diff --git a/doc/filters.texi b/doc/filters.texi
index 3108ad349e..604e44d569 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -14736,6 +14736,12 @@ Xmap and Ymap input video streams must be of same dimensions. Output video strea
 will have Xmap/Ymap video stream dimensions.
 Xmap and Ymap input video streams are 16bit depth, single channel.
 
+@table @option
+@item format
+Specify pixel format of output from this filter. Can be @code{color} or @code{gray}.
+Default is @code{color}.
+@end table
+
 @section removegrain
 
 The removegrain filter is a spatial denoiser for progressive video.