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Bruce Murray Space Image Library

Example of "denoising" of Cassini radar images of Titan

Example of "denoising" of Cassini radar images of Titan
Example of "denoising" of Cassini radar images of Titan Cassini's radar images of Titan reveal far more details on the surface than are visible in optical camera photos. But they suffer from a lot of "noise," a salt-and-pepper appearance of random variation among pixel values. At the 2012 Lunar and Planetary Science Conference, Antoine Lucas and Oded Aharonson presented the results of their work "denoising" these data, producing beautiful, crisp images that reveal fine details of Titan's surface. Courtesy Antoine Lucas, Oded Aharonson

On the left is an example radar image (a). Below (b) is a denoised version. The image in (c) shows the residual, basically what was removed from (a) to produce (b). If the process really has only removed noise and not artificially brightened certain areas, the residual should look totally random. I do see hints of structure in the residual here and there, but not along the skinnier channels, which is a good thing. The most prominent structure in the residual is a horizontal band that is an artifact of the process by which the radar image was produced in the first place, so it's actually good to see that band removed from the image. On the right in (d) and (e) are a detail view of the image, showing fine structures of river channels made more visible in the denoised version.