File:Gibbs Ringing in Shepp Logan phantom.png
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Captions
Captions
Example of Gibbs ringing on edges in a Shepp-Logan phantom
Summary edit
| Description |
English: Left: Artifact free image. Right: Image with Gibbs ringing artefact, most prominent at the edge between white ring-like structure and gray internal area.
Deutsch: Links: Artefakt freies Bild. Rechts: Bild mit Kantenoszillationen (Gibbssches Phänomen), besonders Auffallend an der Kante zwischen der weißen Ring-artigen Struktur und dem grauen Innenbereich |
| Date | |
| Source | Own work |
| Author | FbrG |
Licensing edit
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MATLAB Code edit
Nh = 1024;
Nl = 256;
% high resolution phantom
hRes = phantom(Nh);
% Fourier transform
hRes_f = fftshift(fftn(fftshift(hRes)));
% take central part of kSpace to simulate low resolution
% acquisition.
mRes_f = hRes_f(Nh/2+1-Nl/2:Nh/2+1+Nl/2-1, Nh/2+1-Nl/2:Nh/2+1+Nl/2-1);
% retrieve low resolution image
mRes = 1/(Nh/Nl)^2 * abs(ifftshift(ifftn(ifftshift(mRes_f))));
% make images same size
img = cat(2, imresize(hRes, [Nl Nl]), mRes/max(mRes(:)));
% resize image
img = repelem(img, 4, 4, 3);
% save as *.png to avoid any additional compression artefacts
imwrite(img, 'Gibbs Ringing in Shepp Logan phantom.png');
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 13:03, 3 January 2021 | | 2,048 × 1,024 (74 KB) | FbrG (talk | contribs) | Uploaded own work with UploadWizard |
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