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IPCV - Image Processing and Computer Vision Toolbox for Scilab >> Filter Design and Visualization > mkfftfilter

mkfftfilter

Create frequency domain filter

Syntax

h = mkfftfilter(image,name,rc1,rc2)

Parameters

image :

Source Image

name :

Filter name, a string, the name can be 'binary', 'butterworth1', 'butterworth2', 'exp', 'gauss', or 'trapeze'

rc1 :

1st cut-off frequencies which set the filter characteristics, which is normalized to 0-1

rc2 :

2nd cut-off frequencies which set the filter characteristics, which is normalized to 0-1

h :

A matrix with values between 0 and 1. These values can then be applied on the fft spectrum of an image.

Description

This function gives some popular filters to be applied on the spectrum (fft) of an image. The Fourier Transform gives informations about which frequencies are present in a signal (spectrum). A great property of the spectrum is that the original image can be reconstructed from it. Of course, modifications in the spectrum will result in a modified image, but spectrum modifications can be easier and more intuitive. A combination of several filters is possible. All these filters are cylindrical and act only on amplitude (not on phase).

Examples

S = imread(fullpath(getIPCVpath() + "/images/measure_gray.jpg"));
h = mkfftfilter(S,'gauss',0.1);
S2 = fft2(im2double(S));
S3 = S2.*fftshift(h);
S4 = real(ifft(S3));
imshow(S4);

See also

Authors

Bibliography

1. "Optique: fondements et applications" J-P PEREZ 6e edition, Dunod

2. chap34: introduction au traitement numerique des images et a la couleur


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