hologradpy.fitting

This module contains functions for curve fitting.

Classes

FitSine

This class is used in the wavefront measurement to fit a 2D sine to the interference pattern on the camera. The

Functions

tilt(xy, *args[, mask])

Fit function containing the first three Zernike polynomials of the form z = c0 + c1 * x + c2 * y + c3 * 2xy.

remove_tilt(img[, mask])

This function removes fits the first three Zernike polynomials (Piston and tilt) to an image and subtracts the

gaussian(xy, *args)

Gaussian fit function.

fit_gaussian(img[, dx, dy, sig_x, sig_y, a, c, ...])

Fits a 2D Gaussian to an image. The image s blurred using a Gaussian filer before fitting.

Module Contents

hologradpy.fitting.tilt(xy, *args, mask=None)

Fit function containing the first three Zernike polynomials of the form z = c0 + c1 * x + c2 * y + c3 * 2xy.

Parameters:

  • xy – x, y coordinate vectors.

  • args – Vector of length 4, containing Zernike coefficients.

Returns:

First 3 Zernike polynomials.

hologradpy.fitting.remove_tilt(img, mask=None)

This function removes fits the first three Zernike polynomials (Piston and tilt) to an image and subtracts the fitted function from the original image. :param ndarray img: Input image. :param ndarray mask: Binary mask in which to remove tilt. :return: Image without tilt.

hologradpy.fitting.gaussian(xy, *args)

Gaussian fit function.

Parameters:

  • xy – x, y coordinate vectors.

  • args – Fitting parameters passed to patterns.gaussian.

Returns:

Gaussian.

hologradpy.fitting.fit_gaussian(img, dx=None, dy=None, sig_x=15, sig_y=15, a=None, c=0, blur_width=10, xy=None)

Fits a 2D Gaussian to an image. The image s blurred using a Gaussian filer before fitting.

Parameters:

  • img – Input image.

  • dx – X-offset of Gaussian [px].

  • dy – Y-offset of Gaussian [px].

  • sig_x – X-width of Gaussian [px].

  • sig_y – -width of Gaussian [px].

  • a – Amplitude.

  • c – Offset.

  • blur_width – Width of Gaussian blurring kernel [px].

  • xy – X, Y meshgrid. If not specified, pixel coordinates are used.

Returns:

Fitting parameters, parameter errors.

class hologradpy.fitting.FitSine(fl, k, dx=None, dy=None)

This class is used in the wavefront measurement to fit a 2D sine to the interference pattern on the camera. The distance between the sample and reference patch can be set by calling the method set_dx_dy.

fl
dx = None
dy = None
k
set_dx_dy(dx, dy)

Method to set parameters dx and dy. :param dx: New dx. :param dy: New dy.

fit_sine(xy, *args)

Method to perform 2D sine fit. :param xy: x, y coordinate vectors. :param args: Args passed to patterns.fringes_wavefront :return: 2D sine.