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include <error.h>
include "sky.h"
# SKY -- Determine sky and sky sigma in an image.
#
# Get the sky and sigma map pointers. This is layered on the MAPIO routines
# and lower level sky algorithms. The sky parameter structure will be
# allocated if needed and must be freed by the calling program.
#
# If they are not defined compute an initial
# sky and/or sky sigma surface fit using a subset of the input lines.
# Whether the sky and/or the sigma are fit is determined by whether the input
# sky and sky sigma pointers are NULL. The initial data for the surface fit
# is measured at a subset of lines with any masked pixels excluded. Objects
# are removed by fitting a 1D curve to each line, rejection points with large
# residuals and iterating until only sky is left. The sky points are then
# accumulated for a 2D surface fit and the residuals are added to a
# histogram. The absolute deviations, scaled by 0.7979 to convert to an
# gausian sigma, are accumulated for a sky sigma surface fit. After all the
# sample lines are accumulated the surface fits are computed. The histogram
# of residuals is then fit by a gaussian to estimate an offset from the sky
# fit to the sky mode caused by unrejected object light. The offset is
# applied to the sky surface.
procedure sky (par, im, bpm, expmap, skyname, signame, skymap, sigmap,
dosky, dosig, logfd)
pointer par #I Parameters
pointer im #I Input image
pointer bpm #I Input mask
pointer expmap #I Exposure map
char skyname[ARB] #I Sky map name
char signame[ARB] #I Sigma map name
pointer skymap #O Sky map
pointer sigmap #O Sigma map
bool dosky #O Sky computed?
bool dosig #O Sigma computed?
int logfd #I Verbose?
real rval
pointer sp, namesky, namesig
int errcode()
pointer map_open()
errchk map_open, sky_fit, sky_block
begin
call smark (sp)
call salloc (namesky, SZ_FNAME, TY_CHAR)
call salloc (namesig, SZ_FNAME, TY_CHAR)
if (logfd != NULL)
call fprintf (logfd, " Set sky and sigma:\n")
# Check whether to compute a sky.
skymap = NULL
if (skyname[1] != EOS) {
iferr (skymap = map_open (skyname, im)) {
skymap = NULL
if (errcode() != 2)
call erract (EA_ERROR)
}
if (logfd != NULL && skymap != NULL) {
ifnoerr (call map_getr (skymap, "constant", rval)) {
call fprintf (logfd, " Use constant input sky: %g\n")
call pargr (rval)
} else {
call fprintf (logfd, " Use input sky: %s\n")
call pargstr (skyname)
}
}
}
dosky = (skymap == NULL)
# Check whether to compute a sky sigma.
sigmap = NULL
if (signame[1] != EOS) {
iferr (sigmap = map_open (signame, im)) {
sigmap = NULL
if (errcode() != 2)
call erract (EA_ERROR)
}
if (logfd != NULL && sigmap != NULL) {
ifnoerr (call map_getr (sigmap, "constant", rval)) {
call fprintf (logfd, " Use constant input sigma: %g\n")
call pargr (rval)
} else {
call fprintf (logfd, " Use input sigma: %s\n")
call pargstr (signame)
}
}
}
dosig = (sigmap == NULL)
# Compute the sky.
if (dosky || dosig) {
# Set parameters.
call sky_pars ("open", "", par)
switch (SKY_TYPE(par)) {
case SKY_FIT:
call sky_fit (SKY_SKF(par), dosky, dosig, im, bpm, expmap,
skyname, signame, skymap, sigmap, logfd)
case SKY_BLOCK:
call sky_fit (SKY_SKF(par), dosky, dosig, im, bpm, expmap,
"", "", skymap, sigmap, logfd)
call map_seti (skymap, "sample", 5)
call map_seti (sigmap, "sample", 5)
call sky_block (SKY_SKB(par), dosky, dosig, im, bpm, expmap,
skyname, signame, skymap, sigmap, logfd)
default:
call error (1, "Unknown sky type")
}
}
call sfree (sp)
end
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