| java.lang.Object | |
| ↳ | javax.imageio.plugins.jpeg.JPEGQTable |
Class Overview
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
Summary
| Fields | |||||||||||
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| K1Div2Luminance | The sample luminance quantization table given in the JPEG specification, table K.1, with all elements divided by 2. | ||||||||||
| K1Luminance | The sample luminance quantization table given in the JPEG specification, table K.1. | ||||||||||
| K2Chrominance | The sample chrominance quantization table given in the JPEG specification, table K.2. | ||||||||||
| K2Div2Chrominance | The sample chrominance quantization table given in the JPEG specification, table K.1, with all elements divided by 2. | ||||||||||
| Public Constructors | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Constructs a quantization table from the argument, which must
contain 64 elements in natural order (not zig-zag order).
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| Public Methods | |||||||||||
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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). | |||||||||||
Returns a copy of the current quantization table as an array
of
ints in natural (not zig-zag) order. | |||||||||||
Returns a
String representing this quantization table. | |||||||||||
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Inherited Methods | |||||||||||
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From class
java.lang.Object
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Fields
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
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
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
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
Public Constructors
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.
|
|---|
Public Methods
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.
public int[] getTable ()
Returns a copy of the current quantization table as an array
of ints in natural (not zig-zag) order.
Returns
- A copy of the current quantization table.
public String toString ()
Returns a String representing this quantization table.
Returns
- a
Stringrepresenting this quantization table.