Help with "ColorYUV" gamma in avisyth

[zanzar]

there is a video where i lowered the gamma because it looks better that way

"ColorYUV(cont_y=-7, cont_u=0, cont_v=10,gamma_y=-60)'

the only problem is that blacks turn into too black resulting in some detail loss on black areas (anime)
lets say black gloves for example become just charcoal

in short is there a way to crank up the gamma only for black colors?

[hello_hello]

Have you tried Levels?

(0, 1.0, 255, 0, 255, coring=false)

The zeros are the black input and output levels and the 255's are the whites, and 1.0 is the default gamma.

If you reduce the gamma and the blacks get too dark you can compensate by raising the black level a little.

(0, 1.0, 255, 8, 255, coring=false)

or maybe try a standard limited to fullrange levels conversion (or something in between) rather than mess with the gamma? I find stretching/reducing the luminance range is generally better than messing with the gamma on it's own.

(16, 1.0, 235, 0, 255, coring=false)

or ColorYUV(Levels="TV->PC")

or try YLevels(). It's very much like the Avisynth Levels function but I think it adjusts chroma too (sometimes that's better, and sometimes not, so it pays to compare the two). http://avisynth.nl/index.php/Ylevels

[raffriff42]

There's SGradation, which can be use in combination with gamma, brightness and contrast.
It's a kind of "second-order gamma"

#    output luma with gamma < 1.0
#               ^
#            255+                           +
#               |                           +
#               |                          +
#               |                         +
#               |                       +
#               |                     +
#               |                  +
#            128+            +++
#               |        +
#               |     +
#               |   +
#               | +
#               |+
#               |+
#              0+-------------+-------------+> input luma
#               0            128           255

(EDIT YLevels.avsi::YLevelsS does something very similar)

[jagabo]

This will prevent darks from dropping below Y=16:

ColorYUV(levels="TV->PC").ColorYUV(cont_y=-7, cont_u=0, cont_v=10,gamma_y=-60).ColorYUV(levels="PC->TV")

You may have to adjust the values a little.