CFwhm:Class Description

CFwhm Class Description

The CFwhm class is used to compute the Full Width at Half Maximum for an image feature. This class provides methods for calculating the FWHM and for working with control parameters. The centroid computation collects points around a central position, then fits a Gaussian + Constant model to the data. The fit parameters lead to the FWHM value, the background value, and the peak value of the point spread function. Both peaks and valleys can be measured. The Calc method usually uses a centroid position as the center point of the FWHM calculation.

Usage

Construction

Object = new_fwhm()

Object = CFwhm:new()

Destruction

Object:delete()

Properties

The properties in the table below may be accessed directly. However, it is better programming style to access them using the provided Get... and Set... methods when available.

radiusX	The pixel radius for computing the centroid position in the x direction.
radiusY	The pixel radius for computing the centroid position in the y direction.
trackX	The pixel radius for tracking the peak or valley in the x direction from the initial position to the centroid position.
trackY	The pixel radius for tracking the peak or valley in the y direction from the initial position to the centroid position.
bPositive	True if centroids are computed for peaks, or false if computed for valleys.
nMinIter	The minimum number of iterations used in fitting the radial intensity profile.
bSnWeighting	True to weight the data by signal to noise ratio when computing the fit.
bAutoCentroid	True computes the centroid before fitting the radial profile data.
nInitialFwhm	The trial value, in pixels, of the FWHM used in the iterative solution.
nMaxRadius	The maximum radius in pixels, of the radial profile sample.

Creation - Non-class Functions

This function is normally used to create a new CFwhm object as an alternative to the class-based new method.

new_fwhm

Creates a new instance of a CFwhm object.

Construction and Destruction - Class Methods

new	Creates a new instance of a CFwhm object.
delete	Deletes the instance of the CFwhm object.

Data Member Access

GetSign	Returns true if the FWHM and centroid are being computed for peaks, rather than for valleys.
GetSample	Returns the centroid sample radius in x and y directions.
GetTracking	Returns the centroid tracking radius in x and y directions.
SetSign	Sets the centroid calculation to use peaks (true) or valleys (false).
SetSample	Sets the centroid sample radius in x and y directions to the specified number of pixels.
SetTracking	Sets the centroid tracking radius in x and y directions to the specified number of pixels.
GetAutoCentroid	Returns true if the auto-centroid flag is set and the FWHM uses a centroid position.
SetAutoCentroid	Sets the auto-centroid flag true or false.
GetMaxRadius	Returns the maximum profile sampling radius, in pixels.
SetMaxRadius	Sets the maximum profile sample radius.

Operations