opencv 显示图片

目录

opencv显示图片

imread，读取图片

 namedWindow，创建窗口

imshow，显示图片 

waitKey，等待窗口关闭

destroyAllWindows，销毁窗口

#include 

using namespace cv;

int main(int argc, char** argv) {
	Mat src = imread("E://images//test.jpg");
	if (src.empty()) {
		printf("未能找到图片n");
		return -1;
	}
	namedWindow("显示图片", WINDOW_AUTOSIZE);
	imshow("显示图片", src);
	waitKey(0);
	destroyAllWindows();
	return 0;
}

imread，读取图片

Mat imread( const String& filename, int flags = IMREAD_COLOR );

参数一 filename类型const String& ，是图片的位置，不能直接复制图片的位置E:imagestest.jpg，应该将''转换为‘/’或“//”;

参数二 flags 类型int，图片加载类型

常用有

• 默认为IMREAD_COLOR，加载彩色图片
• IMREAD_UNCHANGED 原样加载，新版已废弃
• IMREAD_GRAYSCALE转换为灰色图片
• IMREAD_ANYDEPTH 加载原深度
• IMREAD_ANYCOLOR 加载原颜色

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

 namedWindow，创建窗口

void namedWindow(const String& winname, int flags = WINDOW_AUTOSIZE);

 参数一winname类型const String& ，窗口名称

参数二flags类型flags，窗口类型

WINDOW_NORMAL	the user can resize the window (no constraint) / also use to switch a fullscreen window to a normal size.
WINDOW_AUTOSIZE	the user cannot resize the window, the size is constrainted by the image displayed.
WINDOW_OPENGL	window with opengl support.
WINDOW_FULLSCREEN	change the window to fullscreen.
WINDOW_FREERATIO	the image expends as much as it can (no ratio constraint).
WINDOW_KEEPRATIO	the ratio of the image is respected.
WINDOW_GUI_EXPANDED	status bar and tool bar
WINDOW_GUI_NORMAL	old fashious way

imshow，显示图片 

void imshow(const String& winname, InputArray mat);

 参数一winname类型const String& ，窗口名称

参数二mat类型InputArray，显示图片

waitKey，等待窗口关闭

int waitKey(int delay = 0);

参数delay，等待用户按键时间，单位毫秒，在delay时间内用户按键或等待时间超过delay，窗口自动退出，0表示一直等待用户按键

destroyAllWindows，销毁窗口

void destroyAllWindows();