c ++ OpenCV如何将过滤器应用到Mat的子矩形？ [英] c++ OpenCV How to apply filter to sub rect of Mat?

问题描述

这个问题类似，但从未回答：图像的OpenCV过滤部分

我使用opencv2和c ++。我有一个Mat，说300x200，我想模糊 矩形中的区域，左上角= 50,50尺寸= 100,50。我一直在通过在opencv.org的示例和文档，但我不能确定如何过滤，或执行其他操作只有一个从一个子矩阵。

代码如下，其中 surf 是SDL_Surface， rect 是一个SDL_Rect（int x，y， w，h）。从表面创建 Mat src_mat 的行很好，因为它在其他地方很好。这会编译，但会出现以下错误。

  {//用于surface_lock的超范围。 
 using namespace cv; 
 surface_lock surf_lock（surf）; 
 
 // int rows，int cols，int type，void * data，size_t step = AUTO_STEP 
 Mat src_mat = Mat（surf-> h，surf-> w，CV_8UC4， src->像素，Mat :: AUTO_STEP）; 
 Mat cropmat（src_mat，Rect（rect.y，rect.y + rect.h，rect.x，rect.x + rect.w））; 
 
 blur（crop_mat，crop_mat，Size（（depth + 1），（depth + 1）），Point（-1，-1） 
} 
  

错误：

  OpenCV Error：Assertion failed（0 <= roi.x&& 0 <= roi.width&& roi.x + roi.width <= m。 Mat，& 0< = roi.y&& 0< = roi.height&&& roi.y + roi.height< = m.rows）in mat，file / build / opencv / src / opencv-2.4.6.1 / modules / core / src / matrix.cpp，第323行
在抛出'cv :: Exception'实例后调用终止
 what（）：/ build / opencv / src / opencv-2.4.6.1 / modules / core / src / matrix.cpp：323：error：（-215）0 <= roi.x& 0< = roi.width&& roi.x + roi.width <= m.cols&& 0< = roi.y&& 0< = roi.height&& roi.height <= m.rows in function Mat 
  

解决方案<

  Mat greater; 
 Mat roi（larger，Rect（50,50,100,50））; 
 
 //应用任何算法对'roi'
 blur（roi，roi，cv :: Size（5,5））; 
  

This question is similar, but never was answered: OpenCV filtering part of an image

I'm using opencv2 and c++. I have a Mat, say 300x200, and I want to blur only the area in the rectangle with top-left = 50,50 size=100,50. I've been wading through the example and docs on opencv.org, but I cannot determine how to filter, or perform other operations on only a sub-rect from a Mat.

Code in question is below, where surf is an SDL_Surface and rect is an SDL_Rect (int x,y,w,h). The line with the creation of Mat src_mat from the surface is fine as it works well elsewhere. This compiles, but gives the following error.

{ // Extra scoping used for the surface_lock.
    using namespace cv;
    surface_lock surf_lock(surf);

    //int rows, int cols, int type, void* data, size_t step=AUTO_STEP
    Mat src_mat = Mat(surf->h, surf->w, CV_8UC4, src->pixels, Mat::AUTO_STEP);
    Mat cropmat(src_mat, Rect(rect.y, rect.y + rect.h, rect.x, rect.x + rect.w));

    blur(crop_mat, crop_mat, Size((depth + 1), (depth + 1)), Point(-1,-1));
}

error:

OpenCV Error: Assertion failed (0 <= roi.x && 0 <= roi.width && roi.x + roi.width <= m.cols && 0 <= roi.y && 0 <= roi.height && roi.y + roi.height <= m.rows) in Mat, file /build/opencv/src/opencv-2.4.6.1/modules/core/src/matrix.cpp, line 323
terminate called after throwing an instance of 'cv::Exception'
  what():  /build/opencv/src/opencv-2.4.6.1/modules/core/src/matrix.cpp:323: error: (-215) 0 <= roi.x && 0 <= roi.width && roi.x + roi.width <= m.cols && 0 <= roi.y && 0 <= roi.height && roi.y + roi.height <= m.rows in function Mat

解决方案

a subrect is a Mat, too.

Mat larger; 
Mat roi(larger, Rect(50,50,100,50));

// apply whatever algo on 'roi'
blur( roi,roi, cv::Size(5,5) );

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