opencv实现matlab的conv2函数

enum ConvolutionType {   
/* Return the full convolution, including border */
  CONVOLUTION_FULL, 

/* Return only the part that corresponds to the original image */
  CONVOLUTION_SAME,

/* Return only the submatrix containing elements that were not influenced by the border       
*/
  CONVOLUTION_VALID
};

void conv2(const Mat &img, const Mat& kernel, ConvolutionType type, Mat& dest) {
  Mat source = img;
  if(CONVOLUTION_FULL == type) {
    source = Mat();
    const int additionalRows = kernel.rows-1, additionalCols = kernel.cols-1;
    copyMakeBorder(img, source, (additionalRows+1)/2, additionalRows/2,     
(additionalCols+1)/2, additionalCols/2, BORDER_CONSTANT, Scalar(0));
  }

  Point anchor(kernel.cols - kernel.cols/2 - 1, kernel.rows - kernel.rows/2 - 1);
  int borderMode = BORDER_CONSTANT;
  filter2D(source, dest, img.depth(), flip(kernel), anchor, 0, borderMode);

  if(CONVOLUTION_VALID == type) {
    dest = dest.colRange((kernel.cols-1)/2, dest.cols - kernel.cols/2)
           .rowRange((kernel.rows-1)/2, dest.rows - kernel.rows/2);
  }
}