/*
* RgbShrink.java.
* Reduces a color image to a new size by averaging the pixels nearest each
* target pixel's pre-image. This is done by converting each band of the image
* into a gray image, shrinking them individually, then recombining them into
* an RgbImage
*
* Created on October 13, 2007, 2:21 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;
import jjil.core.RgbImage;
import jjil.core.Sequence;
/**
* Shrinks a color (RgbImage) to a given size. Each band is shrunk independently.
* The pixels that each pixel maps to are averaged. There is no between-target-pixel
* smoothing. The output image must be smaller than or equal to the size of the
* input.
* @author webb
*/
public class RgbShrink extends PipelineStage {
private int cHeight;
private int cWidth;
private Sequence seqR, seqG, seqB;
/** Creates a new instance of RgbShrink.
*
* @param cWidth new image width
* @param cHeight new image height
* @throws jjil.core.Error if either is less than or equal to zero.
*/
public RgbShrink(int cWidth, int cHeight)
throws jjil.core.Error {
setWidth(cWidth);
setHeight(cHeight);
setupPipeline();
}
/** Gets current target height
*
* @return current height
*/
public int getHeight() {
return this.cHeight;
}
/** Gets current target width
*
* @return current width
*/
public int getWidth() {
return this.cWidth;
}
/**
* Process an image.
* @param image the input RgbImage.
* @throws jjil.core.Error if the input is not an RgbImage, or is smaller than the target image either
* horizontally or vertically.
*/
public void push(Image image) throws jjil.core.Error {
if (!(image instanceof RgbImage)) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.IMAGE_NOT_RGBIMAGE,
image.toString(),
null,
null);
}
if (image.getWidth() < this.cWidth || image.getHeight() < this.cHeight) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.SHRINK_OUTPUT_LARGER_THAN_INPUT,
image.toString(),
this.toString(),
null);
}
/* shrink R band */
this.seqR.push(image);
/* shrink G band */
this.seqG.push(image);
/* shrink B band */
this.seqB.push(image);
/* recombine bands */
Gray3Bands2Rgb g3rgb = new Gray3Bands2Rgb();
super.setOutput(g3rgb.push(
(Gray8Image)this.seqR.getFront(),
(Gray8Image)this.seqG.getFront(),
(Gray8Image)this.seqB.getFront()));
}
/** Changes target height
*
* @param cHeight the new target height.
* @throws jjil.core.Error if height is not positive
*/
private void setHeight(int cHeight) throws jjil.core.Error {
if (cHeight <= 0) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.OUTPUT_IMAGE_SIZE_NEGATIVE,
new Integer(cHeight).toString(),
null,
null);
}
this.cHeight = cHeight;
}
private void setupPipeline() throws jjil.core.Error
{
RgbSelectGray sel = new RgbSelectGray(RgbSelectGray.RED);
this.seqR = new Sequence(sel);
Gray8Shrink gs = new Gray8Shrink(cWidth, cHeight);
this.seqR.add(gs);
sel = new RgbSelectGray(RgbSelectGray.GREEN);
this.seqG = new Sequence(sel);
gs = new Gray8Shrink(cWidth, cHeight);
this.seqG.add(gs);
sel = new RgbSelectGray(RgbSelectGray.BLUE);
this.seqB = new Sequence(sel);
gs = new Gray8Shrink(cWidth, cHeight);
this.seqB.add(gs);
}
/** Changes target width
*
* @param cWidth the new target width.
* @throws jjil.core.Error if height is not positive
*/
private void setWidth(int cWidth) throws jjil.core.Error {
if (cWidth <= 0) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.OUTPUT_IMAGE_SIZE_NEGATIVE,
new Integer(cWidth).toString(),
null,
null);
}
this.cWidth = cWidth;
}
/** Return a string describing the shrinking operation.
*
* @return the string describing the shrinking operation.
*/
public String toString() {
return super.toString() + " (" + this.cWidth + "," + this.cHeight + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
}
}