LSQ Equation Construction and Solving

JWST pipeline step for image intensity matching for MIRI images.


Mihai Cara

class jwst.mrs_imatch.mrs_imatch_step.MRSIMatchStep(name=None, parent=None, config_file=None, _validate_kwds=True, **kws)[source]

MRSIMatchStep: Subtraction or equalization of sky background in MIRI MRS science images.

Create a Step instance.

  • name (str, optional) – The name of the Step instance. Used in logging messages and in cache filenames. If not provided, one will be generated based on the class name.

  • parent (Step instance, optional) – The parent step of this step. Used to determine a fully-qualified name for this step, and to determine the mode in which to run this step.

  • config_file (str path, optional) – The path to the config file that this step was initialized with. Use to determine relative path names of other config files.

  • **kws (dict) – Additional parameters to set. These will be set as member variables on the new Step instance.

class_alias = 'mrs_imatch'

This is where real work happens. Every Step subclass has to override this method. The default behaviour is to raise a NotImplementedError exception.

reference_file_types = []
spec = "\n        # General sky matching parameters:\n        bkg_degree = integer(min=0, default=1) # Degree of the polynomial for background fitting\n        subtract = boolean(default=False) # subtract computed sky from 'images' cube data?\n\n    "
jwst.mrs_imatch.mrs_imatch_step.apply_background_2d(model2d, channel=None, subtract=True)[source]

Apply (subtract or add back) background values computed from meta.background polynomials to 2D image data.

This function modifies the input model2d’s data.


This function does not check whether background was previously applied to image data (through meta.background.subtracted).


This function does not modify input model’s meta.background.subtracted attribute to indicate that background has been applied to model’s data. User is responsible for setting meta.background.subtracted after background was applied to all channels. Partial application of background (i.e., to only some channels as opposite to all channels) is not recommended.

  • model2d (jwst.datamodels.image.ImageModel) – A jwst.datamodels.image.ImageModel from whose data background needs to be subtracted (or added back).

  • channel (str, int, list, None, optional) – This parameter indicates for which channel background values should be applied. An integer value is automatically converted to a string type. A string type input value indicates a single channel to which background should be applied. channel can also be a list of several string or integer single channel values. The default value of None indicates that background should be applied to all channels.

  • subtract (bool, optional) – Indicates whether to subtract or add back background values to input model data. By default background is subtracted from data.