OpenCV学习笔记——imread、imwrite以及imshow

1、imread

Loads an image from a file. 从文件中读取图像。

C++: Mat imread(const string& filename, int flags=1 )

Parameters: 参数：

filename – Name of file to be loaded. 文件名
flags –
Flags specifying the color type of a loaded image:
- >0 Return a 3-channel color image 返回一个三通道的图像
- =0 Return a grayscale image 返回灰度图像
- <0 Return the loaded image as is. Note that in the current implementation the alpha channel, if any, is stripped from the output image. For example, a 4-channel RGBA image is loaded as RGB if $flagsge0$ .

2、imwrite

Saves an image to a specified file. 把图像保存到特定路径下。

C++: bool imwrite(const string& filename, InputArray image, const vector<int>& params=vector<int>())
Parameters:

filename – Name of the file. 文件名
image – Image to be saved. 图像
params –
Format-specific save parameters encoded as pairs paramId_1, paramValue_1, paramId_2, paramValue_2, ... . The following parameters are currently supported:
- For JPEG, it can be a quality ( CV_IMWRITE_JPEG_QUALITY ) from 0 to 100 (the higher is the better). Default value is 95. 对于JPEG，图像质量。
- For PNG, it can be the compression level ( CV_IMWRITE_PNG_COMPRESSION ) from 0 to 9. A higher value means a smaller size and longer compression time. Default value is 3. 对于PNG，压缩等级。
- For PPM, PGM, or PBM, it can be a binary format flag ( CV_IMWRITE_PXM_BINARY ), 0 or 1. Default value is 1.

3、imshow

Displays an image in the specified window. 在特定的窗口上显示图像。

C++: void imshow(const string& winname, InputArray image)

Parameters:

winname – Name of the window. 窗口名称。
image – Image to be shown. 要显示的图像。

[1] http://www.opencv.org.cn/opencvdoc/2.3.2/html/doc/tutorials/core/mat%20-%20the%20basic%20image%20containe/mat%20-%20the%20basic%20image%20container.html#matthebasicimagecontainer