图像拉普拉斯金字塔融合（Laplacian Pyramid Blending）

// 转摘的别人的程序
//

#include <stdio.h>
#include <cv.h>
#include <cxcore.h>
#include <highgui.h>
#include <opencv2/opencv.hpp>

using namespace cv;

// __func__ 和 __FUNCTION__ 一样的意思，描述当前所在的函数
#define ENABLE_DEBUG 1   //else, comment this line
#ifdef ENABLE_DEBUG
#define DEBUG_LOG(fmt,...) fprintf(stderr, "%s:%d: " fmt "\n",   \
__FUNCTION__ , __LINE__, ## __VA_ARGS__)
#else
#define DEBUG_LOG(fmt, ...) do {} while (0)
#endif

//////////////////////////////////////////////////////////////////////////
// disable stupid warning 4018 and etc...
#pragma warning(push)
#pragma warning(disable:4018)

/************************************************************************/
/* 说明：
*金字塔从下到上依次为 [0,1，...，level-1] 层
*blendMask 为图像的掩模
*maskGaussianPyramid为金字塔每一层的掩模
*resultLapPyr 存放每层金字塔中直接用左右两图Laplacian变换拼成的图像
*/
/************************************************************************/
class LaplacianBlending {
private:
Mat_<Vec3f> left;
Mat_<Vec3f> right;
Mat_<float> blendMask;

vector<Mat_<Vec3f> > leftLapPyr,rightLapPyr,resultLapPyr;//Laplacian Pyramids
Mat leftHighestLevel, rightHighestLevel, resultHighestLevel;
vector<Mat_<Vec3f> > maskGaussianPyramid; //masks are 3-channels for easier multiplication with RGB

int levels;

void buildPyramids() {
buildLaplacianPyramid(left,leftLapPyr,leftHighestLevel);
buildLaplacianPyramid(right,rightLapPyr,rightHighestLevel);
buildGaussianPyramid();
}

void buildGaussianPyramid() {//金字塔内容为每一层的掩模
assert(leftLapPyr.size()>0);

maskGaussianPyramid.clear();
Mat currentImg;
cvtColor(blendMask, currentImg, CV_GRAY2BGR);//store color img of blend mask into maskGaussianPyramid
maskGaussianPyramid.push_back(currentImg); //0-level

currentImg = blendMask;
for (int l=1; l<levels+1; l++) {
Mat _down;
if (leftLapPyr.size() > l)
pyrDown(currentImg, _down, leftLapPyr[l].size());
else
pyrDown(currentImg, _down, leftHighestLevel.size()); //lowest level

Mat down;
cvtColor(_down, down, CV_GRAY2BGR);
maskGaussianPyramid.push_back(down);//add color blend mask into mask Pyramid
currentImg = _down;
}
}

void buildLaplacianPyramid(const Mat& img, vector<Mat_<Vec3f> >& lapPyr, Mat& HighestLevel) {
lapPyr.clear();
Mat currentImg = img;
for (int l=0; l<levels; l++) {
Mat down,up;
pyrDown(currentImg, down);
pyrUp(down, up,currentImg.size());
Mat lap = currentImg - up;
lapPyr.push_back(lap);
currentImg = down;
}
currentImg.copyTo(HighestLevel);
}

Mat_<Vec3f> reconstructImgFromLapPyramid() {
//将左右laplacian图像拼成的resultLapPyr金字塔中每一层
//从上到下插值放大并相加，即得blend图像结果
Mat currentImg = resultHighestLevel;
for (int l=levels-1; l>=0; l--) {
Mat up;

pyrUp(currentImg, up, resultLapPyr[l].size());
currentImg = up + resultLapPyr[l];
}
return currentImg;
}

void blendLapPyrs() {
//获得每层金字塔中直接用左右两图Laplacian变换拼成的图像resultLapPyr
resultHighestLevel = leftHighestLevel.mul(maskGaussianPyramid.back()) +
rightHighestLevel.mul(Scalar(1.0,1.0,1.0) - maskGaussianPyramid.back());
for (int l=0; l<levels; l++) {
Mat A = leftLapPyr[l].mul(maskGaussianPyramid[l]);
Mat antiMask = Scalar(1.0,1.0,1.0) - maskGaussianPyramid[l];
Mat B = rightLapPyr[l].mul(antiMask);
Mat_<Vec3f> blendedLevel = A + B;

resultLapPyr.push_back(blendedLevel);
}
}

public:
LaplacianBlending(const Mat_<Vec3f>& _left, const Mat_<Vec3f>& _right, const Mat_<float>& _blendMask, int _levels)://construct function, used in LaplacianBlending lb(l,r,m,4);
left(_left),right(_right),blendMask(_blendMask),levels(_levels)
{
assert(_left.size() == _right.size());
assert(_left.size() == _blendMask.size());
buildPyramids();	//construct Laplacian Pyramid and Gaussian Pyramid
blendLapPyrs();	//blend left & right Pyramids into one Pyramid
};

Mat_<Vec3f> blend() {
return reconstructImgFromLapPyramid();//reconstruct Image from Laplacian Pyramid
}
};

Mat_<Vec3f> LaplacianBlend(const Mat_<Vec3f>& l, const Mat_<Vec3f>& r, const Mat_<float>& m) {
LaplacianBlending lb(l,r,m,4);
return lb.blend();
}

// 图像融合处理
void process(char *sleft, char *sright, char *sresult/*结果保存*/)
{
if (!sleft || !*sleft || !sright || !*sright)
{
return;
}

Mat l8u = imread(sleft);
Mat r8u = imread(sright);

// check file size
Size sz1 = l8u.size(),
sz2 = r8u.size();
if ( sz1 != sz2)
{
DEBUG_LOG("left and the right image must be the same size");
exit(0);
}

//
imshow("left",l8u);
imshow("right",r8u);

Mat_<Vec3f> l; l8u.convertTo(l,CV_32F,1.0/255.0);//Vec3f表示有三个通道，即 l[row][column][depth]
Mat_<Vec3f> r; r8u.convertTo(r,CV_32F,1.0/255.0);
/*****************    void convertTo( OutputArray m, int rtype, double alpha=1, double beta=0 ) const;******************/
/* Performs linear transformation on every source array element:
dst(x,y,c) = scale*src(x,y,alpha)+beta.
Arbitrary combination of input and output array depths are allowed
(number of channels must be the same), thus the function can be used
for type conversion */

//create blend mask matrix m
Mat_<float> m(l.rows,l.cols,0.0);					//将m全部赋值为0
m(Range::all(),Range(0,m.cols/2)) = 1.0;	//取m全部行&[0,m.cols/2]列，赋值为1.0

Mat_<Vec3f> blend = LaplacianBlend(l, r, m);
imshow("blended",blend);

// save result to png file
std::vector<int> qualityType;
qualityType.push_back(CV_IMWRITE_JPEG_QUALITY);
qualityType.push_back(90);    //png格式下，默认的参数为3.
if(sresult != NULL)
{
//build file name
char filename[255] = {0};
sprintf(filename, "%s.jpg", sresult);

try {
imwrite(filename, cv::Mat(blend), qualityType);
}
catch (std::runtime_error& ex) {
DEBUG_LOG("Exception converting image to PNG format: %s\n", ex.what());
exit(1);
}
DEBUG_LOG("Saved PNG file with alpha data...");
}

waitKey(0);
}

/*******************************************************************************
主函数
*******************************************************************************/
int main( int argc, char * argv[] )
{
// 调试程序，选择菜单->项目->属性->调试->命令参数,
if ( argc < 3 )
{
printf( "Usage:\n" );
printf( "LaplacianBlending LeftImage RightImage\n" );
exit( 0 );
}

DEBUG_LOG("\nleft image = %s\nright image=%s\n\n", argv[1], argv[2]);

if ( argc == 3 )
process( argv[1], argv[2], NULL );
else  // argc >= 4
process( argv[1], argv[2],argv[3]);

return 0;
}

//////////////////////////////////////////////////////////////////////////
#pragma warning(pop)