coders
Class Encoder

java.lang.Object
  coders.Encoder

Direct Known Subclasses:

DifferenceExpansionEncoder, ProgressiveDivisibilityEncoder

public abstract class Encoder
extends java.lang.Object

Author:

Jonathan L Dautrich Jr.

Field Summary

protected boolean	encoded Indicates whether the encode operation has been executed.
protected Bitmap	encodedBitmap
private double	mse Mean Squared Error.
protected Bitmap	originalBitmap
protected BitSequence	payload
protected double	psnr
protected boolean	psnrComputed Indicates whether the PSNR (peak signal-to-noise ratio) has been computed for this encoding.

Constructor Summary

Encoder(Bitmap originalBitmap, BitSequence payload)
Initializes this encoder with the specified bitmap.

Method Summary

double	computePSNR() Computes and returns the PSNR (peak signal-to-noise ratio) for the current encoding.
protected abstract void	encode() Encodes the current bitmap.
Bitmap	getEncodedBitmap() Returns the encoded bitmap produced by this encoder, running the encode operation first if necessary.
Bitmap	getOriginalBitmap() Returns the original bitmap used as the basis for encoding.
BitSequence	getPayload() Retrieves the payload being encoded in the bitmap by this encoder.

Methods inherited from class java.lang.Object

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

Field Detail

originalBitmap

protected Bitmap originalBitmap

encodedBitmap

protected Bitmap encodedBitmap

payload

protected BitSequence payload

encoded

protected boolean encoded

Indicates whether the encode operation has been executed. If it has, the restored bitmap and the payload will be available for retrieval, and decode may not be executed again.

psnrComputed

protected boolean psnrComputed

Indicates whether the PSNR (peak signal-to-noise ratio) has been computed for this encoding. Encoding operation must occur before PSNR can be computed.

psnr

protected double psnr

mse

private double mse

Mean Squared Error. Used for computing PSNR.

Constructor Detail

Encoder

public Encoder(Bitmap originalBitmap,
               BitSequence payload)

Initializes this encoder with the specified bitmap. The originalBitmap should not be modified by the Encoder.

Parameters:

originalBitmap -

Method Detail

encode

protected abstract void encode()

Encodes the current bitmap. Should execute only if it has not already been called.

getOriginalBitmap

public Bitmap getOriginalBitmap()

Returns the original bitmap used as the basis for encoding.

Returns:

getEncodedBitmap

public Bitmap getEncodedBitmap()

Returns the encoded bitmap produced by this encoder, running the encode operation first if necessary.

Returns:

getPayload

public BitSequence getPayload()

Retrieves the payload being encoded in the bitmap by this encoder.

Returns:

the payload

computePSNR

public double computePSNR()

Computes and returns the PSNR (peak signal-to-noise ratio) for the current encoding. If the PSNR has already been computed, it will simply be returned. First invokes the encode operation if necessary. TODO: Currently only computes for the red (grayscale) pixel values.

Returns: