OpenCV快速垫元和邻居访问 [英] OpenCV fast mat element and neighbour access

问题描述

我使用OpenCV（C ++）Mat为我的矩阵，并希望尽快访问单个Mat元素。从OpenCV教程，我找到了有效的访问代码：

I use OpenCV (C++) Mat for my matrix and want to acces single Mat elements as fast as possible. From OpenCV tutorial, I found code for efficient acces:

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

对于我的问题，我需要访问一个Mat元素及其邻居（i-1，j-1）进行计算。我如何适应给定的代码访问单个垫元素及其周围的元素？由于速度很重要，我想避免 Mat.at<>（）。
什么是最有效的方法来获取Mat值及其邻域值？

For my problem, I need to access a Mat element and its neighbours (i-1,j-1) for a calculation. How can I adapt the given code to acces a single mat element AND its surrounding elements? Since speed matters, I want to avoid Mat.at<>(). What is the most efficient way to acces a Mat value and its neighbour values?

推荐答案

像素及其邻域像素可以形成一个 cv :: Rect ，那么你可以简单地使用：

The pixel and its neighbor pixels can be formed a cv::Rect, then you can simply use:

cv::Mat mat = ...;
cv::Rect roi= ...; // define it properly based on the neighbors defination
cv::Mat sub_mat = mat(roi);

如果邻居定义不规则，即它们不能形成一个矩形区域，请查看此处的示例。

In case your neighbors definition is not regular, i.e. they cannot form a rectangle area, use mask instead. Check out here for examples.

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