com.google.zxing

Class Binarizer

java.lang.Object

com.google.zxing.Binarizer

Direct Known Subclasses:

GlobalHistogramBinarizer

public abstract class Binarizer
extends Object

This class hierarchy provides a set of methods to convert luminance data to 1 bit data. It allows the algorithm to vary polymorphically, for example allowing a very expensive thresholding technique for servers and a fast one for mobile. It also permits the implementation to vary, e.g. a JNI version for Android and a Java fallback version for other platforms.

Author:

dswitkin@google.com (Daniel Switkin)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Binarizer(LuminanceSource source)

Method Summary

Methods

Modifier and Type	Method and Description
abstract Binarizer	createBinarizer(LuminanceSource source) Creates a new object with the same type as this Binarizer implementation, but with pristine state.
abstract BitMatrix	getBlackMatrix() Converts a 2D array of luminance data to 1 bit data.
abstract BitArray	getBlackRow(int y, BitArray row) Converts one row of luminance data to 1 bit data.
int	getHeight()
LuminanceSource	getLuminanceSource()
int	getWidth()

Methods inherited from class java.lang.Object

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

Constructor Detail

Binarizer

protected Binarizer(LuminanceSource source)

Method Detail

getLuminanceSource

public final LuminanceSource getLuminanceSource()

getBlackRow

public abstract BitArray getBlackRow(int y,
                   BitArray row)
                              throws NotFoundException

Converts one row of luminance data to 1 bit data. May actually do the conversion, or return cached data. Callers should assume this method is expensive and call it as seldom as possible. This method is intended for decoding 1D barcodes and may choose to apply sharpening. For callers which only examine one row of pixels at a time, the same BitArray should be reused and passed in with each call for performance. However it is legal to keep more than one row at a time if needed.

Parameters:

y - The row to fetch, which must be in [0, bitmap height)

row - An optional preallocated array. If null or too small, it will be ignored. If used, the Binarizer will call BitArray.clear(). Always use the returned object.

Returns:

The array of bits for this row (true means black).

Throws:

NotFoundException - if row can't be binarized

getBlackMatrix

public abstract BitMatrix getBlackMatrix()
                                  throws NotFoundException

Converts a 2D array of luminance data to 1 bit data. As above, assume this method is expensive and do not call it repeatedly. This method is intended for decoding 2D barcodes and may or may not apply sharpening. Therefore, a row from this matrix may not be identical to one fetched using getBlackRow(), so don't mix and match between them.

Returns:

The 2D array of bits for the image (true means black).

Throws:

NotFoundException - if image can't be binarized to make a matrix

createBinarizer

public abstract Binarizer createBinarizer(LuminanceSource source)

Creates a new object with the same type as this Binarizer implementation, but with pristine state. This is needed because Binarizer implementations may be stateful, e.g. keeping a cache of 1 bit data. See Effective Java for why we can't use Java's clone() method.

Parameters:

source - The LuminanceSource this Binarizer will operate on.

Returns:

A new concrete Binarizer implementation object.

getWidth

public final int getWidth()

getHeight

public final int getHeight()