/*
* Gray8Reduce.java
*
* Created on September 2, 2006, 3:59 PM
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*
* Copyright 2007 by Jon A. Webb
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the Lesser GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package jjil.algorithm;
import jjil.core.Error;
import jjil.core.Gray8Image;
import jjil.core.Image;
import jjil.core.PipelineStage;
/**
* Pipeline stage reduces an image's size by rectangular averaging. The
* reduction factor must evenly divide the image size. No
* smoothing is done.
*
* @author webb
*/
public class Gray8Reduce extends PipelineStage {
private int cReduceHeight;
private int cReduceWidth;
/**
* Creates a new instance of Gray8Reduce.
* @param cReduceWidth amount to reduce the width by
* @param cReduceHeight amount to reduce the height by
* @throws jjil.core.Error if the reduce width or height is less than or equal to zero.
*/
public Gray8Reduce(int cReduceWidth, int cReduceHeight)
throws jjil.core.Error {
setReductionFactor(cReduceWidth, cReduceHeight);
}
/** Reduces a gray image by a factor horizontally and vertically through
* averaging. The reduction factor must be an even multiple of the image
* size.
*
* @param image the input image.
* @throws jjil.core.Error if the input image is not gray, or
* the reduction factor does not evenly divide the image size.
*/
public void push(Image image) throws jjil.core.Error {
if (!(image instanceof Gray8Image)) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.IMAGE_NOT_GRAY8IMAGE,
image.toString(),
null,
null);
}
if (image.getWidth() % this.cReduceWidth != 0) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.IMAGE_NOT_GRAY8IMAGE,
image.toString(),
null,
null);
}
if (image.getHeight() % this.cReduceHeight != 0) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.REDUCE_INPUT_IMAGE_NOT_MULTIPLE_OF_OUTPUT_SIZE,
image.toString(),
this.toString(),
null);
}
Gray8Image gray = (Gray8Image) image;
byte[] bIn = gray.getData();
int cReducedHeight = image.getHeight() / this.cReduceHeight;
int cReducedWidth = image.getWidth() / this.cReduceWidth;
Gray8Image result = new Gray8Image(cReducedWidth, cReducedHeight);
byte[] bOut = result.getData();
for (int i=0; i<cReducedHeight; i++) {
for (int j=0; j<cReducedWidth; j++) {
int sum = 0;
for (int k=0; k<this.cReduceHeight; k++) {
for (int l=0; l<this.cReduceWidth; l++) {
sum += bIn[(i*this.cReduceHeight+k) * image.getWidth() +
(j*this.cReduceWidth + l)];
}
}
bOut[i*cReducedWidth + j] =
(byte) (sum / (this.cReduceHeight * this.cReduceWidth));
}
}
super.setOutput(result);
}
/** Returns the height reduction factor.
*
* @return the height reduction factor.
*/
public int getHeightReduction()
{
return this.cReduceHeight;
}
/** Returns the width reduction factor.
*
* @return the width reduction factor.
*/
public int getWidthReduction()
{
return this.cReduceWidth;
}
/** Sets a new width, height reduction factor.
*
* @param cReduceWidth the amount by which to reduce the image width.
* @param cReduceHeight the amount by which to reduce the image height.
* @throws jjil.core.Error if either cReduceWidth or cReduceHeight
* is less than or equal to 0.
*/
public void setReductionFactor(int cReduceWidth, int cReduceHeight)
throws jjil.core.Error {
if (cReduceWidth <= 0 || cReduceHeight <= 0) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.OUTPUT_IMAGE_SIZE_NEGATIVE,
new Integer(cReduceWidth).toString(),
new Integer(cReduceHeight).toString(),
null);
}
this.cReduceWidth = cReduceWidth;
this.cReduceHeight = cReduceHeight;
}
/** Return a string describing the reduction operation.
*
* @return the string describing the reduction operation.
*/
public String toString() {
return super.toString() + " (" + this.cReduceWidth + "," + //$NON-NLS-1$ //$NON-NLS-2$
this.cReduceHeight + ")"; //$NON-NLS-1$
}
}