com.twelvemonkeys.imageio.metadata.jpeg

Class JPEGQuality

java.lang.Object

com.twelvemonkeys.imageio.metadata.jpeg.JPEGQuality

public final class JPEGQuality
extends 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

Modifier and Type	Method and Description
static float	getJPEGQuality(ImageInputStream input) Determines an approximate JPEG compression quality value from the quantization tables.
static float	getJPEGQuality(List<JPEGSegment> segments) Determines an approximate JPEG compression quality value from the quantization tables.
static JPEGQTable[]	getQTables(List<JPEGSegment> segments)
static void	main(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(List<JPEGSegment> segments)
                            throws 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:

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

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

See Also:

ImageWriteParam.setCompressionQuality(float), JPEG.DQT

getJPEGQuality

public static float getJPEGQuality(ImageInputStream input)
                            throws 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:

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

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

See Also:

ImageWriteParam.setCompressionQuality(float), JPEG.DQT

getQTables

public static JPEGQTable[] getQTables(List<JPEGSegment> segments)
                               throws IOException

Throws:

IOException

main

public static void main(String[] args)
                 throws IOException

Throws:

IOException