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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @author Rustem V. Rafikov
* @version $Revision: 1.3 $
*/
package javax.imageio.plugins.jpeg;
/**
* The JPEGQTable class represents a single JPEG quantization table and provides
* for the standard tables taken from the JPEG specification.
*
* @since Android 1.0
*/
public class JPEGQTable {
/**
* The Constant SIZE.
*/
private final static int SIZE = 64;
/**
* The Constant BASELINE_MAX.
*/
private final static int BASELINE_MAX = 255;
/**
* The Constant MAX.
*/
private final static int MAX = 32767;
/**
* The table.
*/
private int[] theTable;
/*
* K1 & K2 tables can be found in the JPEG format specification at
* http://www.w3.org/Graphics/JPEG/itu-t81.pdf
*/
/**
* The Constant K1LumTable.
*/
private static final int[] K1LumTable = new int[] {
16, 11, 10, 16, 24, 40, 51, 61, 12, 12, 14, 19, 26, 58, 60, 55, 14, 13, 16, 24, 40, 57,
69, 56, 14, 17, 22, 29, 51, 87, 80, 62, 18, 22, 37, 56, 68, 109, 103, 77, 24, 35, 55,
64, 81, 104, 113, 92, 49, 64, 78, 87, 103, 121, 120, 101, 72, 92, 95, 98, 112, 100,
103, 99
};
/**
* The Constant K2ChrTable.
*/
private static final int[] K2ChrTable = new int[] {
17, 18, 24, 47, 99, 99, 99, 99, 18, 21, 26, 66, 99, 99, 99, 99, 24, 26, 56, 99, 99, 99,
99, 99, 47, 66, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99
};
/**
* The K1Luminance indicates standard table K.1 from JPEG specification and
* produces "good" quality output.
*/
public static final JPEGQTable K1Luminance = new JPEGQTable(K1LumTable);
/**
* The K1Div2Luminance indicates K.1 table from JPEG specification with all
* elements divided by 2 and produces "very good" quality output.
*/
public static final JPEGQTable K1Div2Luminance = K1Luminance.getScaledInstance(0.5f, true);
/**
* The K2Chrominance indicates K.2 table from JPEG specification and
* produces "good" quality output.
*/
public static final JPEGQTable K2Chrominance = new JPEGQTable(K2ChrTable);
/**
* The Constant K2Div2Chrominance indicates K.2 table from JPEG
* specification with all elements divided by 2 and produces "very good"
* quality output.
*/
public static final JPEGQTable K2Div2Chrominance = K2Chrominance.getScaledInstance(0.5f, true);;
/**
* Instantiates a new JPEGQTable from the array, which should contain 64
* elements in natural order.
*
* @param table
* the quantization table.
*/
public JPEGQTable(int[] table) {
if (table == null) {
throw new IllegalArgumentException("table should not be NULL");
}
if (table.length != SIZE) {
throw new IllegalArgumentException("illegal table size: " + table.length);
}
theTable = table.clone();
}
/**
* Gets the current quantization table as an array of integer values.
*
* @return the current quantization table as an array of integer values.
*/
public int[] getTable() {
return theTable.clone();
}
/**
* Gets the scaled instance as quantization table where the values are
* multiplied by the scaleFactor and then clamped if forceBaseline is true.
*
* @param scaleFactor
* the scale factor of table.
* @param forceBaseline
* the force baseline flag, the values should be clamped if true.
* @return the new quantization table.
*/
public JPEGQTable getScaledInstance(float scaleFactor, boolean forceBaseline) {
int table[] = new int[SIZE];
int maxValue = forceBaseline ? BASELINE_MAX : MAX;
for (int i = 0; i < theTable.length; i++) {
int rounded = Math.round(theTable[i] * scaleFactor);
if (rounded < 1) {
rounded = 1;
}
if (rounded > maxValue) {
rounded = maxValue;
}
table[i] = rounded;
}
return new JPEGQTable(table);
}
/**
* Returns the string representation of this JPEGQTable object.
*
* @return the string representation of this JPEGQTable object.
*/
@Override
public String toString() {
// -- TODO more informative info
return "JPEGQTable";
}
}
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