Filter effects in FMX. What are the units of BlurAmount?

  

I’m creating a vector graphics application and would like to include filters. I’m using the Shader Filters sample application as reference. My app supports SVG export, so any filters I support in the app must also be supported in SVG (so that they look the same in SVG and FMX as closely as possible). Of course I don’t expect to find matching SVG filters for all FMX filters.
The BlurAmount parameter is common to several filters such as GaussianBlur, DirectionalBlur, Glow, etc. I’d like to know what the units of BlurAmount actually are for each filter? This would be useful for several reasons. When exporting to SVG with GaussianBlur for example I need to convert BlurAmount to standard deviation. It would also be useful for working out the amount of padding needed around each drawn object so that the filtered object doesn’t extend beyond the size of the bitmap. Different filters seem to have different units for BlurAmount. For example DirectionalBlur produces much less blurring than GaussianBlur with the same BlurAmount value. The documentation for each filter doesn’t mention what the units are.
http://docwiki.embarcadero.com/Libraries/Sydney/en/FMX.Filter.Effects.TGaussianBlurEffect.BlurAmount

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