hermes.pipeline.components.subtractbackground.subtractBackground Class Reference

Subtract the background from an image. More...

Inheritance diagram for hermes.pipeline.components.subtractbackground.subtractBackground:

Public Member Functions
def	__init__
	Make a Hermes component and initialize variables.
def	validateOptions
	Read the options given or adopt default values.
def	__call__
	the run begins here
Public Member Functions inherited from hermes.pipeline.core.pipelinecomponent.PipelineComponent
def	__init__
def	__call__
def	optionsAreValid
def	getOptions
def	setOptions
def	checkExistShapeUnits
def	isOption

Public Attributes
	includeBackgroundVarianceEstimate
	default values for options More...
	isDebug
	use this to True to get intermediary debug results in the debug folder
	results
Public Attributes inherited from hermes.pipeline.core.pipelinecomponent.PipelineComponent
	options
	logger
	ConsoleLogSeverity
	default value
	canShowGraphics
	when machine does not run matplotlib. More...

Detailed Description

Subtract the background from an image.

PURPOSE :

This module subtract the background modelled in modelBackground from the
input frame and performs the associated error progression. Error estimates
do not take into account deviations due to the fact that the background
model can be unrealistic.



COMMENTS :

In general, background subtraction based on an interpolation of mid-order
observed counts will overestimate the background in case that the wings of
the spectral orders overlap in cross-order direction. This leads to negative
fluxes in the core of completely black lines. The strongest telluric lines in
the extracted spectral orders are a good test-case to identify this type of
error in the background estimation.




INPUT CONSTANTS FROM INSTRUMENT MODEL :





INPUT DATA FROM RESULTDICT :

MANDATORY :

    from remove2dFlatField, a 2d flat-fielded image:
        image
        variance over that image (error image)

    from modelBackground:
        model image
        variance over that model image (error image)

    if "subtractBackground" already in the header, exit.





OPTIONS READ FROM OPTIONDICT :

includeBackgroundVarianceEstimate = True / False
    default value = False

isDebug = False             # default value
    writes fits files with background subtracted to "t30subtractedbackground.fits"
    and "t30subtractedbackgroundvariance.fits"



OUTPUT :

output
varOutput   :   image and error image

write in header : 'subtractBackground = "yes"'

##  QUESTION : shouldn't it be better to write
    'subtractBackground done by USER at DATETIME' ?
    It would provide useful information.
    IF we change the name of the input image, is there really a need to
    record a 'subtractBackground = "yes"' in the header ?
    Should we update the fits file with this ?

Member Data Documentation

hermes.pipeline.components.subtractbackground.subtractBackground.includeBackgroundVarianceEstimate

default values for options

use includeBackgroundVarianceEstimate to get the value

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The documentation for this class was generated from the following file:

• pipeline/components/subtractbackground.py