函数
    ContrastAndBright(g_nContrastValue, 0);
    ContrastAndBright(g_nBrightValue, 0);
        waitKey();    
    return 0;
}


static void ContrastAndBright(int, void *)
{

    //创建窗口
    namedWindow("【原始图窗口】", 1);

    //三个for循环，执行运算 g_dstImage(i,j) =a*g_srcImage(i,j) + b
    for (int y = 0; y < g_srcImage.rows; y++)
    {
        for (int x = 0; x < g_srcImage.cols; x++)
        {
            for (int c = 0; c < 3; c++)
            {
                g_dstImage.at<Vec3b>(y, x)[c] = saturate_cast<uchar>((g_nContrastValue*0.01)*(g_srcImage.at<Vec3b>(y, x)[c]) + g_nBrightValue); //改变每个像素每个通道的值
            }
        }
    }

    //显示图像
    imshow("【原始图窗口】", g_srcImage);
    imshow("【效果图窗口】", g_dstImage);
}


颜色空间缩减

//使用动态地址遍历    
for (int i = 0; i < src.rows; i++)
    {
        for (int j = 0; j < src.cols; j++)
        {
            for (int c = 0; c < 3; c++)
            {
                dst.at<Vec3b>(i, j)[c] = (src.at<Vec3b>(i, j)[c] / div) *div; //每10个像素变为一个。 0-9->0 10-19->10
            }
        }
    }

//使用迭代器遍历
dst = src.clone();
    Mat_<Vec3b>::iterator it = dst.begin<Vec3b>();
    Mat_<Vec3b>::iterator itend = dst.end<Vec3b>();
    for (; it != itend; it++)
    {
        for (int i = 0; i < 3; i++)
        {
            (*it)[i] = (*it)[i] / 10 * 10;
        }
    }

//使用鼠标画图

#include<opencv.hpp>
#include<iostream>
using namespace std;
using namespace cv;
#define WINDOW_NAME "程序窗口"
Rect g_rectangle;
bool is_Press = false;
RNG g_rng(12345);


void DrawRectangle(cv::Mat& img, cv::Rect box)
{
    rectangle(img, box.tl(), box.br(), Scalar(g_rng.uniform(0, 255),
        g_rng.uniform(0, 255), g_rng.uniform(0, 255)));
}
void on_MouseHandle(int event,int x,int y,int flags,void* param)
{
    Mat& image = *(cv::Mat*)param;
    switch (event)
    {
    case EVENT_MOUSEMOVE:
    {
        if (is_Press)
        {
            g_rectangle.width = x - g_rectangle.x;
            g_rectangle.height = y - g_rectangle.y;
        }
    }
    break;
    case EVENT_LBUTTONDOWN:
    {
        is_Press = true;
        g_rectangle.x = x;
        g_rectangle.y = y;
    }
    break;
    case EVENT_LBUTTONUP:
    {
        is_Press = false;
        if (g_rectangle.width < 0)
        {
            g_rectangle.x += g_rectangle.width;
            g_rectangle.width *= -1;
        }
        if (g_rectangle.height < 0)
        {
            g_rectangle.y += g_rectangle.height;
            g_rectangle.height *= -1;
        }
        DrawRectangle(image, g_rectangle);
    }
    break;
    }
}

int main()
{
    g_rectangle = Rect(-1, -1, 0, 0);
    Mat srcImage(600, 800, CV_8UC3), tmpImage;
    srcImage.copyTo(tmpImage);
    srcImage = Scalar::all(0);
    
    namedWindow(WINDOW_NAME);
    setMouseCallback(WINDOW_NAME, on_MouseHandle, (void*)& srcImage);
    while (1)
    {
        srcImage.copyTo(tmpImage);
        if (is_Press)
            DrawRectangle(tmpImage, g_rectangle);
        imshow(WINDOW_NAME, tmpImage);
        if (waitKey(10) == 27)
            break;
    }
    return 0;
}