MATLAB: What is the time complexity

digital image processingfft2time complexity

if i will depend on fft2 for calculating weighted mean and variance of image and i will do that several times with a for loop, what will be the time complexity?? will it be O(kNlog_2(N)) where N is the image size and k is the no of times of for loop ??

Best Answer

O(k*N^2*log2(N))

for square matrices.

http://fourier.eng.hmc.edu/e101/lectures/Image_Processing/node6.html and look for "Matrix Form of 2D DFT"

Related Solutions

MATLAB: IMAGE Processing with FFT

For example:

N = 20;             %steps
FFT1 = fft2(Image1);
FFT2 = fft2(Image2);
delta = (FFT2 - FFT1) ./ N;
for K = 0 : N
  IM3 = ifft(FFT1 + K * delta);
  image(real(IM3));
  pause(2);
end

MATLAB: How to properly measure computational complexity (run-time) in Matlab

In order to get an experimental feel for computational complexity, you need to run the code with several different sizes of problems, and model how the time increases as the size of the problem increases.

Keep in mind that computational complexity is insensitive to constant multipliers or constant additions. Something that takes (say) always 100000 times longer, would be considered the same complexity.

Best Answer

Related Solutions

MATLAB: IMAGE Processing with FFT

MATLAB: How to properly measure computational complexity (run-time) in Matlab

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