From d5f187fd3355ec6d4922d8479930c10d1b6f9ebf Mon Sep 17 00:00:00 2001 From: Nolan L Date: Sun, 12 Dec 2010 17:59:10 +0000 Subject: Add gradfun filter, ported from MPlayer. Patch by Nolan L nol888 <=> gmail >=< com. See thread: Subject: [FFmpeg-devel] [PATCH] Port gradfun to libavfilter (GCI) Date: Mon, 29 Nov 2010 07:18:14 -0500 Originally committed as revision 25942 to svn://svn.ffmpeg.org/ffmpeg/trunk --- doc/filters.texi | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'doc/filters.texi') 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. -- cgit v1.2.3