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.help irlincor Nov94 irred
.ih
NAME
irlincor -- Correct IR imager frames for non-linearity.
.ih
USAGE
irlincor input output
.ih
PARAMETERS
.ls input
The list of images to be corrected for non-linearity
.le
.ls output
The list of corrected output images
.le
.ls coeff1 = 1.0
The first coefficient of the correction function
.le
.ls coeff2 = 0.0
The second coefficient of the correction function
.le
.ls coeff3 = 0.0
The third coefficient of the correction function
.le
.ih
DESCRIPTION
The IR imager frames specified by \fIinput\fR, which may be a general image
template including wild cards or an @list, are corrected for non-linearity
on a pixel by pixel basis and written to \fIoutput\fR. The number of output
images must match the number input. The pixel type of the output image(s) will
match that of the input image(s), however, internally all calculations are
performed as type real. The correction is performed assuming
that the non-linearity can be represented by the following simple relationship:
.nf
ADU' = ADU * [ coeff1 + coeff2 * (ADU / 32767) + coeff3 * (ADU / 32767)**2 ]
.fi
The coefficients which occur in this expression are specified by the
parameters \fIcoeff1\fR, \fIcoeff2\fR and \fIcoeff3\fR. Their values are
derived from periodic instrumental calibrations and are believed to be
fairly constant. The default values specify a \fBnull\fR correction.
You should consult \fBJay Elias\fR for the latest values.
Note that the coefficients are expressed in terms of ADU normalised to the
maximum possible value 32767, in order that their values can be input
more easily.
.ih
EXAMPLES
1. Correct input to output using the default values for the coefficients (not a very rewarding operation!)
.nf
cl> irlincor input output
.fi
2. Correct a list of images in place using specified values for the coefficients
.nf
cl> irlincor @list @list coeff1=1.0 coeff2=0.1 coeff3=0.01
.fi
.ih
TIME REQUIREMENTS
.ih
AUTHORS
The IRLINCOR task was originally written by Steve Heathcote as part of the
CTIO package.
.ih
BUGS
The form of the correction equation is currently experimental;
a higher order polynomial or a different functional form could be accommodated
very easily if required.
It may be advisable to carry out the calculations in double precision.
.ih
SEE ALSO
onedspec.coincor, proto.imfunction
.endhelp
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