com.twelvemonkeys.imageio.metadata.jpeg

Class JPEGQuality

java.lang.Object

com.twelvemonkeys.imageio.metadata.jpeg.JPEGQuality

public final class JPEGQuality
extends java.lang.Object

Determines an approximate JPEG compression quality value from the quantization tables.

Version:

$Id: JPEGQuality.java,v 1.0 16.02.12 17:07 haraldk Exp$

Author:

Harald Kuhr, last modified by $Author: haraldk$

Constructor Summary

Constructors

Constructor and Description
JPEGQuality()

Method Summary

Methods

Modifier and Type	Method and Description
static float	getJPEGQuality(javax.imageio.stream.ImageInputStream input) Determines an approximate JPEG compression quality value from the quantization tables.
static float	getJPEGQuality(java.util.List<JPEGSegment> segments) Determines an approximate JPEG compression quality value from the quantization tables.
static javax.imageio.plugins.jpeg.JPEGQTable[]	getQTables(java.util.List<JPEGSegment> segments)
static void	main(java.lang.String[] args)

Methods inherited from class java.lang.Object

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

Constructor Detail

JPEGQuality

public JPEGQuality()

Method Detail

getJPEGQuality

public static float getJPEGQuality(java.util.List<JPEGSegment> segments)
                            throws java.io.IOException

Determines an approximate JPEG compression quality value from the quantization tables. The value will be in the range [0...1], where 1 is the best possible value.

Parameters:

segments - a list of JPEG segments containing the DQT quantization tables.

Returns:

a float in the range [0...1], representing the JPEG quality, or -1 if the quality can't be determined.

Throws:

javax.imageio.IIOException - if a JPEG format error is found during parsing.

java.io.IOException - if an I/O exception occurs during parsing.

See Also:

ImageWriteParam.setCompressionQuality(float), JPEG.DQT

getJPEGQuality

public static float getJPEGQuality(javax.imageio.stream.ImageInputStream input)
                            throws java.io.IOException

Determines an approximate JPEG compression quality value from the quantization tables. The value will be in the range [0...1], where 1 is the best possible value.

Parameters:

input - an image input stream containing JPEG data.

Returns:

a float in the range [0...1], representing the JPEG quality, or -1 if the quality can't be determined.

Throws:

javax.imageio.IIOException - if a JPEG format error is found during parsing.

java.io.IOException - if an I/O exception occurs during parsing.

See Also:

ImageWriteParam.setCompressionQuality(float), JPEG.DQT

getQTables

public static javax.imageio.plugins.jpeg.JPEGQTable[] getQTables(java.util.List<JPEGSegment> segments)
                                                          throws java.io.IOException

Throws:

java.io.IOException

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

Throws:

java.io.IOException