图像 DFT 尺寸转换

const int nRows = srcImage.rows;
  const int nCols = srcImage.cols;
  std::cout << "srcImage row:" << nRows << std::endl;
  std::cout << "srcImage col:" << nCols << std::endl;
  // 获取DFT尺寸
  int cRows = cv::getOptimalDFTSize(nRows);
  int cCols = cv::getOptimalDFTSize(nCols);
  std::cout << "DFT srcImage row:" << cRows << std::endl;
  std::cout << "DFT srcImage col:" << cCols << std::endl;
  // 图像拷贝，超过边界区域填充为0
  cv::Mat sizeConvMat;
  copyMakeBorder(srcImage, sizeConvMat, 0, cRows -nRows,
     0, cCols-nCols, cv::BORDER_CONSTANT, cv::Scalar::all(0)); 
  cv::imshow("sizeConvMat", sizeConvMat);

转载：http://blog.youkuaiyun.com/zhuwei1988