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/*
* 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 .
*
*/
package com.github.ojil.algorithm;
import com.github.ojil.core.Gray8Image;
import com.github.ojil.core.Image;
import com.github.ojil.core.ImageError;
import com.github.ojil.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 ImageError
* when table is not a 256-element array.
*/
public Gray8Lookup(final Byte[] table) throws ImageError {
setTable(table);
}
/**
* Return the lookup table currently being used.
*
* @return the lookup table.
*/
public Byte[] getTable() {
final Byte[] result = new Byte[256];
System.arraycopy(table, 0, result, 0, 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 ImageError
* if image is not a Gray8Image.
*/
@Override
public void push(final Image> image) throws ImageError {
if (!(image instanceof Gray8Image)) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.IMAGE_NOT_GRAY8IMAGE, image.toString(), null, null);
}
final Gray8Image> input = (Gray8Image>) image;
final Byte[] data = input.getData();
for (int i = 0; i < data.length; i++) {
data[i] = 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 ImageError
* if table is not a 256-element array.
*/
public void setTable(final Byte[] table) throws ImageError {
if (table.length != 256) {
throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.LOOKUP_TABLE_LENGTH_NOT_256, table.toString(), null, null);
}
this.table = new Byte[256];
System.arraycopy(table, 0, this.table, 0, this.table.length);
}
}
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