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Image: DCT filter comparison

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Description: This image shows the effect of applying eight different filters on a test image by multiplying the spectra obtained with discrete cosine transform (DCT). Common effect such as low-pass and high-pass can be seen. I created the image completely myself, using my own photo and Aileron font (CC0, by dot colon) and I release it under CC0. I used GIMP and GNU Octave. The Octave command used to filter the image is (consider CC0 as well): pkg load signal; for i = 1:24, img = uint8(idct2(dct2(double(rgb2gray(imread("~/Documents/fft dct examples/test.png")))) .* rgb2gray(double(imread(strcat("~/Documents/fft dct examples/filter",num2str(i),".png")))))); imwrite(img,strcat("~/Documents/fft dct examples/result",num2str(i),".png")); end The spectrum image is displayed directly without any smart mapping with: imshow(uint8(dct2(rgb2gray(imread("~/Documents/fft dct examples/test.png"))))) Therefore the values are cropped and the spectrum image loses some information about the original image. It is there only to give an idea about what the spectrum looks like.
Title: DCT filter comparison
Credit: Own work
Author: Drummyfish
Usage Terms: Creative Commons Zero, Public Domain Dedication
License: CC0
License Link: http://creativecommons.org/publicdomain/zero/1.0/deed.en
Attribution Required?: No

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