1
% @(#)illflaccd.hlq 19.1 (ESO-IPG) 02/25/03 14:15:01
2
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3
%.COPYRIGHT (c) 1993 European Southern Observatory
6
%.KEYWORDS MIDAS, ccd package, SKYFLAT/CCD
7
%.PURPOSE On-line help file for the command: SKYFLAT/CCD
8
%.VERSION 930827 RHW Documentation created
9
%.VERSION 930922 RHW Improved documentation
10
%.VERSION 931101 RHW Released
11
%---------------------------------------------------------------------
15
ILLFLAT/CCD 1-Nov-1993 RHW
17
ILLFLAT/CCD [in_spec] [out_frm] [xboxmn,xboxmx] [yboxmn,yboxmx] [clip]
19
Apply correction to a flat field to remove illumination pattern
22
Apply correction to flat field to remove illumination pattern
25
ILLFLAT/CCD [in_spec] [out_frm] [xboxmn,xboxmx] [yboxmn,yboxmx]
26
[clip] [lowsig,higsig]
28
in_spec = single flat frame or MIDAS CCD reduction table (with the
29
extension .tbl) containing the names of the flat frame(s)
30
in the column :FF. Default input is taken from the keyword
33
out_frm = name of the illumination corrected flat field. Default
34
the output file the same as the input frame: hence by
35
default the input flat frame will be OVERWRITTEN.
36
This parameter is only used is case of single frame input
37
for the first parameter. In case the output is taken a
38
reduction table the output frame(s) will replace the input
39
flat frames: hence the input flat frame will be OVERWRITTEN.
41
xboxmn,xboxmx = minimum and maximum smoothing box size along the x
42
axes. The minimum box size is used at the edges and grows
43
to the maximum size in the middle of the image. This
44
allows the smoothed image to better represent gradients
45
at the edge of the image. If a size is less then 1 it is
46
interpreted as a fraction of the image size. If a size is
47
greater than or equal to 1 then it is the box size in
48
pixels. A size greater than the size of image selects a
49
box equal to the size of the image. Default values are taken
50
from the keyword IL_XBOX.
52
yboxmn,yboxmx = see above. Default values are taken from IL_YBOX.
54
clip = Clean the input frame(s) of objects? If yes then a clipping
55
algorithm is used to detect and exclude objects from the
56
smoothing. Defaault taken from IL_CLIP.
58
lowsig,higgsig = sigma clipping thresholds above and below the
59
smoothed illumination. Default values are taken from
60
the keyword IL_SIGMA. The keyword is only read in case
64
The command operates very similar to the command REDUCE/CCD, which
65
the exception that the command not check for the exposure type of
68
In case the input is an association table the command will check for
69
the existence of the flat frames in the column :FF in the association
70
table. Flat frames that do not exit will be created first, provided
71
the association table contain the :FF column. Other relevant
72
calibration frames for processing the flat frames, will be taken from
73
the corresponding calibration columns. From the reduced flat field,
74
an illumination correction frame is produced by smoothing the
75
calibrated flat frame using a moving "boxcar" average.\\
77
The reduced flat frame is then divided by the scaled illumination
78
correction to produce the illumination corrected flat. The output
79
will OVERWRITE the original (reduced) flat frames. Hence, the output
80
illumination flat will automatically be used as flat in subsequent
81
calibration procedure(s).\\
82
NOTE: THE MASTER FLAT FIELDS WILL BE SUBSTITUTED BY THE CORRECTED ONES.
84
In the case of single frame input and all calibration frames input
85
will be taken from the SC_ keywords and must exist. Also here, the
86
default is that the output illumination corrected flat will replace
89
The IM_SEC keyword may be used to assign a region of interest for which
90
the correction has to be done.\\
92
For more information see the CCD chapter in Volume B of the User's
96
SET/CCD, SHOW/CCD, HELP/CCD, REDUCE/CCD, SKYCOR/CCD
100
ILLFLAT/CCD redtbl.tbl
101
Reduce all flat frames in the the ccd reduction table redtbl.tbl. All
102
master calibration frames will be obtained from that reduction table.
103
Do the calibration according to the keyword settings. After calibration
104
produce an illumination frame, using the `IL_' keyword settings.
105
Hereafter the illumination corrected flat field is computed by dividing
106
the original flat by the illumination frame. All calibration frames are
107
taken from the table redtbl.tbl. The output corrected flats will have
108
the same name as the original flat except for the extension `_if'.
110
ILLFLAT/CCD m100rraw_ff m100rraw_if
111
Do the illumination correction for the frame m100rraw_ff. Check if the
112
input was already reduced, and do the reduction if needed. Hereafter
113
produce the output output frame m100rraw_if. In case calibration frames
114
are to be applied the names of these frames will be obtained from the
115
keyword SC_xxFRM and SC_xxFRM, where `xx stands for the exposure type
116
of the calibration frame (BS, DK).