ff-apclut.1

.Dd 2024-03-30
.Dt FF-APCLUT 1
.Os farbfeld-utils
.Sh NAME
.Nm ff-apclut
.Nd farbfeld filter that applies a Hald CLUT picture to the input farbfeld image
.Sh SYNOPSIS
.Nm
<clut picture>
.Sh DESCRIPTION
.Nm
reads a
.Xr farbfeld 5
image from stdin, applies the applies a Hald CLUT picture and writes the result to stdout.
.Pp
A Hald CLUT is a special image that encodes how source colors should be mapped to output colors.

Any color correction can be expressed as a Color LookUp Table or CLUT (some times written as "Color
LUT").

A Hald CLUT is an image that has a specific color pattern on it. In this pattern all colors in the
color space are represented. An application that uses the HALD CLUT image to color correct an image,
takes a source image color and looks it up in the color pattern of the HALD CLUT, and the color it
finds in that place is the corrected color that should replace the source color in the destination
image. If the color doesn't exist in the CLUT, one can look up several colors and interpolate
between them.

An identity Hald CLUT is a CLUT that doesn't affect the image it is applied to. Refer to
.Xr ff-idclut 1
to generate an identity Hald CLUT. This can be changed to create a colour adjusting template that
can be applied to other pictures.
.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 only argument is a Hald CLUT picture with a precision of 8-bits per
channel (although the pixels themselves are 16-bits per channel).
.Sh REFERENCES
https://www.quelsolaar.com/technology/clut.html
.br
https://phpimagick.com/Imagick/haldClutImage?image_path=Lorikeet&hald_clut_type=EdgyEmber
.br
https://github.com/cedeber/hald-clut
.Sh EXAMPLES
$
.Nm
clut.ff < image.ff > image-adjusted.ff
.Sh SEE ALSO
.Xr ff-idclut 1 ,
.Xr farbfeld 5 ,
.Xr farbfeld-utils 7