ff-blur.1

.Dd 2024-03-29
.Dt FF-BLUR 1
.Os farbfeld-utils
.Sh NAME
.Nm ff-blur
.Nd farbfeld filter that applies Gaussian blur to the input picture
.Sh SYNOPSIS
.Nm
<kernel size> <standard deviation>
.Sh DESCRIPTION
.Nm
reads a
.Xr farbfeld 5
image from stdin, applies Gaussian blur and writes the result to stdout.
.Pp
Tip: use
.Xr ff-border 1
to add a border if you want the output of the Gaussian blur to be the same size as the input.
.Pp
In case of an error
.Nm
writes a diagnostic message to stderr.
.Sh EXIT STATUS
.Bl -tag -width Ds
.It 0
Image processed successfully.
.It 1
An error occurred.
.El
.Sh OPTIONS
The filter takes two arguments, which are the kernel size (a positive
integer), and the standard deviation (a nonzero real number).

The kernel size is the amount that each edge of the picture is cropped, as
well as setting the filter quality; larger numbers will result better quality
filter.

If the standard deviation is x, then the recommended kernel size is (3x+1),
rounded up.
.Sh EXAMPLES
$
.Nm
9 2.399 < image.ff > image-blur.ff
.Sh SEE ALSO
.Xr ff-border 1 ,
.Xr farbfeld 5 ,
.Xr farbfeld-utils 7