Clash Royale CLAN TAG#URR8PPP

How to use the OpenCV CUDA Fourier Transform

Instead of OpenCV's normal dft, I'd like to use cuda::dft. As a start I tried performing a forward and inverse transform, but the result doesn't look anything like the input. Here's a minimal example using an OpenCV example image:

dft

cuda::dft

// Load 8bit test image (https://raw.githubusercontent.com/opencv/opencv/master/samples/data/basketball1.png)
Mat testImg;
testImg = imread("basketball1.png", CV_LOAD_IMAGE_GRAYSCALE);

// Convert input to complex float image
Mat_<float> imgReal;
testImg.convertTo(imgReal, CV_32F, 1.0/255.0);
Mat imgImag = Mat(imgReal.rows, imgReal.cols, CV_32F, float(0));
vector<Mat> channels;
channels.push_back(imgReal);
channels.push_back(imgImag);
Mat imgComplex;
merge(channels,imgComplex);

imshow("Img real", imgReal);
waitKey(0);

//Perform a Fourier transform
cuda::GpuMat imgGpu, fftGpu;
imgGpu.upload(imgComplex);

cuda::dft(imgGpu, fftGpu, imgGpu.size());

//Performs an inverse Fourier transform
cuda::GpuMat propGpu, convFftGpu;
cuda::dft(fftGpu, propGpu, imgGpu.size(), DFT_REAL_OUTPUT | DFT_SCALE);

Mat output(propGpu);
output.convertTo(output, CV_8U, 255, 0);

imshow("Output", output);
waitKey(0);


I played with the flags but output never looks anything like input. Using the above code I get as output:

output

While it should look like this:

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.