OpenCV：矩阵迭代 [英] OpenCV: Matrix Iteration

问题描述

我是OpenCV的新手。我试图使用迭代器而不是for循环，这对我的情况来说太慢了。我试过这样的代码：

  MatIterator_< uchar>它，结束; 
 for（it = I.begin< uchar>（），end = I.end< uchar>（）; it！= end; ++ it）
 {
 // some codes这里
} 
  

我的问题是：如何转换for循环，如：<对于（int i = 0; i< 500; i ++）
{
exampleMat。 at< int>（i）= srcMat> .at< int>（i + 2，i + 3）
}

进入迭代器模式？也就是说，如何以迭代器形式执行i + 2，i + 3？我只能通过* it得到相应的值，但我无法得到它的计数数字。
非常感谢提前。

解决方案

这不是for循环，它是 exampleMat.at< int>（i ）正在进行范围检查。

要有效地遍历所有像素，您可以获得指向每行开头的数据的指针with .ptr（）

  for（int row = 0; row< img.rows; ++ row）{
 uchar * p = img.ptr（row）; 
 for（int col = 0; col< img.cols; ++ col）{
 * p ++ //指向每个像素值，假设CV_8UC1灰度图像
} 
 
或
 for（int col = 0; col< img.cols * 3; ++ col）{
 * p ++ //指向每个像素B，G，R值假设CV_8UC3彩色图像
} 
 
} 
  

I am new to OpenCV. I am trying to use iterator instead of "for" loop, which is too slow for my case. I tried some codes like this:

MatIterator_<uchar> it, end;
for( it = I.begin<uchar>(), end = I.end<uchar>(); it != end; ++it)
{
    //some codes here
}

My question here is: how can I convert a for loop like:

for ( int i = 0; i < 500; i ++ )
{
    exampleMat.at<int>(i) = srcMat>.at<int>( i +2, i + 3 )
}

into iterator mode? That is, how can I do the "i +2, i + 3" in iterator form? I only can get the corresponding value by " *it " I think, but I couldn't get its counting number. Many thanks in advance.

解决方案

It's not the for loop which is slow it is the exampleMat.at<int>(i) which is doing range checking.

To efficently loop over all the pixels you can get a pointer to the data at the start of each row with .ptr()

for(int row = 0; row < img.rows; ++row) {
    uchar* p = img.ptr(row);
    for(int col = 0; col < img.cols; ++col) {
         *p++  //points to each pixel value in turn assuming a CV_8UC1 greyscale image 
    }

    or 
    for(int col = 0; col < img.cols*3; ++col) {
         *p++  //points to each pixel B,G,R value in turn assuming a CV_8UC3 color image 
    }

}   

这篇关于OpenCV：矩阵迭代的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！