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doc/filters: extend/fix documentation for the geq filter

This commit is contained in:
Stefano Sabatini 2013-05-19 22:54:27 +02:00
parent fbba76e89d
commit 281fc4e958
1 changed files with 24 additions and 12 deletions
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36
doc/filters.texi
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@ -4004,25 +4004,31 @@ The filter accepts the following options:
@table @option
@item lum_expr
the luminance expression
Set the luminance expression.
@item cb_expr
the chrominance blue expression
Set the chrominance blue expression.
@item cr_expr
the chrominance red expression
Set the chrominance red expression.
@item alpha_expr
the alpha expression
Set the alpha expression.
@item r
the red expression
Set the red expression.
@item g
the green expression
Set the green expression.
@item b
the blue expression
Set the blue expression.
@end table
The colorspace is selected according to the specified options. If
one of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
options is specified, the filter will automatically select a YCbCr
colorspace. If one of the @option{r}, @option{g}, or @option{b}
options is specified, it will select an RGB colorspace.
If one of the chrominance expression is not defined, it falls back on the other
one. If no alpha expression is specified it will evaluate to opaque value.
If none of chrominance expressions are
specified, they will evaluate the luminance expression.
If none of chrominance expressions are specified, they will evaluate
to the luminance expression.
The expressions can use the following variables and functions:
@ -4058,15 +4064,21 @@ plane.
@item cb(x, y)
Return the value of the pixel at location (@var{x},@var{y}) of the
blue-difference chroma plane. Returns 0 if there is no such plane.
blue-difference chroma plane. Return 0 if there is no such plane.
@item cr(x, y)
Return the value of the pixel at location (@var{x},@var{y}) of the
red-difference chroma plane. Returns 0 if there is no such plane.
red-difference chroma plane. Return 0 if there is no such plane.
@item r(x, y)
@item g(x, y)
@item b(x, y)
Return the value of the pixel at location (@var{x},@var{y}) of the
red/green/blue component. Return 0 if there is no such component.
@item alpha(x, y)
Return the value of the pixel at location (@var{x},@var{y}) of the alpha
plane. Returns 0 if there is no such plane.
plane. Return 0 if there is no such plane.
@end table
For functions, if @var{x} and @var{y} are outside the area, the value will be