Package org.apache.tika.imageprocessing

Class BlankImageCheck

java.lang.Object

org.apache.tika.imageprocessing.BlankImageCheck

All Implemented Interfaces:

Serializable, ImageCheck

public class BlankImageCheck
extends Object
implements ImageCheck

Refuses a blank image: the share of pixels whose gray level differs from the image's most common gray level (the background) by more than tolerance is at most maxInk. Measured on a copy of at most 1,000 pixels a side. The default maxInk, 0.0001 (0.01 %), is below a page with a few lines of text: on 13,641 PDF pages it flagged the 87 with no ink at all and 3 with a single line. With despeckle (the default) a pixel counts as ink only if most of its 3 x 3 neighbourhood does, so scattered specks (a noisy scan) do not hide a blank page: salt-and-pepper noise of 0.1 % to 5 % comes out blank, and none of 600 text pages did. An image with transparency is blank only if it is blank over white and over black. An image it cannot read or decode is admitted.

Since:

Apache Tika 4.2

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.tika.parser.enricher.ImageCheck

ImageCheck.Verdict

Constructor Summary

Constructors

Constructor	Description
BlankImageCheck()

Method Summary

Modifier and Type	Method	Description
ImageCheck.Verdict	check(ImageProbe image, Metadata metadata, ParseContext context)
double	getMaxInk()
int	getTolerance()
boolean	isDespeckle()
void	setDespeckle(boolean despeckle)
void	setMaxInk(double maxInk)
void	setTolerance(int tolerance)

Methods inherited from class java.lang.Object

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

Constructor Details

BlankImageCheck

public BlankImageCheck()

Method Details

check

public ImageCheck.Verdict check(ImageProbe image,
 Metadata metadata,
 ParseContext context)
                         throws IOException

Specified by:

check in interface ImageCheck

Parameters:

image - the image and what earlier checks have already learned about it

metadata - the metadata of the image the engine would be handed

context - the parse context

Throws:

IOException

isDespeckle

public boolean isDespeckle()

setDespeckle

public void setDespeckle(boolean despeckle)

getMaxInk

public double getMaxInk()

setMaxInk

public void setMaxInk(double maxInk)

getTolerance

public int getTolerance()

setTolerance

public void setTolerance(int tolerance)