Dear Jeronimo,
Am 05.01.21 um 14:22 schrieb Jeronimo Pellegrini:
There is "feathering", used in mask refinement, which adapts
a mask's edge to edges detected in image.
And recently, when updating the translation, I saw "feather size"
referring to the radius of the outer circle (or ellipsis) when
creating drawn masks.
But those are not exactly the same...
these are related but slightly different.
Feathering of drawn masks refers to smoothing the edges of the drawn
masks, which is completely unrelated to the edited image. Here you can
specify a length scale that determines the width of the smooth
transition from maximal opacity to zero opacity.
The mask refinement is based on a so-called guided filter, which has
many different applications in image processing. The guided filter is
used as an edge aware smoothing filter in the application of a guided
filter for mask refinement. This was called "matting" or "guided
feathering" by the inventors of this algorithm, see
http://kaiminghe.com/publications/eccv10guidedfilter.pdf page 12.
Therefore, the two parameters are called "feathering guide" and
"feathering radius" in the blending UI. Mask refinement is similar to
the feathering of drawn masks in the sense that "feathering radius"
determines the lengths scale over which the mask is smoothed. (More
precisely, it determines the size of the filter kernel in number of
pixels.) The only (but key) difference is that smoothing is guided by
the processed image.
It might be valuable if we could find an alternative better(!) wording
for "feathering guide" and "feathering radius" to avoid possible
confusion.
"Feathering amount" has been suggested as an alternative here. Which
is, however, not a good alternative as "amount" is rather imprecise.
This term obfuscates that the slider value determines the maximal
spatial distance that an image pixel can have such that is value may
affect the smoothing of a mask pixel at another position. I.e., if you
push the slider to 250, then the smoothing of the mask at (x, y) is
affected by all pixels within the square [x - 250, x + 250] x [y - 250,
y + 250].
By the way: There is no good direct translation of "feathering" into
German. (At least, I do not know any.) Thus, the German translation of
* "feathering guide" is "Maske anpassen mit", which means literally
(more or less) "mask adjustment by", and of
* "feathering radius" is "Anpassungsradius", which means literally (more
or less) "adjustment radius".
I hope this helps to find a good translation.
Heiko
--
-- Number Crunch Blog @ https://www.numbercrunch.de
-- Cluster Computing @ https://www.clustercomputing.de
-- Social Networking @ https://www.researchgate.net/profile/Heiko_Bauke
___________________________________________________________________________
darktable developer mailing list
to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
