1. /*
  2. * @(#)JPEGHuffmanTable.java 1.7 00/02/02
  3. *
  4. * Copyright 1998-2000 Sun Microsystems, Inc. All Rights Reserved.
  5. *
  6. * This software is the proprietary information of Sun Microsystems, Inc.
  7. * Use is subject to license terms.
  8. *
  9. */
  10. /**********************************************************************
  11. **********************************************************************
  12. **********************************************************************
  13. *** COPYRIGHT (c) 1997-1998 Eastman Kodak Company. ***
  14. *** As an unpublished work pursuant to Title 17 of the United ***
  15. *** States Code. All rights reserved. ***
  16. **********************************************************************
  17. **********************************************************************
  18. **********************************************************************/
  19. package com.sun.image.codec.jpeg;
  20. /** A class to encapsulate a JPEG Huffman table.
  21. * <p>
  22. * Note that the classes in the com.sun.image.codec.jpeg package are not
  23. * part of the core Java APIs. They are a part of Sun's JDK and JRE
  24. * distributions. Although other licensees may choose to distribute these
  25. * classes, developers cannot depend on their availability in non-Sun
  26. * implementations. We expect that equivalent functionality will eventually
  27. * be available in a core API or standard extension.
  28. * <p>
  29. */
  30. public class JPEGHuffmanTable {
  31. /**
  32. * The maximum number of symbol lengths
  33. * (max symbol length in bits = 16)
  34. */
  35. private static final int HUFF_MAX_LEN=17;
  36. /** the maximum number of symbols */
  37. private static final int HUFF_MAX_SYM=256;
  38. /** bits[k] = number of symbols with length k bits */
  39. private short lengths[];
  40. /** Symbols in order of increasing length */
  41. private short symbols[];
  42. /** Standard Huffman table ( JPEG standard section K.3 ) */
  43. public static final JPEGHuffmanTable StdDCLuminance =
  44. new JPEGHuffmanTable();
  45. static {
  46. short lengths[] = { // 0-base
  47. 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
  48. short symbols[] = {
  49. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
  50. StdDCLuminance.lengths = lengths;
  51. StdDCLuminance.symbols = symbols;
  52. StdDCLuminance.checkTable();
  53. }
  54. /** Standard Huffman table ( JPEG standard section K.3 ) */
  55. public static final JPEGHuffmanTable StdDCChrominance =
  56. new JPEGHuffmanTable();
  57. static {
  58. short lengths[] = { // 0-base
  59. 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
  60. short symbols[] = {
  61. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
  62. StdDCChrominance.lengths = lengths;
  63. StdDCChrominance.symbols = symbols;
  64. StdDCChrominance.checkTable();
  65. }
  66. /** Standard Huffman table ( JPEG standard section K.3 ) */
  67. public static final JPEGHuffmanTable StdACLuminance =
  68. new JPEGHuffmanTable();
  69. static {
  70. short lengths[] = { // 0-base
  71. 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
  72. short symbols[] = {
  73. 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
  74. 0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
  75. 0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
  76. 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
  77. 0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
  78. 0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
  79. 0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
  80. 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
  81. 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
  82. 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
  83. 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
  84. 0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
  85. 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
  86. 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
  87. 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
  88. 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
  89. 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
  90. 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
  91. 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
  92. 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
  93. 0xf9, 0xfa };
  94. StdACLuminance.lengths = lengths;
  95. StdACLuminance.symbols = symbols;
  96. StdACLuminance.checkTable();
  97. }
  98. /** Standard Huffman table ( JPEG standard section K.3 ) */
  99. public static final JPEGHuffmanTable StdACChrominance =
  100. new JPEGHuffmanTable();
  101. static {
  102. short lengths[] = { // 0-base
  103. 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
  104. short symbols[] = {
  105. 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
  106. 0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
  107. 0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
  108. 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
  109. 0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
  110. 0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
  111. 0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
  112. 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
  113. 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
  114. 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
  115. 0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
  116. 0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
  117. 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
  118. 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
  119. 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
  120. 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
  121. 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
  122. 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
  123. 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
  124. 0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
  125. 0xf9, 0xfa };
  126. StdACChrominance.lengths = lengths;
  127. StdACChrominance.symbols = symbols;
  128. StdACChrominance.checkTable();
  129. }
  130. /**
  131. * Private constructor used to construct the Standard Huffman tables
  132. */
  133. private JPEGHuffmanTable() {
  134. lengths = null;
  135. symbols = null;
  136. }
  137. /**
  138. * Creates a Huffman Table and initializes it.
  139. * @param lengths lengths[k] = # of symbols with codes of length k
  140. * bits; lengths[0] is ignored
  141. * @param symbols symbols in order of increasing code length
  142. * @exception IllegalArgumentException if the length of
  143. * <code>lengths</code> is greater than 17
  144. * @exception IllegalArgumentException if the length of
  145. * <code>symbols</code> is greater than 256
  146. * @exception IllegalArgumentException if any of the values in
  147. * <code>lengths</code> or <code>symbols</code> is less than zero
  148. */
  149. public JPEGHuffmanTable( short lengths[], short symbols[] ) {
  150. if ( lengths.length > HUFF_MAX_LEN )
  151. throw new IllegalArgumentException( "lengths array is too long" );
  152. for (int i=1; i < lengths.length; i++)
  153. if (lengths[i] < 0)
  154. throw new IllegalArgumentException
  155. ( "Values in lengths array must be non-negative." );
  156. if ( symbols.length > HUFF_MAX_SYM )
  157. throw new IllegalArgumentException( "symbols array is too long" );
  158. for (int i=0; i < symbols.length; i++)
  159. if (symbols[i] < 0)
  160. throw new IllegalArgumentException
  161. ( "Values in symbols array must be non-negative." );
  162. this.lengths = new short[lengths.length];
  163. this.symbols = new short[symbols.length];
  164. System.arraycopy( lengths, 0, this.lengths, 0, lengths.length );
  165. System.arraycopy( symbols, 0, this.symbols, 0, symbols.length );
  166. checkTable();
  167. }
  168. /**
  169. * This checks that the table they gave us isn't 'illegal' It
  170. * checks that the symbol length counts are possible, and that
  171. * they gave us at least enough symbols for the symbol length
  172. * counts. Eventually this might check that there aren't duplicate
  173. * symbols.
  174. */
  175. private void checkTable() {
  176. int numVals=2;
  177. int sum=0;
  178. for (int i=1; i<lengths.length; i++) {
  179. sum += lengths[i];
  180. numVals -= lengths[i];
  181. numVals *= 2;
  182. }
  183. //System.out.println("NumVals: " + numVals);
  184. //System.out.println("Sum: " + sum + " Symbols: " + symbols.length);
  185. if (numVals < 0)
  186. throw new IllegalArgumentException
  187. ("Invalid Huffman Table provided, lengths are incorrect.");
  188. // I'll let them go if they gave us 'extra' symbols...
  189. if (sum > symbols.length)
  190. throw new IllegalArgumentException
  191. ("Invalid Huffman Table provided, not enough symbols.");
  192. }
  193. /**
  194. * Return a copy of the array containing the number of symbols
  195. * for each length in the Huffman table.
  196. * @return A short array where array[k] = # of symbols in the
  197. * table of length k. array[0] is unused
  198. */
  199. public short[] getLengths() {
  200. short[] ret = new short[ lengths.length];
  201. System.arraycopy( lengths, 0, ret, 0, lengths.length);
  202. return ret;
  203. }
  204. /**
  205. * Return an array containing the Huffman symbols arranged by
  206. * increasing length. To make use of this array you must refer
  207. * the the lengths array.
  208. * @return A short array of Huffman symbols
  209. */
  210. public short[] getSymbols() {
  211. short[] ret = new short[symbols.length];
  212. System.arraycopy( symbols, 0, ret, 0, symbols.length);
  213. return ret;
  214. }
  215. }