Image Filtering: Difference between revisions
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Filtering an image refers to sampling an image in a way that resolve aliasing. | Filtering an image refers to sampling an image in a way that resolve aliasing. | ||
Since images are a 2D signal, image filtering is a type of [[Wikipedia: Filter (signal processing) signal filtering]. | Since images are a 2D signal, image filtering is a type of [[Wikipedia: Filter (signal processing) | signal filtering]]. | ||
==Denoising== | ==Denoising== | ||
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{{ main | Wikipedia: Bilateral filtering }} | {{ main | Wikipedia: Bilateral filtering }} | ||
A bilateral filter is a gaussian filter but pixels are additionally weighted by the gaussian of the intensity difference. Hence, edges are preserved since adjacent pixels which have significantly different intensity are weighted much less. | A bilateral filter is a gaussian filter but pixels are additionally weighted by the gaussian of the intensity difference. Hence, edges are preserved since adjacent pixels which have significantly different intensity are weighted much less. | ||
This can be used for upsampling lower resolution depth maps or tone maps using [https://johanneskopf.de/publications/jbu/paper/FinalPaper_0185.pdf joint bilateral upscaling]. E.g. if you have a low-resolution image, low-resolution depth, and a high-resolution reference, you can upscale the depth while keeping the edges from the high-resolution reference. | |||
==Upfiltering== | ==Upfiltering== | ||