FFT adaptive lowpass filter.

 

function call:

[out_img1r,out_img1i]=vsg('FFTAdaptiveLP',in_img1r,in_img1i,thresh);

 

Arguments:

in_img1r - input image, 3 channel RGB, 1 channel greyscale or binary image of the real FFT coefficients.

in_img1i - input image, 3 channel RGB, 1 channel greyscale or binary image of the imaginary FFT coefficients.

Thresh – a double which specifies a magnitude threshold, above which all input image values will be kept. Below this value will have output pixels set to 0.

 

Description:

The user defined input limit is the cutoff frequency for the filter. Unlike the low-pass filter which is based on the position of the filter in Fourier space, this approach is dependent on the real and imaginary values of all the data in the Fourier space.

out_img1r – the output image values are the real FFT coefficients of the input images, which have had a threshold applied to their values.

out_img1i – the output image values are the imaginary FFT coefficients of the input images, which have had a threshold applied to their values.

 

Example:

img = openimage('baboon.jpg');

[out_img1]=vsg('GreyScaler',img);

figure;image(uint8(out_img1));

[out_img1,out_img2]=vsg('FFT',out_img1);

[out_img1r,out_img1i]=vsg('FFTAdaptiveLP',out_img1,out_img2,0.3);

[out_img1]=vsg('InvFFT',out_img1r,out_img1i);

h=figure;image(uint8(out_img1));set(h,'Name','FFTAdaptiveLP');

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