Image Management

Working with a directory of images

msumastro.image_collection Module

Classes

ImageFileCollection([location, keywords, ...])

Representation of a collection of image files.

Turning an image collection into a tree

class msumastro.table_tree.TableTree(*args)

Base class for grouping images hierarchically into a tree based on metadata

This class can be used directly, though subclasses for a few common cases are provided in this package.

Parameters:

table : astropy.table.Table instance

Table containing the metadata to be used for grouping images.

tree_keys : list of str

Keys to be used in grouping images. Each key must be the name of a column in table.

index_key : str

Key which is used to indicate which rows of the input table are in each group; it must be the name of one of the columns in table. Values of the index must uniquely identify rows of the table (in database parlance, index must be able to serve as a primary key for the table).

Raises:

TypeError

Raised if the number of initialization arguments is incorrect or the types of any of the arguments is incorrect.

Attributes

table	astropy.table.Table of metadata used to group rows.
tree_keys	list of str, Table columns to be used in grouping the rows.
index_key	str, Name of column whose values uniquely identify each row.

index_key

str, Name of column whose values uniquely identify each row.

table

astropy.table.Table of metadata used to group rows.

tree_keys

list of str, Table columns to be used in grouping the rows.

walk(*args, **kwd)

Walk the grouped tree

The functionality provided is similar to that in os.walk: starting at the top of tree, yield a tuple of return values indicating parents, children and rows at each level of the tree.

Parameters:

None

Returns:

parents, children, index : lists

parents : list

Dictionary keys that led to this return

children : list

Child nodes at this level

index : list

Index values for the items in the table that correspond to the values in parents

Image class that includes WCS information

class msumastro.image.ImageWithWCS(filepath, **kwd)

FITS image with WCS

A FITS images with a few convenience methods defined, including easy access to WCS transforms.

Parameters:

filepath : str

Path to the FITS file.

kwd : dict, optional

All keywords are passed through to astropy.io.fits.open

Attributes

data	Image data; will be scaled by default using BZERO and BSCALE
header	FITS header for this file
wcs	WCS object for this file

close()

Close the file associated with this FITS image.

data

Image data; will be scaled by default using BZERO and BSCALE

header

FITS header for this file

save(fname, clobber=False)

Save FITS file.

Parameters:

fname : str

Name of the file to save to

clobber : bool, optional

Set to True to overwrite an existing file.

shift(int_shift, in_place=False)

Shift image by an integer number of pixels without interpolation.

Parameters:

int_shift : list-like of two integers

Amount by which image should be shifted; floats will be rounded.

in_place : bool, optional

If True the image is shifted in place, and the wcs reference pixel is updated appropriately. Otherwise an array is returned that is shifted with no WCS information.

Raises:

ValueError

If the shift is not by an integer amount.

wcs

WCS object for this file

wcs_pix2world(pix, **kwargs)

Wrapper around astropy.wcs function that handles a single tuple gracefully.

Parameters:

pix : numpy array either of dimension 2 (e.g. [xpix, ypix]) or Nx2

Pixel positions at which sky coordinates should be calculated.

Returns:

numpy.ndarray with same shape as pix.

Sky coordinates for each input pixel.

wcs_world2pix(sky, **kwargs)

Wrapper around astropy.wcs function that handles a single tuple gracefully.

Parameters:

sky : numpy array either of dimension 2 (e.g. [xpix, ypix]) or Nx2

Pixel positions at which sky coordinates should be calculated.

Returns:

numpy.ndarray with same shape as sky.

Pixel positions for each input sky coordinate.