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

JPEGQuality()

Method Summary

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