2.1.2.1.5. sf_tools.image.stamp module

IMAGE STAMP SELECTION ROUTINES

This module contains methods for selecting stamps or patches from images.

Author:Samuel Farrens <samuel.farrens@gmail.com>
Version:1.0
Date:20/10/2017
sf_tools.image.stamp.patch_centres(data_shape, layout)[source]

Image centres

This method inds the centres of the patches in a 2D map.

Parameters:
  • data_shape (tuple) – Shape of the 2D map
  • layout (tuple) – Layout of the patches
Returns:
Return type:

np.ndarray array of patch centres
sf_tools.image.stamp.postage_stamp(data, pos, pixel_rad)[source]

Postage stamp

This metho selects a postage stamp of a given size from a 2D-array.

Parameters:
  • data (np.ndarray) – Input data array
  • pos (tuple) – Position of postage stamp centre
  • pixel_rad (tuple) – Pixel radius in each dimension (i.e. size of the stamp from centre)
Returns:
Return type:

np.ndarray rearanged matrix of kernel elements

Notes

The image edges are padded with zeros.

sf_tools.image.stamp.pixel_pos(array_shape)[source]

Pixel positions

This method returns all of the pixel positions from a 2D-array.

Parameters:array_shape (tuple) – Shape of array
Returns:
Return type:list of pixel positions
class sf_tools.image.stamp.FetchStamps(data, pixel_rad, all=False)[source]

Bases: object

Fetch postage stamps

This class returns a stack of postage stamps from a given 2D image array.

Parameters:
  • data (np.ndarray) – Input 2D data array
  • pixel_rad (tuple) – Pixel radius in each dimension
  • all (boolean, optional) – Option to select all pixels. Default (all=False)
_check_inputs()[source]

Check inputs

This method checks the class variable values.

Raises:ValueError – For invalid array dimensions or pixel radius values
_pad_data()[source]

Pad data

This method pads the input array with zeros.

_adjust_pixels()[source]

Adjust pixels

This method adjusts the pixel positions according to the pixel radius.

get_pixels(pixels)[source]

Get pixels

This method gets the desired pixel positions.

Parameters:pixels (list or np.ndarray) – List of pixel positions
Raises:ValueError – For invalid number of dimensions for pixel position array
n_pixels(n_pixels=None, random=False)[source]

Number of pixels

This method selects a specified number of pixel positions.

Parameters:
  • n_pixels (int, optional) – Number of pixels to keep. Default (n_pixels=None)
  • random (bool, optional) – Option to select random pixel position
_stamp(pos, func=None, *args)[source]

Stamp

This method retrieves a postage stamp from the padded input data at a given position.

Parameters:
  • pos (tuple) – Pixel position in 2D padded array.
  • func (function, optional) – Optional function to be applied to postage stamp.
Returns:
Return type:

np.ndarray postage stamp array or result of func
Raises:

ValueError – For for invalid size of pixel position.
scan(func=None, *args, **kwargs)[source]

Scan stamps

This method scans the 2D padded input array and retrieves the postage stamps at all the desired pixel positions.

Parameters:func (function, optional) – Optional function to be applied to postage stamps.
Returns:
Return type:np.ndarray postage stamp arrays or results of func