LDCALIB

Name

ldcalib

Purpose

Load calibration frames and information as instructed by calib file.

Description

Calling Sequence

ldcalib,calibfile,calib,valid

Inputs

calibfile - Name of calibration file to read.

Optional Input Parameters

Keyword Input Parameters

CALIBPATH - Optional path to the calibration information directory.
Default is the current directory.
EMPTY - Don't look for or load files.cal. Instead, create a calib
structure with "empty" values. The empty values depend on
the field but should work with programs requiring this
structure. The empty values will ensure that nothing would
be done in "calibrating" an image.

Outputs

calib - anonymous structure with calibration information
tag contents and usage:
cxsize - Xsize of calibration frames (unknown if -1)
cysize - Ysize of calibration frames (unknown if -1)
xl - overscan left boundary (-1 means no overscan).
xr - overscan right boundary (-1 means no overscan).
x1 - LLHC (x) of cropping region.
x2 - URHC (x) of cropping region.
y1 - LLHC (y) of cropping region.
y2 - URHC (y) of cropping region.
bias - Bias image.
dark - dark image (scalar 0 if no dark correction needed).
flat - Array of flat images.
frngarr- Array of fringe correction images.
frngptr- Array of pointers into frngarr for each filter.
filter - String array of filter names for flat array.
valid - Flag, if true indicates a valid calibration set was loaded. The
contents of calib are unreliable if this flag is false.

Keyword Output Parameters

Common Blocks

Side Effects

Restrictions

Procedure

This program reads the given calibration file, decodes the information into
a structure with all the was in the file. It handles reading all the
supported version of calibration files with the hope that all older
versions can always be read and made (in some way) to be upward
compatible. The organization of the returned structure is, however,
subject to future change and expansion as the need arises.
The following describe the file format for the supported versions.
Version 1 files:
Line 1 - ID line, "calib_file_v01"
Line 2 - Instrument (rest of file depends on this).
LCCD
Line 3 - Name, including path, of bias frame.
Line 4 to end - Filter code, and file name of flat field
image for this filter.
LORAL
Line 3 - overscan limits (x1, x2)
Line 4 - cropping region (x1:x2,y1:y2)
Line 5 - Name, including path, of bias frame.
Line 6 to end - Filter code, and file name of flat field
image for this filter.
Version 2 files:
Line 1 - ID line, calib_file_v02
Line 2 - overscan limits (x2,x2), if none, use -1 -1
Line 3 - cropping region (x1:x2,y1:y2)
Line 4 - Name, including path, of bias frame.
Line 5 to end - Filter code, and file name of flat field
image for this filter.
Version 3 files:
Line 1 - ID line, calib_file_v03
Line 2 - overscan limits (x2,x2), if none, use -1 -1
Line 3 - cropping region (x1:x2,y1:y2)
Line 4 - Name, including path, of bias frame.
Line 5 - Name, including path, of dark frame. [none] means not needed.
Line 6 to end - Filter code, and file name of flat field
image for this filter plus optional fringe
correction image.

Modification History

95/08/08, Written by Marc W. Buie, Lowell Observatory
99/05/16, MWB, Added support for optional fringe correction image(s).
99/05/20, MWB, near total rewrite to legitimize this routine for
inclusion in ccdphot.pro. Numerous changes were made
that change the contents of the calibration structure
but make it more general as is needed by ccdphot.
99/10/28, MWB, fixed cxsize,cysize bug
99/11/15, MWB, added EMPTY keyword
2000/10/12, MWB, fixed bug that caused crash when loading a file that
did not have any flat field frame information.
2001/05/01, MWB, changed behavior so that if x1,x2 or y1,y2 make it to the
end, then these values are loaded from the cxsize or cysize.
2010/04/22, MWB, changed to ignore blank lines in the filter section.
2010/11/17, MWB, added silent keyword