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Diffstat (limited to 'doc/filters.texi')
-rw-r--r-- | doc/filters.texi | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/doc/filters.texi b/doc/filters.texi index c460aa951f..be3f8e180e 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -425,6 +425,35 @@ frei0r=perspective:0.2/0.2:0.8/0.2 For more information see: @url{http://piksel.org/frei0r} +@section gradfun + +Fix the banding artifacts that are sometimes introduced into nearly flat +regions by truncation to 8bit colordepth. +Interpolate the gradients that should go where the bands are, and +dither them. + +The filter takes two optional parameters, separated by ':': +@var{strength}:@var{radius} + +@var{strength} is the maximum amount by which the filter will change +any one pixel. Also the threshold for detecting nearly flat +regions. Acceptable values range from .51 to 255, default value is +1.2, out-of-range values will be clipped to the valid range. + +@var{radius} is the neighborhood to fit the gradient to. A larger +radius makes for smoother gradients, but also prevents the filter from +modifying the pixels near detailed regions. Acceptable values are +8-32, default value is 16, out-of-range values will be clipped to the +valid range. + +@example +# default parameters +gradfun=1.2:16 + +# omitting radius +gradfun=1.2 +@end example + @section hflip Flip the input video horizontally. |