Fourier transformation in frequency domain with opencv

Question

I'm trying to implement the fourier transformation in frequency domain. I used getOptimalDFTSize accordingly, and I copied the image and mask, in bigger images, suitable for fourier transformation. I used the sample code from here as a reference.
Now, I have to separate the real and imaginary part, and to perform pixelwise multiplication of the image imaginary part with the mask imaginary part, and the same for the real part.But when I try to do so, I get the following error message:

OpenCV Error: Assertion failed (type == srcB.type() && srcA.size() == srcB.size()) in mulSpectrums, file /build/buildd/opencv-2.1.0/src/cxcore/cxdxt.cpp, line 1855 /build/buildd/opencv-2.1.0/src/cxcore/cxdxt.cpp:1855: error: (-215) type == srcB.type() && srcA.size() == srcB.size() in function mulSpectrums

The code is following:

//fourier transfromation of real and imaginary part
Mat complex_image, real_image, complex_mask, real_mask;

cv::dft(new_image, complex_image, DFT_COMPLEX_OUTPUT);
cv::dft(new_image, real_image, DFT_REAL_OUTPUT);

cv::dft(new_mask, complex_mask, DFT_COMPLEX_OUTPUT);
cv::dft(new_mask, real_mask, DFT_REAL_OUTPUT);



//pixelwise multiplication
Mat multiplied_complex, multiplied_real;
cv::mulSpectrums(complex_image, complex_mask, multiplied_complex, DFT_COMPLEX_OUTPUT );
cv::mulSpectrums(real_image, real_mask, multiplied_real, DFT_REAL_OUTPUT);

What am I doing wrong here?

Pol · Accepted Answer · 2011-04-10 15:11:00Z

5

Image and mask should have same size (width and height) and (most probably this is problem) type. So if it is different type you need to convert one of them so they have equal type.

edited Apr 10, 2011 at 15:11

answered Apr 10, 2011 at 14:55

Pol

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1 Comment

mobearette Over a year ago

The type is ok, the problem was in the size or the mask. I used a formula, similar to the one I used for calculating the image size, in stead of just doing this: dft_size_mask = dft_size_image;Thx :)

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