Module imagingbook.common

Package imagingbook.common.corners

Class SubpixelMaxInterpolator

java.lang.Object

imagingbook.common.corners.SubpixelMaxInterpolator

Direct Known Subclasses:

SubpixelMaxInterpolator.QuadraticLeastSquares, SubpixelMaxInterpolator.QuadraticTaylor, SubpixelMaxInterpolator.Quartic

public abstract class SubpixelMaxInterpolator
extends Object

Common interface for all sub-pixel maximum locator implementations. A sub-pixel maximum locator tries to interpolate the continuous position and value of a local maximum for a discrete 3x3 neighborhood. The center value in the discrete neighborhood is assumed to be a local maximum. See Sec. 6.5 and Appendix E of [1] for additional details.

[1] W. Burger, M.J. Burge, Digital Image Processing – An Algorithmic Introduction, 3rd ed, Springer (2022).

Version:

2022/09/11 revised instance creation

See Also:

• SubpixelMaxInterpolator.QuadraticTaylor
• SubpixelMaxInterpolator.QuadraticLeastSquares
• SubpixelMaxInterpolator.Quartic

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	SubpixelMaxInterpolator.Method	Enumeration of different SubpixelMaxInterpolator methods.
static class	SubpixelMaxInterpolator.QuadraticLeastSquares	2D interpolator based on least-squares fitting a quadratic polynomial
static class	SubpixelMaxInterpolator.QuadraticTaylor	2D interpolator using second-order Taylor expansion to find the coefficients of the quadratic interpolating polynomial
static class	SubpixelMaxInterpolator.Quartic	2D interpolator based on fitting a 'quartic' (i.e., 4th-order) polynomial

Method Summary

Modifier and Type	Method	Description
abstract float[]	getMax(float[] s)	Tries to locate the sub-pixel maximum from the 9 discrete sample values (s0,...,s8) taken from a 3x3 neighborhood, arranged in the following order:

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

getMax

public abstract float[] getMax(float[] s)

Tries to locate the sub-pixel maximum from the 9 discrete sample values (s0,...,s8) taken from a 3x3 neighborhood, arranged in the following order:

 s4 s3 s2
 s5 s0 s1
 s6 s7 s8
 

The center value (s0) is associated with position (0,0).

Parameters:

s - a vector containing 9 sample values in the order described above

Returns:

a 3-element array [x,y,z], with the estimated maximum position (x,y) and the associated max. value (z). This position is relative to the center coordinate (0,0). null is returned if the maximum position could not be located.