Hi SAR users,
We are happy to announce that Sentinel Hub now offers the Lee speckle filter for your use! For the Lee filter, window sizes up to 7x7 are supported.
In general, radar produces noisy (speckled) imagery and for many use-cases, speckle filters which reduce this noise are useful to essential. Land classification is one example. Speckle filters are moving window filters which modify the central pixel value based on all the pixel values in the window. As pixel values are changed, speckle filtering is therefore optional and its use and settings depend on your use-case. Note also that one consequence of moving windows is that the processing time increases as window size increases.
In particular, the effect of the Lee filter depends on the resolution/zoom level; it is most pronounced at native resolution and gets reduced as you zoom out. We therefore suggest you use it at or near native resolution and switch it off at low(er) resolution to save processing time. The effect of the filter is negligible if greatly zoomed out.
For more information about how to use the Lee filter, see the docs here: https://docs.sentinel-hub.com/api/latest/data/sentinel-1-grd/#speckle-filtering
The following example illustrates a Lee 5x5 filtered image vs an unfiltered one:
