ResampleStep

class jwst.resample.resample_step.ResampleStep(name=None, parent=None, config_file=None, _validate_kwds=True, **kws)[source]

Bases: JwstStep

Resample input data onto a regular grid using the drizzle algorithm.

Note

When supplied via output_wcs, a custom WCS overrides other custom WCS parameters such as output_shape (now computed from by output_wcs.bounding_box), crpix

Parameters:

input (JwstDataModel or Association) – Single filename for either a single image or an association table.

Create a Step instance.

Parameters:
  • 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 or pathlib.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.

Attributes Summary

class_alias

reference_file_types

spec

Methods Summary

get_drizpars(ref_filename, input_models)

Extract drizzle parameters from reference file.

process(input)

This is where real work happens.

update_fits_wcs(model)

Update FITS WCS keywords of the resampled image.

Attributes Documentation

class_alias = 'resample'
reference_file_types: ClassVar = ['drizpars']
spec
pixfrac = float(default=1.0) # change back to None when drizpar reference files are updated
kernel = string(default='square') # change back to None when drizpar reference files are updated
fillval = string(default='INDEF' ) # change back to None when drizpar reference files are updated
weight_type = option('ivm', 'exptime', None, default='ivm')  # change back to None when drizpar ref update
output_shape = int_list(min=2, max=2, default=None)  # [x, y] order
crpix = float_list(min=2, max=2, default=None)
crval = float_list(min=2, max=2, default=None)
rotation = float(default=None)
pixel_scale_ratio = float(default=1.0) # Ratio of input to output pixel scale
pixel_scale = float(default=None) # Absolute pixel scale in arcsec
output_wcs = string(default='')  # Custom output WCS.
single = boolean(default=False)
blendheaders = boolean(default=True)
allowed_memory = float(default=None)  # Fraction of memory to use for the combined image.
in_memory = boolean(default=True)

Methods Documentation

get_drizpars(ref_filename, input_models)[source]

Extract drizzle parameters from reference file.

This method extracts parameters from the drizpars reference file and uses those to set defaults on the following ResampleStep configuration parameters:

pixfrac = float(default=None) kernel = string(default=None) fillval = string(default=None) wht_type = option(‘ivm’, ‘exptime’, None, default=None)

Once the defaults are set from the reference file, if the user has used a resample.cfg file or run ResampleStep using command line args, then these will overwrite the defaults pulled from the reference file.

process(input)[source]

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

update_fits_wcs(model)[source]

Update FITS WCS keywords of the resampled image.