javax.imageio.plugins.jpeg

Class JPEGQTable

java.lang.Object

javax.imageio.plugins.jpeg.JPEGQTable

public class JPEGQTable
extends Object

The JPEGQTable class represents a quantization table that can be used to encode or decode a JPEG stream. The standard JPEG luminance and chrominance quantization tables are provided as static fields. Table entries are stored in natural order, not zig-zag order.

Field Summary

Fields

Modifier and Type	Field and Description
static JPEGQTable	K1Div2Luminance The standard JPEG luminance quantization table, scaled by one-half.
static JPEGQTable	K1Luminance The standard JPEG luminance quantization table.
static JPEGQTable	K2Chrominance The standard JPEG chrominance quantization table.
static JPEGQTable	K2Div2Chrominance The standard JPEG chrominance quantization table, scaled by one-half.

Constructor Summary

Constructors

Constructor and Description
JPEGQTable(int[] table) Construct a new JPEG quantization table.

Method Summary

Methods

Modifier and Type	Method and Description
JPEGQTable	getScaledInstance(float scaleFactor, boolean forceBaseline) Retrieve a copy of this JPEG quantization table with every value scaled by the given scale factor, and clamped from 1 to 255 baseline or from 1 to 32767 otherwise.
int[]	getTable() Retrieve a copy of the quantization values for this table.
String	toString() Create a string representing this JPEG 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 standard JPEG luminance quantization table. Values are stored in natural order.

K1Div2Luminance

public static final JPEGQTable K1Div2Luminance

The standard JPEG luminance quantization table, scaled by one-half. Values are stored in natural order.

K2Chrominance

public static final JPEGQTable K2Chrominance

The standard JPEG chrominance quantization table. Values are stored in natural order.

K2Div2Chrominance

public static final JPEGQTable K2Div2Chrominance

The standard JPEG chrominance quantization table, scaled by one-half. Values are stored in natural order.

Constructor Detail

JPEGQTable

public JPEGQTable(int[] table)

Construct a new JPEG quantization table. A copy is created of the table argument.

Parameters:

table - the 64-element value table, stored in natural order

Throws:

IllegalArgumentException - if the table is null or if table's length is not equal to 64.

Method Detail

getTable

public int[] getTable()

Retrieve a copy of the quantization values for this table.

Returns:

a copy of the quantization value array

getScaledInstance

public JPEGQTable getScaledInstance(float scaleFactor,
                           boolean forceBaseline)

Retrieve a copy of this JPEG quantization table with every value scaled by the given scale factor, and clamped from 1 to 255 baseline or from 1 to 32767 otherwise.

Parameters:

scaleFactor - the factor by which to scale this table

forceBaseline - clamp scaled values to a maximum of 255 if true, 32767 if false

Returns:

a new scaled JPEG quantization table

toString

public String toString()

Create a string representing this JPEG quantization table.

Overrides:

toString in class Object

Returns:

the String representing this Object, which may be null

See Also:

Object.getClass(), Object.hashCode(), Class.getName(), Integer.toHexString(int)