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errcreate xray.xspatial



errcreate -- generate a PROS error image (sq of errors) from data image


errcreate input_image output_errimage


Errcreate generates a PROS-style error image from an input data image. A PROS-style error image actually contains the SQUARE of the error values. Two algorithms are implemented: a Poisson error approximation and a pure Gaussian calculation. The algorithm activated is determined by the value of the header keyword, POISSERR. If absent, or set to T the Poisson approximation will be used, if set to F a pure Gaussian calculation will be performed. This parameter value can be set by using either qphedit or hedit for the cases of input QPOE and IMAGE input files, respectively.


input_image = "xdata$snr.qp[bl=2]" prompt = name of input image

The image file for which errors are to be calculated. (This can include an image section or be a QPOE data file name)

output_errimage = "." prompt = root name for output file [root_err.imh]

The name of the output file. The output file is a standard IRAF image file with real*4 data. Its dimensions will be that of the input (after any section and/or blocking reductions).

(clobber = no) [boolean]

Overwrite the existing image file if one exists with the same name as that given by output_image.

(display = 1) [int]

Level of feedback and debug option. If 0, errcreate prints no messages as it processes the image errors. A level of 1, prints the history message and the output filename.


sp> errcreate xdata$snr.qp[bl=2] .
        writing error array to: smi296_err



Documentation on the error algorithms is available in help explain_errors

help qphedit for information on changing the POISSERR keyword in QPOE files

help hedit for information on changing the POISSERR keyword in IMAGE files

Documentition on Documentation on imsmooth(which allows an input error image).

Documentation on imcontoour(which allows an input error image).

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