Collaboration diagram for Get Parameter-SF:

Functions
double	ophSig::sigGetParamSF_CPU (float zMax, float zMin, int sampN, float th)
	Extraction of distance parameter using sharpness functions by using CPU. More...

double	ophSig::sigGetParamSF_GPU (float zMax, float zMin, int sampN, float th)
	Extraction of distance parameter using sharpness functions by using GPU. More...

double	ophSig::sigGetParamSF (float zMax, float zMin, int sampN, float th)
	Extraction of distance parameter using sharpness functions. More...

Detailed Description

This module is related method which extraction of distance parameter using sharpness function maximization method.

Introduction

We use autofocusing to capture in-focus images. It is based on sharpness of images and various of autofocusing algorithms have been proposed. It represents a peak when the image is in-focus and drops when the image goes out-of-focus. It can relate to holography signal process. Hologram has a depth information of object and is reconstructed at that point. The sharpness of the reconstructed hologram image changes with the change of the depth position.
If the depth of focus is not correct, the reconstructed hologram can not have a clear image. It means the same as in-focus image phenomenon. For this reasons, we will discuss the hologram signal processing using the sharpness functions.

Brenner function [1] : A focus function f(Z) is calculated which is a measure of the average change in gray level between pairs of points separated by n pixels. f(Z) is a maximum when the image is in focus. and is given by
\[ f(Z)=\sum_{j}\sum_{i}\left| G_i(Z)-G_{ij}(Z)\right|^2 \]
Where the index (i) ranges over all image points, in order along a scan line (j); n is a small integer; Z is the Z-axis, or focus position; and \(G_i\) is the transmission gray level for point i. A value of n equal to 2 gives a good signal to noise ratio.

Figure 1. Concept of searching distance parameter.
Reconstruct the hologram to sequential depth positions using Fresnel diffraction method. then we can obtain \( f(Z) \) of reconstructed hologram image. if \(f(Z)\) is maximum value, value of \(Z\) is distance parameter of hologram.

[1] J. Brenner et al., "An Automated Microscope for Cytologic Research - A Preliminary Evaluation", Journal of Histochemistry and Cytochemistry, vol. 24, no. 1, pp. 100-111, 1976

double ophSig::sigGetParamSF	(	float	zMax,
		float	zMin,
		int	sampN,
		float	th
	)

Extraction of distance parameter using sharpness functions.

Parameters

zMax	Maximum value of distance on z axis
zMin	Minimum value of distance on z axis
sampN	Count of search step
th	Threshold value

Definition at line 1080 of file ophSig.cpp.

double ophSig::sigGetParamSF_CPU	(	float	zMax,
		float	zMin,
		int	sampN,
		float	th
	)

protected

Extraction of distance parameter using sharpness functions by using CPU.

Parameters

zMax	Maximum value of distance on z axis
zMin	Minimum value of distance on z axis
sampN	Count of search step
th	Threshold value

Definition at line 1507 of file ophSig.cpp.

double ophSig::sigGetParamSF_GPU	(	float	zMax,
		float	zMin,
		int	sampN,
		float	th
	)

protected

Extraction of distance parameter using sharpness functions by using GPU.

Parameters

zMax	Maximum value of distance on z axis
zMin	Minimum value of distance on z axis
sampN	Count of search step
th	Threshold value

Definition at line 393 of file ophSig_GPU.cpp.