flipcode进行图像简单反转实现

flip函数

Flips a 2D array around vertical, horizontal, or both axes.

• C++: void flip(InputArraysrc, OutputArraydst, int flipCode)
  

• C:   void cvFlip(const CvArr*src, CvArr*dst=NULL, intflip_mode=0)

Parameters:

• src - input array
• dst - output array of the same size and type as src.
• flipCode -  a flag to specify how to flip the array; 0 means flipping around the x-axis and positive value (for example, 1) means flipping around y-axis. Negative value (for example, -1) means flipping around both axes (see the discussion below for the formulas).

The function flip flips the array in one of three different ways (row and column indices are 0-based):

The example scenarios of using the function are the following:

• Vertical flipping of the image (flipCode==0) to switch between top-left and bottom-left image origin. This is a typical operation in video processing on Microsoft Windows* OS.
• Horizontal flipping of the image with the subsequent horizontal shift and absolute difference calculation to check for a vertical-axis symmetry (flipCode>0).
• Simultaneous horizontal and vertical flipping of the image with the subsequent shift and absolute difference calculation to check for a central symmetry (flipCode<0).
• Reversing the order of point arrays (flipCode>0 orflipCode==0).

（上述对函数Flip描述来自 <<The OpenCV Reference Manual,Release2.4.3>> P.130-P.131）

测试代码：

[cpp]  view plain copy print ?

1. // CookbookMatImage.cpp : Defines the entry point for the console application.  
2. // The cookbook: Computer Vision Programming using the OpenCV Library.  
3. // by Robert Laganiere, Packt Publishing, 2011.  
4. // Copyright (C) 2013-2015 Gavin Liu,  http://blog.youkuaiyun.com/songzitea  
5.   
6. #include "stdafx.h"  
7. #include "opencv2\core\core.hpp"  
8. #include "opencv2\highgui\highgui.hpp"  
9.   
10. int main(   )   
11. {  
12.     cv::Mat image;  // create image  
13.         cv::Mat result;  
14.          
15.         image = cv::imread("monument.jpg");    // open image  
16.   
17.     // check if image has been successfully read  
18.     if (!image.data)    return 0;  
19.   
20.     cv:: cv::flip(image,result,1);  
21.     cv::namedWindow("Flip Image"); // define the window  
22.         cv::imshow("Flip Image", result); // display the Flip image  
23.       
24.     cv::waitKey(0); // wait for key pressed  
25. }  

测试输出结果： 

原始图像

不同参数flipCode如下图所示：

图1 flopcode 大于0

图2 flopcode等于0

图3 flopcode小于0

如果我们在.NET+OpenCV中进行对图像反转时，我们可以使用flip函数中的flipCode参数达到简单的反转目的。