opencv 图像读取、显示

小白学视觉，笔记


代码测试

#include "opencv2/opencv.hpp"
#include 

using namespace cv;
using namespace std;

int main()
{
    //图片属性下的路径，E:\Progarm\Images\17.jpg，斜杠需要修改
    //需要修改为\\或者/或者//

    Mat img = imread("E:/Progarm/Images/17.jpg", IMREAD_COLOR);//IMREAD_COLOR==0单通道，灰度图
    Mat gray = imread("E:\\Progarm\\Images\\17.jpg", IMREAD_GRAYSCALE);//IMREAD_GRAYSCALE==1三通道，彩图,可不写默认值为1

 
    namedWindow("img",WINDOW_NORMAL);//标注的，显示图片全景，可调整窗口的大小(没有限制)，整幅图跟着缩放，/也可以用来将全屏窗口切换到正常大小。  
    namedWindow("gray", WINDOW_AUTOSIZE); //自动，不能调整窗口的大小，如果图片太大，只能显示窗口内的一部分，该大小受显示图像的限制。

    imshow("img",img);
    imshow("gray", gray);
    
    waitKey(0);//（图像显示窗口关闭之后）等待按键按下，程序结束
    return 0;

}

如图，彩色图片窗口是WINDOW_NORMAL，可以自由鼠标拉伸大小
灰色图WINDOW_AUTOSIZE，不可调节

enum ImreadModes {
       IMREAD_UNCHANGED            = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped). Ignore EXIF orientation.
       IMREAD_GRAYSCALE            = 0,  //!< If set, always convert image to the single channel grayscale image (codec internal conversion).
       IMREAD_COLOR                = 1,  //!< If set, always convert image to the 3 channel BGR color image.
       IMREAD_ANYDEPTH             = 2,  //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
       IMREAD_ANYCOLOR             = 4,  //!< If set, the image is read in any possible color format.
       IMREAD_LOAD_GDAL            = 8,  //!< If set, use the gdal driver for loading the image.
       IMREAD_REDUCED_GRAYSCALE_2  = 16, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/2.
       IMREAD_REDUCED_COLOR_2      = 17, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.
       IMREAD_REDUCED_GRAYSCALE_4  = 32, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/4.
       IMREAD_REDUCED_COLOR_4      = 33, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.
       IMREAD_REDUCED_GRAYSCALE_8  = 64, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/8.
       IMREAD_REDUCED_COLOR_8      = 65, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/8.
       IMREAD_IGNORE_ORIENTATION   = 128 //!< If set, do not rotate the image according to EXIF's orientation flag.
     };

enum WindowFlags {
       WINDOW_NORMAL     = 0x00000000, //!< the user can resize the window (no constraint) / also use to switch a fullscreen window to a normal size.
       WINDOW_AUTOSIZE   = 0x00000001, //!< the user cannot resize the window, the size is constrainted by the image displayed.
       WINDOW_OPENGL     = 0x00001000, //!< window with opengl support.

       WINDOW_FULLSCREEN = 1,          //!< change the window to fullscreen.
       WINDOW_FREERATIO  = 0x00000100, //!< the image expends as much as it can (no ratio constraint).
       WINDOW_KEEPRATIO  = 0x00000000, //!< the ratio of the image is respected.
       WINDOW_GUI_EXPANDED=0x00000000, //!< status bar and tool bar
       WINDOW_GUI_NORMAL = 0x00000010, //!< old fashious way
    };

The function destroyWindow destroys the window with the given name.

@param winname Name of the window to be destroyed.
*/

CV_EXPORTS_W void destroyWindow(const String& winname);

/** @brief Destroys all of the HighGUI windows.

The function destroyAllWindows destroys all of the opened HighGUI windows.
*/

CV_EXPORTS_W void destroyAllWindows();