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GIRAFFE Pipeline Reference Manual |
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Bias Handling
Detailed DescriptionTBD Function Documentation
Removes the bias from an image.
This is the first processing of any Giraffe raw image. It is the only function operating on images larger than the CCD active area (pre/overscans present) and using ADU units. The bias areas in the prescan and overscan lanes in both, x and y, directions are defined through the matrix_biaslimits argument. A 2D plane or curve is fitted on the data, or the mean value is calculated, in these bias areas and the linear coefficients describing the plane or mean value are saved as quality indicators. The control parameter config->method is used to differentiate various level of the processing: the single valued average subtraction, the plane subtraction and the master_bias subtraction without or with zero adjustment. In any case the pre/overscans are removed prior the bias subtraction (the master_bias not having necessarily the same size of pre/overscans as rawFrame) and raw_frame is converted from ADU to e-. Routine has 4 optional parameters which have a default value when not specified: config->method - Bias subtraction method: 'UNIFORM','PLANE','MASTER','ZMASTER','MASTER+PLANE', 'ZMASTER+PLANE','CURVE','MASTER+CURVE','ZMASTER+CURVE' default: 'UNIFORM' config->remove - Remove Bias? Default TRUE 3 bias sigma clipping parameters:
4 Chebyshev interpolation parameters in bias areas
Definition at line 3114 of file gibias.c. References giraffe_get_raw_areas(), giraffe_image_get(), giraffe_image_get_properties(), giraffe_image_set(), giraffe_image_set_properties(), and giraffe_trim_raw_areas().
Create bias areas from an image.
The function creates bias areas specification matrix based upon the NAXIS1, NAXIS2, PRSCX, PRSCY, OVSCX and OVSCY properties of the image. Definition at line 2720 of file gibias.c. References giraffe_image_get_properties(). Referenced by giraffe_bias_remove().
Remove pre- and overscan ares from an image.
The function removes the pre- and overscan areas from image. The regions to crop are determined from the pre- and overscan image properties (FITS keywords PRSCX, PRSCY, OVSCX and OVSCY). After the removal the affected image properties are updated, including the image world coordinate system if it is present. The function expects that the image has properties associated and returns an error if image does not contain any properties. Definition at line 2922 of file gibias.c. References giraffe_image_get(), giraffe_image_get_properties(), and giraffe_image_set(). Referenced by giraffe_bias_remove(). |