javax.media.jai
Class WarpQuadratic

java.lang.Object
  javax.media.jai.Warp
      javax.media.jai.WarpPolynomial
          javax.media.jai.WarpQuadratic

All Implemented Interfaces:

Serializable

public final class WarpQuadratic

extends WarpPolynomial

A quadratic-based description of an image warp.

The source position (x', y') of a point (x, y) is given by the quadratic bivariate polynomials:

 x' = p(x, y) = c1 + c2*x + c3*y + c4*x^2 + c5*x*y + c6*y^2
 y' = q(x, y) = c7 + c8*x + c9*y + c10*x^2 + c11*x*y + c12*y^2
 

WarpQuadratic is marked final so that it may be more easily inlined.

See Also:

WarpPolynomial, Serialized Form

Field Summary

Fields inherited from class javax.media.jai.WarpPolynomial

degree, postScaleX, postScaleY, preScaleX, preScaleY, xCoeffs, yCoeffs

Constructor Summary

WarpQuadratic(float[] xCoeffs, float[] yCoeffs)
Constructs a WarpQuadratic with pre- and post-scale factors of 1.

WarpQuadratic(float[] xCoeffs, float[] yCoeffs, float preScaleX, float preScaleY, float postScaleX, float postScaleY)
Constructs a WarpQuadratic with a given transform mapping destination pixels into source space.

Method Summary

Point2D	mapDestPoint(Point2D destPt) Computes the source point corresponding to the supplied point.
float[]	warpSparseRect(int x, int y, int width, int height, int periodX, int periodY, float[] destRect) Computes the source subpixel positions for a given rectangular destination region, subsampled with an integral period.

Methods inherited from class javax.media.jai.WarpPolynomial

createWarp, getCoeffs, getDegree, getPostScaleX, getPostScaleY, getPreScaleX, getPreScaleY, getXCoeffs, getYCoeffs

Methods inherited from class javax.media.jai.Warp

mapDestRect, mapSourcePoint, mapSourceRect, warpPoint, warpPoint, warpRect, warpRect, warpSparseRect

Methods inherited from class java.lang.Object

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

Constructor Detail

WarpQuadratic

public WarpQuadratic(float[] xCoeffs,
                     float[] yCoeffs,
                     float preScaleX,
                     float preScaleY,
                     float postScaleX,
                     float postScaleY)

Constructs a WarpQuadratic with a given transform mapping destination pixels into source space. Note that this is a backward mapping as opposed to the forward mapping used in AffineOpImage. The coeffs arrays must each contain 6 floats corresponding to the coefficients c1, c2, etc. as shown in the class comment.

Parameters:

xCoeffs - The six destination to source transform coefficients for the X coordinate.

yCoeffs - The six destination to source transform coefficients for the Y coordinate.

preScaleX - The scale factor to apply to input (dest) X positions.

preScaleY - The scale factor to apply to input (dest) Y positions.

postScaleX - The scale factor to apply to the result of the X polynomial evaluation

postScaleY - The scale factor to apply to the result of the Y polynomial evaluation

Throws:

IllegalArgumentException - if the xCoeff and yCoeff arrays do not each have size entries.

WarpQuadratic

public WarpQuadratic(float[] xCoeffs,
                     float[] yCoeffs)

Constructs a WarpQuadratic with pre- and post-scale factors of 1.

Parameters:

xCoeffs - The 6 destination to source transform coefficients for the X coordinate.

yCoeffs - The 6 destination to source transform coefficients for the Y coordinate.

Throws:

IllegalArgumentException - if the xCoeff and yCoeff arrays do not each have size entries.

Method Detail

warpSparseRect

public float[] warpSparseRect(int x,
                              int y,
                              int width,
                              int height,
                              int periodX,
                              int periodY,
                              float[] destRect)

Computes the source subpixel positions for a given rectangular destination region, subsampled with an integral period. The destination region is specified using normal integral (full pixel) coordinates. The source positions returned by the method are specified in floating point.

Specified by:

warpSparseRect in class Warp

Parameters:

x - The minimum X coordinate of the destination region.

y - The minimum Y coordinate of the destination region.

width - The width of the destination region.

height - The height of the destination region.

periodX - The horizontal sampling period.

periodY - The vertical sampling period.

destRect - A float array containing at least 2*((width+periodX-1)/periodX)* ((height+periodY-1)/periodY) elements, or null. If null, a new array will be constructed.

Returns:

A reference to the destRect parameter if it is non-null, or a new float array otherwise.

Throws:

ArrayBoundsException - if destRect is too small

mapDestPoint

public Point2D mapDestPoint(Point2D destPt)

Computes the source point corresponding to the supplied point.

This method returns the value of pt in the following code snippet:

 double x1 = (destPt.getX() + 0.5F)*preScaleX;
 double x2 = x1*x1;

 double y1 = (destPt.getY() + 0.5F)*preScaleY;
 double y2 = y1*y1;

 double x = c1 + c2*x1 + c3*y1 + c4*x2 + c5*x1*y1 + c6*y2;
 double y = c7 + c8*x1 + c9*y1 + c10*x2 + c11*x1*y1 + c12*y2;

 Point2D pt = (Point2D)destPt.clone();
 pt.setLocation(x*postScaleX - 0.5, y*postScaleY - 0.5);
 

Overrides:

mapDestPoint in class WarpPolynomial

Parameters:

destPt - the position in destination image coordinates to map to source image coordinates.

Returns:

a Point2D of the same class as destPt.

Throws:

IllegalArgumentException - if destPt is null.

Since:

JAI 1.1.2