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+.Dd January 19 2008
+.Dt PNMCURVE 1
+.Os
+.Sh NAME
+.Nm pnmcurve
+.Nd apply tone curves to pnm images
+.Sh SYNOPSIS
+.Nm
+.Op Fl r 
+.Op Fl g
+.Op Fl b
+.Op Fl c Ar curve
+.Sh DESCRIPTION
+.Nm
+applies tone curves to pnm images.
+Curves are specified as a set of control points of a cubic spline.
+.Nm
+applies the resulting spline curve to the pnm image read
+from stdin and writes the resulting image to stdout.
+Command line switches allow to apply the curve only to
+selected color channels.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl r
+Apply curve to red channel.
+.It Fl g
+Apply curve to green channel.
+.It Fl b
+Apply curve to blue channel.
+.It Fl c
+Curve to apply. 
+Curves must be of the form
+x1:y1,x2:y2,x3:y3 where xi:yi are
+control points of a cubic spline curve.
+xi, yi must be in the range [0.0,1.0].
+.El
+.Sh EXIT STATUS
+.Ex -std
+.Sh EXAMPLES
+.Dl "pnmcurve -c 0.0:0.0,0.5:0.2,1.0:1.0 < test.pnm > darker.pnm"
+.Pp
+.Sh SEE ALSO
+pnm(5)
+.Sh AUTHOR
+Johannes Hofmann <Johannes.Hofmann@gmx.de>