com.google.zxing.common
Class LocalBlockBinarizer

java.lang.Object
  com.google.zxing.Binarizer
      com.google.zxing.common.LocalBlockBinarizer

public final class LocalBlockBinarizer
extends Binarizer

This class implements a local thresholding algorithm, which while slower than the GlobalHistogramBinarizer, is fairly efficient for what it does. It is designed for high frequency images of barcodes with black data on white backgrounds. For this application, it does a much better job than a global blackpoint with severe shadows and gradients. However it tends to produce artifacts on lower frequency images and is therefore not a good general purpose binarizer for uses outside ZXing. NOTE: This class is still experimental and may not be ready for prime time yet.

Since:

BlackBerry API 6.0.0

Constructor Summary

LocalBlockBinarizer(LuminanceSource source)

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

Methods inherited from class com.google.zxing.Binarizer

getLuminanceSource

Methods inherited from class java.lang.Object

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

Constructor Detail

LocalBlockBinarizer

public LocalBlockBinarizer(LuminanceSource source)

Since:

BlackBerry API 6.0.0

Method Detail

getBlackRow

public BitArray getBlackRow(int y,
                            BitArray row)

Description copied from class: Binarizer

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.

Specified by:

getBlackRow in class Binarizer

Parameters:

y - The row to fetch, 0 <= y < 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).

Since:

BlackBerry API 6.0.0

getBlackMatrix

public BitMatrix getBlackMatrix()

Description copied from class: Binarizer

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.

Specified by:

getBlackMatrix in class Binarizer

Returns:

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

Since:

BlackBerry API 6.0.0

createBinarizer

public Binarizer createBinarizer(LuminanceSource source)

Description copied from class: Binarizer

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.

Specified by:

createBinarizer in class Binarizer

Parameters:

source - The LuminanceSource this Binarizer will operate on.

Returns:

A new concrete Binarizer implementation object.

Since:

BlackBerry API 6.0.0