.ds Vn 1.12
.TH vinvert 1Vi "24 April 1993" "Vista Version \*(Vn"
.SH NAME
vinvert \- invert image pixel values
.SH SYNOPSIS
\fBvinvert\fR [\fIoption\fR ...] [\fIinfile\fR] [\fIoutfile\fR]
.SH DESCRIPTION
\fBvinvert\fP inverts each input image to produce a corresponding output 
image. The operation is suitable for swapping black and white in a 
grey-scale image. 
.PP
Each output pixel is computed from the corresponding input pixel by
.PP
.RS
\fIout-pixel\fP = \fIM\fP - \fIin-pixel\fP
.RE
.PP
where \fIM\fP is the maximum value allowed by the pixel representation, or 
1 in the case of \fBfloat\fP or \fBdouble\fP pixels. Input pixel values 
must lie in the range [0,\fIM\fP]. 
.PP
Each output image has the same number of bands, rows and columns, and the
same pixel representation, as the corresponding input image.
.SH "COMMAND LINE OPTIONS"
\fBvinvert\fP accepts the following options:
.IP \fB-help\fP 15n
Prints a message describing options.
.IP "\fB-in\fP \fIinfile\fP"
Specifies a Vista data file containing the input images.
.IP "\fB-out\fP \fIoutfile\fP"
Specifies where to write the output images as a Vista data file.
.PP
Input and output files can be specified on the command line or allowed to
default to the standard input and output streams.
.SH "SEE ALSO"
.na
.nh
.BR vnegate (1Vi),
.BR vop (1Vi),
.BR VImage (3Vi),
.BR Vista (7Vi)
.hy
.ad
.SH AUTHOR
Art Pope <pope@cs.ubc.ca>