org.openimaj.image.text.extraction.swt

Class SWTTextDetector

java.lang.Object

org.openimaj.image.text.extraction.swt.SWTTextDetector

All Implemented Interfaces:

ImageAnalyser<FImage>

@Reference(type=Inproceedings,
           author={"Epshtein, B.","Ofek, E.","Wexler, Y."},
           title="Detecting text in natural scenes with stroke width transform",
           year="2010",
           booktitle="Computer Vision and Pattern Recognition (CVPR), 2010 IEEE Conference on",
           pages={"2963","2970"},
           customData={"keywords","image processing;text analysis;image operator;image pixel;natural images;natural scenes;stroke width transform;text detection;Colored noise;Computer vision;Engines;Filter bank;Geometry;Image segmentation;Layout;Optical character recognition software;Pixel;Robustness","doi","10.1109/CVPR.2010.5540041","ISSN","1063-6919"})
public class SWTTextDetector
extends Object
implements ImageAnalyser<FImage>

Implementation of the Stroke Width Transform text detection algorithm by Epshtein et al.

This is a (relatively) high-performance text detection technique that does not require training (except for parameter setting) and is language independent. The algorithm automatically identifies individual characters ("letters"), as well as performing word grouping and line segmentation.

There is an implicit assumption in this implementation that the text is *almost* horizontal. This implementation cannot be considered to be rotation invariant. It also has difficulties with curved text.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SWTTextDetector.Direction Text search "directions": Dark text on a lighter background, light text on a dark background and both.
static class	SWTTextDetector.Options Options for controlling the SWTTextDetector.

Field Summary

Fields

Modifier and Type	Field and Description
protected SWTTextDetector.Options	options The parameters of the algorithm

Constructor Summary

Constructors

Constructor and Description
SWTTextDetector() Construct the SWTTextDetector with the default parameters.
SWTTextDetector(SWTTextDetector.Options options) Construct the SWTTextDetector with the given parameters.

Method Summary

Modifier and Type	Method and Description
void	analyseImage(FImage image) Analyse an image.
protected void	analyseImage(FImage image, FImage swt)
List<LetterCandidate>	getLetters() Get the unfiltered detected characters.
List<LineCandidate>	getLines() Get the detected candidate lines of text
SWTTextDetector.Options	getOptions() Get the current options.

Methods inherited from class java.lang.Object

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

Field Detail

options

protected SWTTextDetector.Options options

The parameters of the algorithm

Constructor Detail

SWTTextDetector

public SWTTextDetector()

Construct the SWTTextDetector with the default parameters.

SWTTextDetector

public SWTTextDetector(SWTTextDetector.Options options)

Construct the SWTTextDetector with the given parameters.

Parameters:

options - the parameters

Method Detail

getOptions

public SWTTextDetector.Options getOptions()

Get the current options.

Returns:

the current options.

analyseImage

public void analyseImage(FImage image)

Description copied from interface: ImageAnalyser

Analyse an image.

Specified by:

analyseImage in interface ImageAnalyser<FImage>

Parameters:

image - The image to process in place.

analyseImage

protected void analyseImage(FImage image,
                            FImage swt)

getLines

public List<LineCandidate> getLines()

Get the detected candidate lines of text

Returns:

the lines of text

getLetters

public List<LetterCandidate> getLetters()

Get the unfiltered detected characters. Normally you would want to get the lines and then get the characters from each line as these will be filtered.

Returns:

the unfiltered characters

See Also:

getLines()