OpenCv学习笔记（一）：图像金字塔之初步理解

所谓图像金字塔，其实说起来很简单，只不过被一些所谓的玩弄学术的人弄的比较学术了而已，其实就是一句话，就是在不同的图像尺寸下对图像进行处理。比如图像本身是1024*768的，先在原图像上进行处理，再把图像缩小到512*384，处理，再降成256*192的，再处理。依次类推。而且在OpenCv中有现成的函数pyrDown供使用，如果提升的话可以用pyrUp，由于比较简单，不解释。不过理解图像金塔绝对是理解人眼特性，从事机器学习的入门级任务！现提供示例源代码如下：

#include "stdafx.h"

#include "opencv2/imgproc/imgproc.hpp"

#include "opencv2/highgui/highgui.hpp"

#include <math.h>

#include <stdlib.h>

#include <stdio.h>

using namespace cv;

/// Global variables

Mat src, dst, tmp;

char* window_name = "Pyramids Demo";

/**

* @function main

*/

int main( int argc, char** argv )

{

/// General instructions

printf( "\n Zoom In-Out demo \n " );

printf( "------------------ \n" );

printf( " * [u] -> Zoom in \n" );

printf( " * [d] -> Zoom out \n" );

printf( " * [ESC] -> Close program \n \n" );

/// Test image - Make sure it s divisible by 2^{n}

src = imread( "E:\\OPENCV\\opencv\\samples\\cpp\\tutorial_code\\images\\chicky_512.png" );

cvtColor(src,src,CV_RGB2YCrCb);

if( !src.data )

{ printf(" No data! -- Exiting the program \n");

return -1; }

vector<Mat> mv;

split(src,mv);

//tmp = src;

//dst = tmp;

tmp=mv[0];

dst=tmp;

/// Create window

namedWindow( window_name, CV_WINDOW_AUTOSIZE );

//imshow( window_name, dst );

imshow( window_name, mv[0] );

waitKey();

for(int i=0;i<3;i++)

{

pyrDown( tmp, dst, Size( tmp.cols/2, tmp.rows/2 ) );

tmp = dst;

printf( "** Zoom Out: Image / 2 \n" );

}

imshow( window_name, dst );

waitKey();

for(int i=0;i<3;i++)

{ pyrUp( tmp, dst, Size( tmp.cols*2, tmp.rows*2 ) );

tmp = dst;

printf( "** Zoom In: Image x 2 \n" );

}

dst=mv[0]-tmp;

//cvtColor(dst,dst,CV_RGB2GRAY);

//normalize(dst,dst,0,1);

imshow( window_name, dst);

waitKey(0);

return 0;

}