javax.imageio.plugins.jpeg
class JPEGHuffmanTable

java.lang.Object javax.imageio.plugins.jpeg.JPEGHuffmanTable

public class JPEGHuffmanTable
extends Object

A class encapsulating a single JPEG Huffman table. Fields are provided for the "standard" tables from taken from Annex K of the JPEG specification. These are the tables used as defaults. This class differs from the old unsupported com.sun.image.codec.jpeg.JPEGHuffmanTable in two ways:

1. The lengths arrays for this class do not contain an ignored 0th entry. The lengths array in a JPEG stream does not contain an extra entry, and this class is used to represent the contents of a JPEG stream.
2. The old class incorrectly referred to Huffman "symbols", while expecting an array of values to be encoded. This class has a getValues method instead of a getSymbols method.

For more information about the operation of the built-in JPEG plug-ins, see the JPEG metadata format specification and usage notes.

StdACChrominance

public static final JPEGHuffmanTable StdACChrominance

The standard AC chrominance Huffman table.

StdACLuminance

public static final JPEGHuffmanTable StdACLuminance

The standard AC luminance Huffman table.

StdDCChrominance

public static final JPEGHuffmanTable StdDCChrominance

The standard DC chrominance Huffman table.

StdDCLuminance

public static final JPEGHuffmanTable StdDCLuminance

The standard DC luminance Huffman table.

JPEGHuffmanTable

public JPEGHuffmanTable(short[] lengths,
                        short[] values)

Creates a Huffman table and initializes it. The input arrays are copied. The arrays must describe a possible Huffman table. For example, 3 codes cannot be expressed with a single bit.

Parameters:

lengths - an array of shorts where lengths[k] is equal to the number of values with corresponding codes of length k + 1 bits.

values - an array of shorts containing the values in order of increasing code length.

getLengths

public short[] getLengths()

Return an array of shorts containing the number of values for each length in the Huffman table. The returned array is a copy.

Returns:

a short array where array[k-1] is equal to the number of values in the table of length k.

getValues

public short[] getValues()

Return an array of shorts containing the values arranged by increasing length of their corresponding codes. The interpretation of the array is dependent on the values returned from getLengths. The returned array is a copy.

Returns:

a short array of values.

toString

public String toString()

Overrides:

toString in class Object