javax.imageio.plugins.jpeg

Class JPEGHuffmanTable


  • public class JPEGHuffmanTable
extends Object
    A class encapsulating a single JPEG Huffman table. Fields are provided for the "standard" tables taken from Annex K of the JPEG specification. These are the tables used as defaults.

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

    • Field Detail

      • StdDCLuminance

        public static final JPEGHuffmanTable StdDCLuminance
        The standard DC luminance Huffman table.

      • StdDCChrominance

        public static final JPEGHuffmanTable StdDCChrominance
        The standard DC chrominance Huffman table.

      • StdACLuminance

        public static final JPEGHuffmanTable StdACLuminance
        The standard AC luminance Huffman table.

      • StdACChrominance

        public static final JPEGHuffmanTable StdACChrominance
        The standard AC chrominance Huffman table.

    • Constructor Detail

      • 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.
        Throws:
        IllegalArgumentException - if lengths or values are null, the length of lengths is greater than 16, the length of values is greater than 256, if any value in lengths or values is less than zero, or if the arrays do not describe a valid Huffman table.

    • Method Detail

      • getLengths

        public short[] getLengths()
        Returns 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.
        See Also:
        getValues()

      • getValues

        public short[] getValues()
        Returns 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.
        See Also:
        getLengths()

      • toString

        public String toString()
        Returns a String representing this Huffman table.
        Overrides:
        toString in class  Object
        Returns:
        a String representing this Huffman table.