Êtes-vous un étudiant de l'EPFL à la recherche d'un projet de semestre?
Travaillez avec nous sur des projets en science des données et en visualisation, et déployez votre projet sous forme d'application sur Graph Search.
Concept
Redimensionnement d'image
Résumé
In computer graphics and digital imaging, image scaling refers to the resizing of a digital image. In video technology, the magnification of digital material is known as upscaling or resolution enhancement.
When scaling a vector graphic image, the graphic primitives that make up the image can be scaled using geometric transformations, with no loss of . When scaling a raster graphics image, a new image with a higher or lower number of pixels must be generated. In the case of decreasing the pixel number (scaling down) this usually results in a visible quality loss. From the standpoint of digital signal processing, the scaling of raster graphics is a two-dimensional example of sample-rate conversion, the conversion of a discrete signal from a sampling rate (in this case the local sampling rate) to another.
Image scaling can be interpreted as a form of image resampling or image reconstruction from the view of the Nyquist sampling theorem. According to the theorem, downsampling to a smaller image from a higher-resolution original can only be carried out after applying a suitable 2D anti-aliasing filter to prevent aliasing artifacts. The image is reduced to the information that can be carried by the smaller image.
In the case of up sampling, a reconstruction filter takes the place of the anti-aliasing filter.
File:160 by 160 thumbnail of 'Green Sea Shell'.png | Original 160x160px image
File:160 by 160 thumbnail of 'Green Sea Shell' - 0. in fourier domain.png | Original image in spatial-frequency domain
File:160 by 160 thumbnail of 'Green Sea Shell' - 1. fourier filtered for downsampling to 40 x 40.png | 2D [[low-pass filter]]ed, but still at 160x160px
File:160 by 160 thumbnail of 'Green Sea Shell' - 1.1. fourier filtered image for downsampling to 40 x 40 in fourier domain.png | [[Filter (signal processing)|Filtered]] image in spatial-frequency domain
File:160 by 160 thumbnail of 'Green Sea Shell' - 2. downsampling to 40 x 40 (nearest neighour).png | low-pass filtered 160x160px image 4× downsampled to 40x40px{{nbsp}}
File:160 by 160 thumbnail of 'Green Sea Shell' - 3.
Source officielle
À propos de ce résultat
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.