File:DCT filter comparison.png

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Original file ‎(538 × 709 pixels, file size: 258 KB, MIME type: image/png)

Summary

Description
English: 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.
Date
Source Own work
Author Drummyfish

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
Creative Commons CC-Zero This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.

Captions

comparison of diference DCT filter effects

Items portrayed in this file

depicts

inception

27 March 2019

File history

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Date/TimeThumbnailDimensionsUserComment
current15:40, 28 March 2019Thumbnail for version as of 15:40, 28 March 2019538 × 709 (258 KB)DrummyfishChange some filters for more demonstrative results.
22:02, 27 March 2019Thumbnail for version as of 22:02, 27 March 2019538 × 709 (261 KB)DrummyfishUser created page with UploadWizard
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