.help flatten Sep84 noao.imred.generic
.ih
NAME
flatten -- Flatten images by dividing by a flat field
.ih
USAGE	
flatten images flatfield
.ih
PARAMETERS
.ls images
Images to be flattened.
.le
.ls flatfield
Flat field image to be divided into the images.
.le
.ls minflat = INDEF
All flat field pixels less than or equal to this value are replaced by
unit response.  If INDEF all the flat field pixels are used.
.le
.ls pixtype = "real"
The pixel datatype of the flattened image.  The null string ("") defaults
the pixel datatype to that of the original image before flattening.
The other choices are "short", "integer", "long", and "real".
.le
.ih
DESCRIPTION
Each of the \fIimages\fR is flatten by dividing by the \fIflatfield\fR
flat field image.  The flattened images replace the original images.
The pixel datatype of the flattened images is specified by the
\fIpixtype\fR.  The null string ("") leaves the datatype of the images
unchanged.  Low values in the flat field may be replaced by unit response
by specifying a \fIminflat\fR value.  All pixels in the flat field less
than or equal to \fIminflat\fR are given unit response.
.ih
EXAMPLES
To flatten a set of two dimensional images excluding pixels below
.2 in the flat field:

.nf
	cl> flatten frame* flat minflat=0.2
.fi
.endhelp
