/*
* ReduceToBilevelThreshold
*
* Copyright (c) 2001, 2002, 2003 Marco Schmidt.
* All rights reserved.
*/
package net.sourceforge.jiu.color.reduction;
import net.sourceforge.jiu.data.BilevelImage;
import net.sourceforge.jiu.data.GrayIntegerImage;
import net.sourceforge.jiu.data.MemoryBilevelImage;
import net.sourceforge.jiu.data.PixelImage;
import net.sourceforge.jiu.ops.ImageToImageOperation;
import net.sourceforge.jiu.ops.MissingParameterException;
import net.sourceforge.jiu.ops.WrongParameterException;
/**
* Reduces a {@link net.sourceforge.jiu.data.GrayIntegerImage} to a
* {@link net.sourceforge.jiu.data.BilevelImage} by setting all values below
* a certain threshold value to black and everything else to white.
* <h3>Default value</h3>
* If no threshold is specified via {@link #setThreshold(int)}, this operation
* uses a default value of ({@link net.sourceforge.jiu.data.IntegerImage#getMaxSample(int)} + 1) / 2.
* <h3>Usage example</h3>
* This example sets all values below 33 percent luminance to black,
* everything else to white.
* <pre>
* GrayIntegerImage image = ...;
* ReduceToBilevelThreshold red = new ReduceToBilevelThreshold();
* red.setInputImage(image);
* red.setThreshold(image.getMaxSample(0) / 3);
* red.process();
* BilevelImage reducedImage= (BilevelImage)red.getOutputImage();
* </pre>
* @author Marco Schmidt
*/
public class ReduceToBilevelThreshold extends ImageToImageOperation
{
private Integer threshold;
/**
* Returns the current threshold value, or <code>null</code> if
* none was specified and the operation's process method was not
* run yet.
* @return threshold value
*/
public Integer getThreshold()
{
return threshold;
}
private void process(GrayIntegerImage in, BilevelImage out) throws WrongParameterException
{
final int MAX_SAMPLE = in.getMaxSample(0);
if (threshold == null)
{
threshold = new Integer((MAX_SAMPLE + 1) / 2);
}
final int THRESHOLD = threshold.intValue();
if (THRESHOLD > MAX_SAMPLE)
{
throw new WrongParameterException("Threshold must be smaller than or equal to the maximum sample of the input image.");
}
final int WIDTH = in.getWidth();
final int HEIGHT = in.getHeight();
out.clear(BilevelImage.BLACK);
for (int y = 0; y < HEIGHT; y++)
{
for (int x = 0; x < WIDTH; x++)
{
if (in.getSample(0, x, y) >= THRESHOLD)
{
out.putWhite(x, y);
}
}
setProgress(y, HEIGHT);
}
}
public void process() throws
MissingParameterException,
WrongParameterException
{
PixelImage in = getInputImage();
if (in == null)
{
throw new MissingParameterException("Input image missing.");
}
if (!(in instanceof GrayIntegerImage))
{
throw new WrongParameterException("Input image must implement GrayIntegerImage.");
}
PixelImage out = getOutputImage();
if (out == null)
{
out = new MemoryBilevelImage(in.getWidth(), in.getHeight());
setOutputImage(out);
}
if (out != null && !(out instanceof BilevelImage))
{
throw new WrongParameterException("Output image must implement BilevelImage.");
}
if (out != null && (in.getWidth() != out.getWidth() || in.getHeight() != out.getHeight()))
{
throw new WrongParameterException("Input and output images must have the same resolution.");
}
process((GrayIntegerImage)in, (BilevelImage)out);
}
/**
* Sets a new threshold value.
* @param newThreshold the new threshold value to be used for this operation
* @throws IllegalArgumentException if the threshold value is negative
*/
public void setThreshold(int newThreshold)
{
if (newThreshold < 0)
{
throw new IllegalArgumentException("New threshold value must be 0 or larger.");
}
threshold = new Integer(newThreshold);
}
}