File:160 by 160 thumbnail of 'Green Sea Shell' - 4. fourier reconstruction from 40 x 40 (aliasing ).png

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160_by_160_thumbnail_of_'Green_Sea_Shell'_-_4._fourier_reconstruction_from_40_x_40_(aliasing_).png ‎(162 × 162 pixels, file size: 21 KB, MIME type: image/png)

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English: 160_by_160_thumbnail_of_'Green_Sea_Shell' - 3. fourierreconstruction from 40 x 40 (non-llowpass filtered one!), with serious aliasing artifacts

matlab Code: filt=zeros(160,160); filt(1:20,1:20)=1; filt(end-19:end,1:20)=1; filt(1:20,end-19:end)=1; filt(end-19:end,end-19:end)=1; x160_f(:,:,1)=ifft2(fft2(double(x160(:,:,1))).*filt); %nyquist lowpass filter x160_f(:,:,2)=ifft2(fft2(double(x160(:,:,2))).*filt); x160_f(:,:,3)=ifft2(fft2(double(x160(:,:,3))).*filt);

x160_d(:,:,1)=x160(1:4:end,1:4:end,1); %downsampling to 40x40 of the NON_NYQUIST LOWPASS FILTER IMAGE by nearest neighbour -> ALIASING x160_d(:,:,2)=x160(1:4:end,1:4:end,2); x160_d(:,:,3)=x160(1:4:end,1:4:end,3);

x160_i(:,:,1)=interpft(interpft(x160_d(:,:,1),160,1),160,2); %%reconstruction in fourierdomain to 160x160 by high freqeuncy padding x160_i(:,:,2)=interpft(interpft(x160_d(:,:,2),160,1),160,2); x160_i(:,:,3)=interpft(interpft(x160_d(:,:,3),160,1),160,2);

figure; imagesc(uint8(real(x160_i)))) % clipping/saturating to 0...255 by uint8
Date
Source File:160_by_160_thumbnail_of_'Green_Sea_Shell'.png
Author James Petts / shaddim

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Date/TimeThumbnailDimensionsUserComment
current06:02, 21 May 2022Thumbnail for version as of 06:02, 21 May 2022162 × 162 (21 KB)Phreneticc (talk | contribs)Reduced "weight" of the file.
11:33, 3 April 2016Thumbnail for version as of 11:33, 3 April 2016162 × 162 (72 KB)Shaddim (talk | contribs)User created page with UploadWizard

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