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/* Copyright (c) 2014, David A. Clunie DBA Pixelmed Publishing. All rights reserved. */
package com.pixelmed.codec.jpeg;
import java.util.Map;
/**
* <p>A JPEG DQT Marker Segment.</p>
*
* @author dclunie
*/
public class MarkerSegmentDQT {
private static final String identString = "@(#) $Header: /userland/cvs/codec/com/pixelmed/codec/jpeg/MarkerSegmentDQT.java,v 1.2 2014/03/21 21:46:20 dclunie Exp $";
private int nTables;
private int[] QuantizationTableElementPrecision;
private int[] QuantizationTableIdentifier;
private int[][] QuantizationTableElement;
public MarkerSegmentDQT(byte[] b,int length) throws Exception {
QuantizationTableElementPrecision = new int [4];
QuantizationTableIdentifier = new int [4];
QuantizationTableElement = new int [4][];
nTables=0;
int offset=0;
while (length > 0) {
if (nTables >= 4) {
throw new Exception("Only 4 tables are permitted");
}
QuantizationTableElementPrecision[nTables] = Utilities.extract8(b,offset) >> 4;
QuantizationTableIdentifier[nTables] = Utilities.extract8(b,offset) & 0x0f;
QuantizationTableElement[nTables] = new int[64];
++offset; --length;
for (int i=0; i<64; ++i) {
if (QuantizationTableElementPrecision[nTables] > 0) {
QuantizationTableElement[nTables][i] = Utilities.extract16be(b,offset);
offset+=2; length-=2;
}
else {
QuantizationTableElement[nTables][i] = Utilities.extract8(b,offset);
++offset; --length;
}
}
++nTables;
}
}
public void addToMapByIdentifier(Map<String,QuantizationTable> qtByIdentifer) {
for (int t=0; t<nTables; ++t) {
int id = QuantizationTableIdentifier[t];
String key = Integer.toString(id);
qtByIdentifer.put(key,new QuantizationTable(id,QuantizationTableElementPrecision[t],QuantizationTableElement[t]));
}
}
public String toString() {
StringBuffer buf = new StringBuffer();
buf.append("\n\tDQT:\n");
for (int t=0; t<nTables; ++t) {
buf.append("\t\t QuantizationTableElementPrecision = "+QuantizationTableElementPrecision[t]+"\n");
buf.append("\t\t QuantizationTableIdentifier = " +QuantizationTableIdentifier[t]+"\n");
for (int i=0; i<64; ++i) {
buf.append("\t\t\t QuantizationTableElement "+i+" = "+QuantizationTableElement[t][i]+"\n");
}
}
return buf.toString();
}
}
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