javax.imageio.plugins.jpeg

## Class JPEGQTable

- java.lang.Object
- - javax.imageio.plugins.jpeg.JPEGQTable

-     public class JPEGQTable
      extends Object

  A class encapsulating a single JPEG quantization table. The elements appear in natural order (as opposed to zig-zag order). Static variables are provided for the "standard" tables taken from Annex K of the JPEG specification, as well as the default tables conventionally used for visually lossless encoding.

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

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static JPEGQTable` | `K1Div2Luminance` The sample luminance quantization table given in the JPEG specification, table K.1, with all elements divided by 2.
    `static JPEGQTable` | `K1Luminance` The sample luminance quantization table given in the JPEG specification, table K.1.
    `static JPEGQTable` | `K2Chrominance` The sample chrominance quantization table given in the JPEG specification, table K.2.
    `static JPEGQTable` | `K2Div2Chrominance` The sample chrominance quantization table given in the JPEG specification, table K.1, with all elements divided by 2.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `JPEGQTable(int[] table)` Constructs a quantization table from the argument, which must contain 64 elements in natural order (not zig-zag order).

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `JPEGQTable` | `getScaledInstance(float scaleFactor, boolean forceBaseline)` Returns a new quantization table where the values are multiplied by `scaleFactor` and then clamped to the range 1..32767 (or to 1..255 if `forceBaseline` is true).
    `int[]` | `getTable()` Returns a copy of the current quantization table as an array of `int`s in natural (not zig-zag) order.
    `String` | `toString()` Returns a `String` representing this quantization table.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### K1Luminance

          public static final JPEGQTable K1Luminance

      The sample luminance quantization table given in the JPEG specification, table K.1. According to the specification, these values produce "good" quality output.
      See Also:
        `K1Div2Luminance`

    - #### K1Div2Luminance

          public static final JPEGQTable K1Div2Luminance

      The sample luminance quantization table given in the JPEG specification, table K.1, with all elements divided by 2. According to the specification, these values produce "very good" quality output. This is the table usually used for "visually lossless" encoding, and is the default luminance table used if the default tables and quality settings are used.
      See Also:
        `K1Luminance`

    - #### K2Chrominance

          public static final JPEGQTable K2Chrominance

      The sample chrominance quantization table given in the JPEG specification, table K.2. According to the specification, these values produce "good" quality output.
      See Also:
        `K2Div2Chrominance`

    - #### K2Div2Chrominance

          public static final JPEGQTable K2Div2Chrominance

      The sample chrominance quantization table given in the JPEG specification, table K.1, with all elements divided by 2. According to the specification, these values produce "very good" quality output. This is the table usually used for "visually lossless" encoding, and is the default chrominance table used if the default tables and quality settings are used.
      See Also:
        `K2Chrominance`

  - ### Constructor Detail

    - #### JPEGQTable

          public JPEGQTable(int[] table)

      Constructs a quantization table from the argument, which must contain 64 elements in natural order (not zig-zag order). A copy is made of the the input array.
      Parameters:
        `table` - the quantization table, as an `int` array.
      Throws:
        `IllegalArgumentException` - if `table` is `null` or `table.length` is not equal to 64.

  - ### Method Detail

    - #### getTable

          public int[] getTable()

      Returns a copy of the current quantization table as an array of `int`s in natural (not zig-zag) order.
      Returns:
        A copy of the current quantization table.

    - #### getScaledInstance

          public JPEGQTable getScaledInstance(float scaleFactor,
                                              boolean forceBaseline)

      Returns a new quantization table where the values are multiplied by `scaleFactor` and then clamped to the range 1..32767 (or to 1..255 if `forceBaseline` is true).

      Values of `scaleFactor` less than 1 tend to improve the quality level of the table, and values greater than 1.0 degrade the quality level of the table.

      Parameters:
        `scaleFactor` - multiplication factor for the table.
        `forceBaseline` - if `true`, the values will be clamped to the range 1..255
      Returns:
        a new quantization table that is a linear multiple of the current table.

    - #### toString

          public String toString()

      Returns a `String` representing this quantization table.
      Overrides:
        `toString` in class `Object`
      Returns:
        a `String` representing this quantization table.

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