not sure i understand what you mean by upper.. to the top of the widget or
to the right (brighter colour)?
the four triangles in the slider define a curve like that:
http://www.darktable.org/usermanual/ch03s02s08.html.php#d0e4115
so you can select mid-tones, too (not only blacks and highlights).
The upper scale is especially useful to protect parts of the image which
would otherwise be pushed out of limits, for example very bright or dark
areas in case of the equalizer module.
This does not apply to input masks because of the way how the equalizer
works.
Regards,
Markus
Am 09.01.2015 um
The discussion regarding Luminosity Masks has certainly made me rethink the
way that I process many images.
One 'feature' of parametric masking that still eludes me however and that is
the use of the upper (second) adjustment scale that appears, in the light of
multiple module applications, to
