在OpenCV 2.1中:如何将一个矩阵分配给另一个矩阵的子矩阵? [英] In OpenCV 2.1: How to assign a matrix to a submatrix of another matrix?

问题描述

假设我有一个矩阵

A = cv::Mat(3,3,CV_32F) 

和矩阵

B = cv::Mat(2,2,CV_32F).

比方说，A的全为零，B的全为零. 我想将B的值分配给A的左上角.我该怎么做?

Let's say A has all zeros and B has all ones. I want to assign the values of B to the upper left corner of A. How can I do this?

我尝试了以下操作:

A(cv::Rect_<int>(0,0,2,2)) = B

但这似乎不起作用.但是，通过这种方式将标量值分配给A的subrect确实可行:

But this doesn't seem to work. However assigning a scalar value to the subrect of A this way does work:

A(cv::Rect_<int>(0,0,2,2)) = 1.0

第一种方法有什么问题?

What is wrong with the first approach?

推荐答案

我更喜欢单线，但这可以解决问题:

I'd prefer a one-liner, but this does the trick:

cv::Mat tmp = A(cv::Rect(0,0,2,2));
B.copyTo(tmp);

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