Central radius and Radius span in Diffusion and Sharpness module

Software darktable
1

I am trying to understand how to use Central radius and Radius span fields shown in D & S module. As part of that I created the table of the values set by presets. I found that all the presets related to Sharpness use the Central radius = 0 but Denoise presets adjusts both Central radius and Radius span. Note that I am interested in the presets for Denoising and Sharpness.

  1. I am trying to visualise the circles that Central radius and Radius span represent. Can i assume that Radius span refers to a one large circle and it consists of several circles who’s radius in Central radius?

  2. For sharpening are we supposed to keep Central radius at zero?

image
image696×725 69.3 KB

Thanks

1 Like
2

Its very well explained here…

Bit like the contrast eq…

The central radius selects the scale of the detail targeted and the span is like a +/- around that… so you can have a wide range or tighter…Think of the small vs larger circle when you scroll and adjust the curve in the tone eq…

2 Likes
3

Thanks I will watch.

4

He also does one in more detail…

1 Like