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OpenCV - zero matrix filling

Suppose I have a small_image mat variable with dimensions 98x158x32 (type float). Now I want the null pad to be this image (i.e. add a border of zeros to the image). I want to add 7 zeros above and below the image and 12 zeros to the left and right of the image. The first idea was to use a copyMakeBorder summary (see copyMakeBorder document ), which seems to be perfect for this:

    int old_size[3];
    old_size[0] = 98;
    old_size[1] = 158;
    old_size[2] = 32;

    int pad_size[3];
    pad_size[0] = old_size[0] + 2 * 7;
    pad_size[1] = old_size[1] + 2 * 12;
    pad_size[2] = old_size[2];

    cv::Mat image_padded(3, pad_size, CV_32FC1, cv::Scalar(0)); //Initialize the larger Mat to 0

    copyMakeBorder(small_image,image_padded,7,7,12,12,BORDER_CONSTANT,Scalar(0));

However, this code gives a memcopy error. Does anyone see a problem here?

The alternative described in this post also does not work:

cv::Rect roi( cv::Point( 12, 7 ), small_image.size() );
small_image.copyTo( image_padded( roi ) );

He claims that "Assertion failed (m.dims <= 2)" and both Mat variables are 3D matrices.

Any help to achieve zero fill would be greatly appreciated!

+4
2

, 2D . 3D Mat, . (), copyTo, .

#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>

int main()
{
  int old_size[3];
  old_size[0] = 5;
  old_size[1] = 5;
  old_size[2] = 2;

  int pad_size[3];
  pad_size[0] = old_size[0] + 2 * 1;
  pad_size[1] = old_size[1] + 2 * 2;
  pad_size[2] = old_size[2];

  cv::Mat small_image(3, old_size, CV_32FC1, cv::Scalar(1));
  cv::Mat image_padded(3, pad_size, CV_32FC1, cv::Scalar(0));

  cv::Range ranges[3];
  ranges[0] = cv::Range(1, old_size[0]+1);
  ranges[1] = cv::Range(2, old_size[1]+2);
  ranges[2] = cv::Range(0, old_size[2]);

  small_image.copyTo(image_padded(ranges));

  for (int i = 0; i < pad_size[0]; i++)
    for (int j = 0; j < pad_size[1]; j++)
      for (int k = 0; k < pad_size[2]; k++)
        std::cout << image_padded.at<float>(i, j, k) << ", ";
}

:

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 
0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+2

rowRange colRange, ( ). .

cv::Mat image_padded(3, pad_size, CV_32FC1, cv::Scalar(0));
int xPad = 12;
int yPad = 7;
Mat area = image_padded.rowRange(xPad, xPad + 98).colRange(yPad, yPad + 158);
small_image.copyTo( area );
+1

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