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ALE
Image Processing Software Deblurring, Anti-aliasing, and Superresolution. Local Operation localhost 5393119533 |
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ALE versions 0.4.1 and later implement a drizzling algorithm based on that outlined in research by Richard Hook and Andrew Fruchter.1
In the drizzle rendering method, pixels from source images are considered to span an area smaller than the original source pixel (a 'reduced footprint'); these source images with reduced pixel footprint are transformed for alignment, and the reduced-area pixels from all transformed source images are combined to form the target image, where each source pixel contributes to each target pixel linearly with the area of overlap after transformation.
ALE uses an approximation to the above approach, wherein the area of overlap is calculated in the coordinates of the source image and then multiplied by a factor approximating any difference in scale between the source and target images; for the purpose of these calculations, the region of the target pixel is approximated by a rectangle in the source coordinate system having all sides parallel to the source image coordinate axes.
Assuming small drizzling radius, drizzling is approximately the same as convolution of discrete pixel data with a box filter having the same radius as the chosen drizzling radius. For a very large, uniform input sequence, point sampling with simple optics, and sufficiently small radius, drizzling should provide an acceptable approximation of T.
1 More information on drizzling can be found in the paper by Hook and Fruchter, "Variable-Pixel Linear Combination", published in vol. 125 of the ASP Conference Series (eds. Gareth Hunt and H. E. Payne). This paper was also published on-line at:
http://www.cv.nrao.edu/adass/adassVI/hookr.html
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