From 9c9aec33c0cf5789962e2dfa0a1db619d522c61c Mon Sep 17 00:00:00 2001 From: Lou Logan Date: Mon, 15 Sep 2014 18:07:09 -0800 Subject: [PATCH] doc/filters: add geq gradient examples MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Radial gradient by Víctor Paesa. Linear gradient by Paul Gentemann. Also-by: Víctor Paesa Also-by: Paul Gentemann Signed-off-by: Lou Logan --- doc/filters.texi | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/doc/filters.texi b/doc/filters.texi index e9dab4713b..02bb34ed9e 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -5144,6 +5144,22 @@ Modify RGB components depending on pixel position: @example geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)' @end example + +@item +Create a radial gradient that is the same size as the input (also see +the @ref{vignette} filter): +@example +geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray +@end example + +@item +Create a linear gradient to use as a mask for another filter, then +compose with @ref{overlay}. In this example the video will gradually +become more blurry from the top to the bottom of the y-axis as defined +by the linear gradient: +@example +ffmpeg -i input.mp4 -filter_complex "geq=lum=255*(Y/H),format=gray[grad];[0:v]boxblur=4[blur];[blur][grad]alphamerge[alpha];[0:v][alpha]overlay" output.mp4 +@end example @end itemize @section gradfun