NAME

dqenormx -- Normalize a relative detective efficiency (DE) image to unity.

USAGE

dqenormx input output

DESCRIPTION

A relative DE file is a normalized image which gives the variations in instrument sensitivity at a certain wavelength over the entire image. The dqenormx task will normalize the image, generating the relative DE file.

The parameters x1, x2, y1, and y2 may be used to specify a subsection of the input image that will be used to compute an average. These parameters are pixel numbers relative to an image section that may have been specified in the input image name.

This task computes the average pixel value, ignoring values outside a specified range; the input image is then divided by this average to generate the output image.

The input image is expected to have been corrected for any non-uniformity in the illumination. The corrected file should have the keyword CALTYPE set to "SOURCE_NORMALISED". The dqenormx task checks CALTYPE to verify that the file has indeed been corrected, and issues a warning if the illumination has not been corrected. The output image has keyword FILETYPE set to "UNI", as required by the Routine Science Data Processing (RSDP) system.

PARAMETERS

input [file name template]

The input image from which the relative DE file will be generated.

output [file name template]

File name for the output image created by dqenormx.

(x= INDEF) [integer]

The parameters x1, x2, y1, and y2 specify the section of infile that is to be used when calculating the normalizing factor. This parameter represents the lower end of the section's X axis. The default is to use all of infile.

(x= INDEF) [integer]

This parameter delineates the image section to be used by specifying the upper range of the X axis. The default is to use all of infile.

(y= INDEF) [integer]

This parameter delineates the image section to be used by specifying the lower range of the Y axis. The default is to use all of infile.

(y= INDEF) [integer]

This parameter delineates the image section to be used by specifying the upper range of the Y axis. The default is to use all of infile.

(upper = INDEF) [real]

Upper threshold of valid pixel values used in calculating the normalizing value. Pixels having values greater than or equal to upper will be ignored. The default (INDEF) is to process all pixels.

(lower = INDEF) [real]

Lower threshold of valid pixel values used in calculating the normalizing value. Pixels having values less than or equal to lower will be ignored. The default (INDEF) is to process all pixels.

EXAMPLES

1. Normalize the input image "in" averaging only the area between 20,30 and 500,500.

  fo> dqenormx in out x1=20 x2=500 y1=30 y2=500

BUGS

REFERENCES

This task was written by David Giaretta.

SEE ALSO

ratiox

Type "help focphot opt=sys" for a higher-level description of the focphot package.