jj2000.j2k.image.output
Class ImgWriterPGM

java.lang.Object
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  +--jj2000.j2k.image.output.ImgWriter
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        +--jj2000.j2k.image.output.ImgWriterPGM

public class ImgWriterPGM

extends ImgWriter

This class writes a component from an image in 8 bit unsigned data to a binary PGM file. The size of the image that is written to the file is the size of the component from which to get the data, not the size of the source image (they differ if there is some sub-sampling).

Before writing, all coefficients are inversly level shifted and then "saturated" (they are limited to the nominal dynamic range).
Ex: if the nominal range is 0-255, the following algorithm is applied:
if coeff<0, output=0
if coeff>255, output=255
else output=coeff

The write() methods of an object of this class may not be called concurrently from different threads.

NOTE: This class is not thread safe, for reasons of internal buffering.

Field Summary

private byte[]	buf The line buffer.
private int	c The index of the component from where to get the data
private DataBlkInt	db A DataBlk, just used to avoid allocating a new one each time it is needed
private int	fb The number of fractional bits in the source data
private int	levShift Value used to inverse level shift
private int	offset The offset of the raw pixel data in the PGM file
private java.io.RandomAccessFile	out Where to write the data

Fields inherited from class jj2000.j2k.image.output.ImgWriter

DEF_STRIP_HEIGHT, h, src, w

Constructor Summary

ImgWriterPGM(java.io.File out, BlkImgDataSrc imgSrc, int c)
Creates a new writer to the specified File object, to write data from the specified component.

ImgWriterPGM(java.lang.String fname, BlkImgDataSrc imgSrc, int c)
Creates a new writer to the specified file, to write data from the specified component.

Method Summary

void	close() Closes the underlying file or netwrok connection to where the data is written.
void	flush() Writes all buffered data to the file or resource.
java.lang.String	toString() Returns a string of information about the object, more than 1 line long.
void	write() Writes the source's current tile to the output.
void	write(int ulx, int uly, int w, int h) Writes the data of the specified area to the file, coordinates are relative to the current tile of the source.
private void	writeHeaderInfo() Writes the header info of the PGM file : P5 width height 255

Methods inherited from class jj2000.j2k.image.output.ImgWriter

finalize, writeAll

Methods inherited from class java.lang.Object

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

Field Detail

levShift

private int levShift

Value used to inverse level shift

out

private java.io.RandomAccessFile out

Where to write the data

c

private int c

The index of the component from where to get the data

fb

private int fb

The number of fractional bits in the source data

db

private DataBlkInt db

A DataBlk, just used to avoid allocating a new one each time it is needed

offset

private int offset

The offset of the raw pixel data in the PGM file

buf

private byte[] buf

The line buffer.

Constructor Detail

ImgWriterPGM

public ImgWriterPGM(java.io.File out,
                    BlkImgDataSrc imgSrc,
                    int c)
             throws java.io.IOException

Creates a new writer to the specified File object, to write data from the specified component.

The size of the image that is written to the file is the size of the component from which to get the data, specified by b, not the size of the source image (they differ if there is some sub-sampling).

Parameters:

out - The file where to write the data

imgSrc - The source from where to get the image data to write.

c - The index of the component from where to get the data.

ImgWriterPGM

public ImgWriterPGM(java.lang.String fname,
                    BlkImgDataSrc imgSrc,
                    int c)
             throws java.io.IOException

Creates a new writer to the specified file, to write data from the specified component.

The size of the image that is written to the file is the size of the component from which to get the data, specified by b, not the size of the source image (they differ if there is some sub-sampling).

Parameters:

fname - The name of the file where to write the data

imgSrc - The source from where to get the image data to write.

c - The index of the component from where to get the data.

Method Detail

close

public void close()
           throws java.io.IOException

Closes the underlying file or netwrok connection to where the data is written. Any call to other methods of the class become illegal after a call to this one.

Specified by:

close in class ImgWriter

Throws:

java.io.IOException - If an I/O error occurs.

flush

public void flush()
           throws java.io.IOException

Writes all buffered data to the file or resource.

Specified by:

flush in class ImgWriter

Throws:

java.io.IOException - If an I/O error occurs.

write

public void write(int ulx,
                  int uly,
                  int w,
                  int h)
           throws java.io.IOException

Writes the data of the specified area to the file, coordinates are relative to the current tile of the source. Before writing, the coefficients are limited to the nominal range.

This method may not be called concurrently from different threads.

If the data returned from the BlkImgDataSrc source is progressive, then it is requested over and over until it is not progressive anymore.

Specified by:

write in class ImgWriter

Parameters:

ulx - The horizontal coordinate of the upper-left corner of the area to write, relative to the current tile.

uly - The vertical coordinate of the upper-left corner of the area to write, relative to the current tile.

Throws:

java.io.IOException - If an I/O error occurs.

write

public void write()
           throws java.io.IOException

Writes the source's current tile to the output. The requests of data issued to the source BlkImgDataSrc object are done by strips, in order to reduce memory usage.

If the data returned from the BlkImgDataSrc source is progressive, then it is requested over and over until it is not progressive anymore.

Specified by:

write in class ImgWriter

Throws:

java.io.IOException - If an I/O error occurs.

See Also:

DataBlk

writeHeaderInfo

private void writeHeaderInfo()
                      throws java.io.IOException

Writes the header info of the PGM file : P5 width height 255

Throws:

java.io.IOException - If there is an IOException

toString

public java.lang.String toString()

Returns a string of information about the object, more than 1 line long. The information string includes information from the underlying RandomAccessFile (its toString() method is called in turn).

Overrides:

toString in class java.lang.Object

Returns:

A string of information about the object.