JPEGQTable (Java SE 23 & JDK 23)
Description: declaration: module: java.desktop, package: javax.imageio.plugins.jpeg, class: JPEGQTable
Keywords: javax.imageio.plugins.jpeg.JPEGQTable class

# 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
  Description
  `static final JPEGQTable`
  `K1Div2Luminance`
  The sample luminance quantization table given in the JPEG specification, table K.1, with all elements divided by 2.
  `static final JPEGQTable`
  `K1Luminance`
  The sample luminance quantization table given in the JPEG specification, table K.1.
  `static final JPEGQTable`
  `K2Chrominance`
  The sample chrominance quantization table given in the JPEG specification, table K.2.
  `static final 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
  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

  Modifier and Type
  Method
  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 declared in class java.lang.Object

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

- ## Field Details

  - ### 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 Details

  - ### 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 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 Details

  - ### 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.