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java.awt.image
public class: BandCombineOp [javadoc | source]

java.lang.Object
   java.awt.image.BandCombineOp

All Implemented Interfaces:
    RasterOp

This class performs an arbitrary linear combination of the bands in a Raster, using a specified matrix.

The width of the matrix must be equal to the number of bands in the source Raster, optionally plus one. If there is one more column in the matrix than the number of bands, there is an implied 1 at the end of the vector of band samples representing a pixel. The height of the matrix must be equal to the number of bands in the destination.

For example, a 3-banded Raster might have the following transformation applied to each pixel in order to invert the second band of the Raster.

[ 1.0 0.0 0.0 0.0 ] [ b1 ]
[ 0.0 -1.0 0.0 255.0 ] x [ b2 ]
[ 0.0 0.0 1.0 0.0 ] [ b3 ]
[ 1 ]

Note that the source and destination can be the same object.

Field Summary
float[][]	matrix
int	nrows
int	ncols
RenderingHints	hints

Constructor:

public BandCombineOp(float[][] matrix, RenderingHints hints) { nrows = matrix.length; ncols = matrix[0].length; this.matrix = new float[nrows][]; for (int i=0; i < nrows; i++) { /* Arrays.copyOf is forgiving of the source array being * too short, but it is also faster than other cloning * methods, so we provide our own protection for short * matrix rows. */ if (ncols > matrix[i].length) { throw new IndexOutOfBoundsException("row "+i+" too short"); } this.matrix[i] = Arrays.copyOf(matrix[i], ncols); } this.hints = hints; } Constructs a BandCombineOp with the specified matrix. The width of the matrix must be equal to the number of bands in the source Raster, optionally plus one. If there is one more column in the matrix than the number of bands, there is an implied 1 at the end of the vector of band samples representing a pixel. The height of the matrix must be equal to the number of bands in the destination. The first subscript is the row index and the second is the column index. This operation uses none of the currently defined rendering hints; the RenderingHints argument can be null. Parameters: matrix - The matrix to use for the band combine operation. hints - The RenderingHints object for this operation. Not currently used so it can be null.

Method from java.awt.image.BandCombineOp Summary:
createCompatibleDestRaster,   filter,   getBounds2D,   getMatrix,   getPoint2D,   getRenderingHints

Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait

Method from java.awt.image.BandCombineOp Detail:
public WritableRaster createCompatibleDestRaster(Raster src) { int nBands = src.getNumBands(); if ((ncols != nBands) && (ncols != (nBands+1))) { throw new IllegalArgumentException("Number of columns in the "+ "matrix ("+ncols+ ") must be equal to the number"+ " of bands ([+1]) in src ("+ nBands+")."); } if (src.getNumBands() == nrows) { return src.createCompatibleWritableRaster(); } else { throw new IllegalArgumentException("Don't know how to create a "+ " compatible Raster with "+ nrows+" bands."); } } Creates a zeroed destination Raster with the correct size and number of bands. An IllegalArgumentException may be thrown if the number of bands in the source is incompatible with the matrix. See the class comments for more details.
public WritableRaster filter(Raster src, WritableRaster dst) { int nBands = src.getNumBands(); if (ncols != nBands && ncols != (nBands+1)) { throw new IllegalArgumentException("Number of columns in the "+ "matrix ("+ncols+ ") must be equal to the number"+ " of bands ([+1]) in src ("+ nBands+")."); } if (dst == null) { dst = createCompatibleDestRaster(src); } else if (nrows != dst.getNumBands()) { throw new IllegalArgumentException("Number of rows in the "+ "matrix ("+nrows+ ") must be equal to the number"+ " of bands ([+1]) in dst ("+ nBands+")."); } if (ImagingLib.filter(this, src, dst) != null) { return dst; } int[] pixel = null; int[] dstPixel = new int[dst.getNumBands()]; float accum; int sminX = src.getMinX(); int sY = src.getMinY(); int dminX = dst.getMinX(); int dY = dst.getMinY(); int sX; int dX; if (ncols == nBands) { for (int y=0; y < src.getHeight(); y++, sY++, dY++) { dX = dminX; sX = sminX; for (int x=0; x < src.getWidth(); x++, sX++, dX++) { pixel = src.getPixel(sX, sY, pixel); for (int r=0; r < nrows; r++) { accum = 0.f; for (int c=0; c < ncols; c++) { accum += matrix[r][c]*pixel[c]; } dstPixel[r] = (int) accum; } dst.setPixel(dX, dY, dstPixel); } } } else { // Need to add constant for (int y=0; y < src.getHeight(); y++, sY++, dY++) { dX = dminX; sX = sminX; for (int x=0; x < src.getWidth(); x++, sX++, dX++) { pixel = src.getPixel(sX, sY, pixel); for (int r=0; r < nrows; r++) { accum = 0.f; for (int c=0; c < nBands; c++) { accum += matrix[r][c]*pixel[c]; } dstPixel[r] = (int) (accum+matrix[r][nBands]); } dst.setPixel(dX, dY, dstPixel); } } } return dst; } Transforms the Raster using the matrix specified in the constructor. An IllegalArgumentException may be thrown if the number of bands in the source or destination is incompatible with the matrix. See the class comments for more details. If the destination is null, it will be created with a number of bands equalling the number of rows in the matrix. No exception is thrown if the operation causes a data overflow.
public final Rectangle2D getBounds2D(Raster src) { return src.getBounds(); } Returns the bounding box of the transformed destination. Since this is not a geometric operation, the bounding box is the same for the source and destination. An IllegalArgumentException may be thrown if the number of bands in the source is incompatible with the matrix. See the class comments for more details.
public final float[][] getMatrix() { float[][] ret = new float[nrows][]; for (int i = 0; i < nrows; i++) { ret[i] = Arrays.copyOf(matrix[i], ncols); } return ret; } Returns a copy of the linear combination matrix.
public final Point2D getPoint2D(Point2D srcPt, Point2D dstPt) { if (dstPt == null) { dstPt = new Point2D.Float(); } dstPt.setLocation(srcPt.getX(), srcPt.getY()); return dstPt; } Returns the location of the corresponding destination point given a point in the source Raster. If dstPt is specified, it is used to hold the return value. Since this is not a geometric operation, the point returned is the same as the specified srcPt.
public final RenderingHints getRenderingHints() { return hints; } Returns the rendering hints for this operation.