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.help text2mask Jun96 proto
.ih
NAME
text2mask -- convert text description to pixel mask
.ih
USAGE
.nf
text2mask text mask ncols nlines
.fi
.ih
PARAMETERS
.ls text
Text file of pixel regions. The format of this file consists of lines of
individual pixels (whitespace separated column and line) or rectangular
regions (whitespace separated starting and ending columns and starting and
ending lines).
.le
.ls mask
Pixel mask name to be created. A pixel list image, .pl extension,
is created so no extension is necessary.
.le
.ls ncols, nlines
Dimensions for pixel mask image.
.le
.ls linterp = 1
Mask code for rectangular regions which are narrower in the line direction
than the column direction.
.le
.ls cinterp = 2
Mask code for rectangular regions which are narrower in the column direction
than the line direction.
.le
.ls square = 3
Mask code for square regions which are larger than a single pixel.
.le
.ls pixel = 4
Mask code for single pixels.
.le
.ih
DESCRIPTION
A text file describing individual pixels or rectangular regions is
converted to a pixel mask image in pixel list format. The name of
the text file, the name of the pixel mask to be created, and the
dimensions of the pixel mask image are specified.
The text file consists of lines of two or four numbers. If two numbers
are given, separated by whitespace, they define a single pixel and
the values are the column and line pixel coordinates. If four numbers
are given, separated by whitespace, they define a rectangular region.
The four numbers are the pixel coordinates for the starting column,
the ending column, the starting line, and the ending line. This format
is the same as the old (pre-V2.11) "fixpix" format. This task may
be used to convert these old "fixpix" data files to pixel masks (as used
by the new \fBfixpix\fR task) or to create pixel masks.
The different region shapes may be coded by the mask values. This is
useful with the \fBfixpix\fR task which can select different replacement
methods based on the mask codes. In particular, one may want to interpolate
along the narrower dimension of a rectangular region. The region
shapes that may be coded are individual pixels, square regions, and
rectangular regions with narrow dimension along lines or columns.
In addition to this task,
pixel mask images may be made in a variety of ways. Any task which produces
and modifies image values may be used. Some useful tasks are
\fBimexpr, imreplace, imcopy,\fR and \fBmkpattern\fR. If a new image
is specified with the explicit ".pl" extension then the pixel mask
format is produced. Another way to make masks are with the
task \fBccdmask\fR. The task \fBccdmask\fR is specialized to make a mask
of bad pixels from flat fields or, even better, from the ratio of
two flat fields of different exposure levels.
.ih
EXAMPLES
1. Convert a text region description into a mask and then use it to
replace pixels by interpolation along the narrower dimension.
.nf
cl> list2mask fp.dat mask
cl> fixpix pix mask linterp=1,3,4 cinterp=2
.fi
.ih
REVISIONS
.ls TEXT2MASK V2.11
This task is new and appears in conjunction with a new pixel mask
based version of \fBfixpix\fR.
.le
.ih
SEE ALSO
imreplace, imexpr, imcopy, imedit, fixpix
.endhelp
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