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diff --git a/noao/twodspec/multispec/doc/newimage.hlp b/noao/twodspec/multispec/doc/newimage.hlp new file mode 100644 index 00000000..1ef7fbe0 --- /dev/null +++ b/noao/twodspec/multispec/doc/newimage.hlp @@ -0,0 +1,130 @@ +.help newimage Jul84 noao.twodspec.multispec +.ih +NAME +newimage -- Create a new multi-spectra image +.ih +USAGE +newimage image output +.ih +PARAMETERS +.ls image +Image to be used to create the new image. +.le +.ls output +Filename for the new multi-spectra image. +.le +.ls lower = -10 +Lower limit for model profiles. It is measured in pixels from the +spectra centers defined by the position functions in the database. +.le +.ls upper = -10 +Upper limit for model profiles. It is measured in pixels from the +spectra centers defined by the position functions in the database. +.le +.ls lines = "*" +Image lines of the multi-spectra image to be in the new multi-spectra image. +.le +.ls ex_model = no +Create a model image? +.le +.ls clean = yes +Replace bad pixels with model values? The following parameters are used: +.ls nreplace = 1000. +Maximum number of pixels to be replaced per image line when cleaning with +model \fIgauss5\fR or maximum number of pixels to be replaced per spectrum when +cleaning with model \fIsmooth\fR. +.le +.ls sigma_cut = 4. +The cleaning threshold in terms of the predicted pixel sigma. +.le +.ls niterate = 1 +Maximum number of cleaning iterations per line when cleaning with model +\fIgauss5\fR. +.le +.le +.ls model = "smooth" +Choice of \fIgauss5\fR or \fIsmooth\fR. Minimum match abbreviation is +allowed. This parameter is required only if \fIex_model\fR = yes +or \fIclean\fR = yes. +.le +.ls fit_type = 2 +Model fitting algorithm for model \fIgauss5\fR. +.le +.ls naverage = 20 +Number of lines to be averaged in model \fIsmooth\fR. +.le +.ls interpolator = "spline3" +Type of image interpolation function to be used. +The choices are "nearest", "linear", "poly3", "poly5", and "spline3". +Minimum match abbreviation is allowed. +.le +.ls verbose = no +Print verbose output? +.le +.ih +DESCRIPTION +A new multi-spectra image is created using the description of the +multi-spectra image in the MULTISPEC database associated with \fIimage\fR. +The user selects the image \fIlines\fR from the original image to be in +the new image. The options allow the creation of model images or images in +which the bad or deviant pixels are replaced by model profile values. + +If \fIex_model\fR = yes or \fIclean\fR = yes model +spectra are fit to the spectra in the image. There are two models: +a five parameter Gaussian profile called \fIgauss5\fR and profiles obtained +by averaging \fInaverage\fR image lines surrounding the image line being +modeled called \fIsmooth\fR. The model is selected with the parameter +\fImodel\fR. + +When \fIex_model\fR = yes an image containing model spectra is produced. + +When \fIclean\fR = yes pixels with large residuals from the model are +detected and removed from the model fit. The selected model is +fit to the pixels which are not in the bad pixel list (not yet implemented) +and which have not been removed from the model fit. The sigma of the fit +is computed. Deviant pixels are detected by comparing them to the model +to determine if they differ by more than \fIsigma_cut\fR times the sigma. +The model fit is iterated, removing deviant pixels at each iteration, until +no more pixels are found deviant or \fInreplace\fR pixels have been found. +The pixels removed or in the bad pixel list are then replaced with +model values. (To clean and extract the spectra with this algorithm see +\fBmsextract\fR.) + +There are some technical differences in the model fitting and cleaning +algorithms for the two models. In model \fIsmooth\fR +the fit for the profile scale factors is done independently for each spectrum +and automatically corrected when a bad pixel is detected. This fitting process +is fast and rigorous. The parameter \fInreplace\fR in this model refers to +the maximum number of pixels replaced \fIper spectrum\fR. + +In model \fIgauss5\fR, however, the profile scale factors are fit +to the entire image line (hence its ability to fit blended spectra). +There are two fitting algorithms; a rigorous simultaneous fit +and an approximate method. The simultaneous fit is selected when +\fIfit_type\fR = 1. This step is relatively slow. The +alternative method of \fIfit_type\fR = 2 sets the scale factor for each +spectrum by taking the median scale, where scale = data / model profile, +for the three pixels nearest the center of the profile. The median +minimizes the chance of a large error due to a single bad pixel. This +scale may be greatly in error in the case of extreme blending but is also +quite fast; the extraction time is reduced by at least 40%. +The steps of profile fitting and deviant pixel detection are alternated +and the maximum number of iterations through these two steps is +set by \fIniterate\fR. The default of 1 means that the model fitting is not +repeated after detecting deviant pixels. + +The option \fIverbose\fR can be used to print the image lines being extracted +and any pixels replaced by the cleaning process. +.ih +EXAMPLES +To create a cleaned version of the image using model \fIsmooth\fR for cleaning: + + cl> newimage image newimage + +To create an model image using model \fIgauss5\fR: + + cl> newimage image newimage ex_model=yes model="gauss5" +.ih +SEE ALSO +msextract +.endhelp |