ff-back.1

.Dd 2024-04-02
.Dt FF-BACK 1
.Os farbfeld-utils
.Sh NAME
.Nm ff-back
.Nd farbfeld filter that applies a background colour to a picture with transparent parts
.Sh SYNOPSIS
.Nm
<colour>
.Sh DESCRIPTION
.Nm
reads a
.Xr farbfeld 5
image from stdin, applies a background colour and writes the result to stdout.
.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 one argument, which is a colour without alpha. The picture is then
composed onto the background of that colour, making it fully opaque.

The colour can be defined through one of the following patterns:
   r g b             three 16-bit integer values (0 to 65535)
   rrggbb            three pairs of 8-bit hex values
   rrrrggggbbbb      three pairs of 16-bit hex values
.Sh EXAMPLES
$
.Nm
FF9090 < image.ff > image-back.ff
.Pp
$
.Nm
FF0090009000 < image.ff > image-back.ff
.Pp
$
.Nm
65280 36864 36864 < image.ff > image-back.ff
.Sh SEE ALSO
.Xr farbfeld 5 ,
.Xr farbfeld-utils 7