opencv编程笔记

1.读取、显示和保存图像 （imread、 imshow、 imwrite）

#include<iostream>
#include<opencv2\opencv.hpp>

using namespace std;
using namespace cv;

int main() {
Mat image = imread("d:/img/1.jpg", 0);

imshow("Image", image);
waitKey(0);
return 0;
}

2.翻转 flip(image, result, 1);（正数-水平；0-垂直；负数-同时）

3.图像 赋值 和 拷贝：

image2 = result; //两个图像指向相同的数据

result.copyTo(image3); // 产生一个新的拷贝图像

4.存取图像 img.at(j, i)[0]=intensity

5.遍历图像（指针 ptr[]，迭代器 Iterator，引用， LUT(I, lookUpTable, J)）

补充：计时 t = (double)getTickCount()；…；t = ((double)getTickCount() - t) / getTickFrequency();

高效：指针 ptr[]

Mat& ScanImageAndReduceC(Mat& I, const uchar* const table)
{
// accept only char type matrices
CV_Assert(I.depth() != sizeof(uchar));

int channels = I.channels();

int nRows = I.rows;
int nCols = I.cols * channels;

if (I.isContinuous())
{
nCols *= nRows;
nRows = 1;
}

int i,j;
uchar* p;
for( i = 0; i < nRows; ++i)
{
p = I.ptr<uchar>(i);
for ( j = 0; j < nCols; ++j)
{
p[j] = table[p[j]];
}
}
return I;
}

安全：迭代器Iterator

Mat& ScanImageAndReduceIterator(Mat& I, const uchar* const table)
{
// accept only char type matrices
CV_Assert(I.depth() != sizeof(uchar));

const int channels = I.channels();
switch(channels)
{
case 1:
{
MatIterator_<uchar> it, end;
for( it = I.begin<uchar>(), end = I.end<uchar>(); it != end; ++it)
*it = table[*it];
break;
}
case 3:
{
MatIterator_<Vec3b> it, end;
for( it = I.begin<Vec3b>(), end = I.end<Vec3b>(); it != end; ++it)
{
(*it)[0] = table[(*it)[0]];
(*it)[1] = table[(*it)[1]];
(*it)[2] = table[(*it)[2]];
}
}
}

return I;
}

引用

Mat& ScanImageAndReduceRandomAccess(Mat& I, const uchar* const table)
{
// accept only char type matrices
CV_Assert(I.depth() != sizeof(uchar));

const int channels = I.channels();
switch(channels)
{
case 1:
{
for( int i = 0; i < I.rows; ++i)
for( int j = 0; j < I.cols; ++j )
I.at<uchar>(i,j) = table[I.at<uchar>(i,j)];
break;
}
case 3:
{
Mat_<Vec3b> _I = I;

for( int i = 0; i < I.rows; ++i)
for( int j = 0; j < I.cols; ++j )
{
_I(i,j)[0] = table[_I(i,j)[0]];
_I(i,j)[1] = table[_I(i,j)[1]];
_I(i,j)[2] = table[_I(i,j)[2]];
}
I = _I;
break;
}
}

return I;
}