/*
* Gray8Lookup.java
*
* Created on September 9, 2006, 2:52 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 applies a lookup table to an image. The lookup table
* can be supplied through the constructor or by the setTable procedure.
* This pipeline stage modifies its input.
*
* @author webb
*/
public class Gray8Lookup extends PipelineStage {
private byte[] table;
/**
* Creates a new instance of Gray8Lookup.
* @param table The mapping table. Element i maps gray value Byte.MinValue + i to table[i].
* @throws jjil.core.Error when table is not a 256-element array.
*/
public Gray8Lookup(byte[] table) throws jjil.core.Error {
setTable(table);
}
/**
* Return the lookup table currently being used.
* @return the lookup table.
*/
public byte[] getTable() {
byte[] result = new byte[256];
System.arraycopy(this.table, 0, result, 0, this.table.length);
return result;
}
/**
* Maps input Gray8Image through the lookup table, replacing values in the image.
* @param image the input image (output replaces input).
* @throws jjil.core.Error if image is not a Gray8Image.
*/
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);
}
Gray8Image input = (Gray8Image) image;
byte[] data = input.getData();
for (int i=0; i<data.length; i++) {
data[i] = this.table[data[i]+128];
}
super.setOutput(input);
}
/**
* Assign a new lookup table. Images passed to push() after setTable is called
* will be mapped by the new image.
* @param table The lookup table. Input image value g is mapped to table[g + Byte.MinValue]
* @throws jjil.core.Error if table is not a 256-element array.
*/
public void setTable(byte[] table) throws jjil.core.Error {
if (table.length != 256) {
throw new Error(
Error.PACKAGE.ALGORITHM,
ErrorCodes.LOOKUP_TABLE_LENGTH_NOT_256,
table.toString(),
null,
null);
}
this.table = new byte[256];
System.arraycopy(table, 0, this.table, 0, this.table.length);
}
}