statistics_plot

pyspeckle.pyspeckle.statistics_plot(x, initialize=True)

Plot the first and second-order statistics of a speckle pattern.

This routine calculates and plots the probability density function, PDF and the power spectral density, PSD.

The PDF conforms to the formal definition that it integrate to unity. Also displayed is the contrast defined as the quotient of the standard deviation and the mean.

Note that the PSD can be used to establish the dimensions of the minimum speckle size. When the display reaches the edge of the image, the speckle pattern (in that dimension) is at Nyquist, i.e., two pixels per (minimum) speckle. When the display occupies half of the image, the minimum speckle size is four pixels, etc. Of course this criterion applies separately in each dimension (horizontal and vertical); the speckle pattern need not be isotropic.

Finally note that the display of the speckle pattern is the square root of its intensity. The square root operation has the effect of compressing the dynamic range of the pattern. A fully developed speckle pattern is of such high contrast (theoretically unity) that a display of the intensity itself does not reveal the nuance of the pattern.

Parameters

x – speckle pattern to be analyzed

Returns

nothing