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diff --git a/noao/imred/dtoi/doc/hdtoi.hlp b/noao/imred/dtoi/doc/hdtoi.hlp new file mode 100644 index 00000000..bf4355f0 --- /dev/null +++ b/noao/imred/dtoi/doc/hdtoi.hlp @@ -0,0 +1,88 @@ +.help hdtoi May88 imred.dtoi +.ih +NAME +hdtoi -- transform images according to hd curve +.ih +USAGE +hdtoi input output database +.ih +PARAMETERS +.ls input +List of images to be transformed. +.le +.ls output +List of output image names. +.le +.ls database +Name of text database describing HD curve. +.le +.ls fog = "" +Value of fog level, read from database if unspecified. +.le +.ls option = "mean" +Option for calculating fog density when \fBfog\fR is a file list, can be +either "mean" or "median". +.le +.ls sigma = 3.0 +If \fBfog\fR is a file name, and \fBoption\fR = "mean", the mean fog density +is iteratively calculated using this rejection criteria. +.le +.ls floor = 0.0 +Value assigned to levels below fog, can be either 0.0 or -1.0. +.le +.ls ceiling = 30000. +The final intensities are scaled to this value, such that a saturated +input density equals \fBceiling\fR on output. +.le +.ls datatype = "r" +Datatype of output image pixels. +.le +.ls verbose = yes +Print log of processing to STDOUT. +.le +.ih +DESCRIPTION +Task \fIhdtoi\fR transforms one image to another as described by the +\fBdatabase\fR. There is only one HD curve per run; the same +transformation is applied to all input images. + +The fog value can be obtained in three ways: read from the database, read +as a floating point number, or calculated from a list of fog images. If +parameter \fBfog\fR is not specified, the fog value is read from +\fBdatabase\fR. If \fBfog\fR is specified, it can be entered +as either a floating point number or as a list of file names. If the +value cannot be read as a number, it is assumed to be a file name. In that +case, the density of each file in the fog list is calculated and the +average of these values is subtracted from \fBinput\fR before processing. +The algorithm used to calculate the fog density is selected by the +\fBoption\fR parameter, and is either a "mean" or "median" calculation. +The fog density can be the mean value after pixels more than the specified +number of sigma have been rejected, or the median value of all the fog spot +pixels. + +The fog value is subtracted from the input image before the transformation +takes place. It is possible that some density values will fall below +the fog level; these values are handled in one of two ways. Values +below the fog value are set equal to 0.0 when \fBfloor\fR = 0.0. If +\fBfloor\fR = -1.0, the resulting intensity = -1 * intensity (abs (value)). + +A scaling factor is applied to the final intensities, as typically +they will be < 1.0. The \fBceiling\fR parameter is used to specify what +value a saturated density is transformed to; all intensities are scaled +to this upper limit. The precision of the transformation is unaffected by +this parameter, although caution must be used if the output image pixel +type is an integer. The user is responsible for choosing +a \fBceiling\fR that avoids the truncation of significant digits. +.ih +EXAMPLES +Convert three density images to intensity images as described in database db1. + + cl> hdtoi denin* intim1,intim2,intim3 db1 +.ih +TIME REQUIREMENTS +Task \fBhdtoi\fR requires 20 cpu seconds to transform a 512 square image, with +a 12 bit data range, on a VAX 750 +.ih +SEE ALSO +spotlist, dematch, hdfit +.endhelp |