jj2000.j2k.image.output
Class ImgWriterPGX

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

public class ImgWriterPGX

extends ImgWriter

This class extends the ImgWriter abstract class for writing PGX files. PGX is a custom monochrome file format invented specifically to simplify the use of VM3A with images of different bit-depths in the range 1 to 31 bits per pixel.

The file consists of a one line text header followed by the data.

Header: "PG"+ ws +<endianess>+ ws +[sign]+ws + <bit-depth>+" "+<width>+" "+<height>+'\n'

where:

• ws (white-spaces) is any combination of characters ' ' and '\t'.
• endianess equals "LM" or "ML"(resp. little-endian or big-endian)
• sign equals "+" or "-" (resp. unsigned or signed). If omited, values are supposed to be unsigned.
• bit-depth that can be any number between 1 and 31.
• width and height are the image dimensions (in pixels).

Data: The image binary values appear one after the other (in raster order) immediately after the last header character ('\n') and are byte-aligned (they are packed into 1,2 or 4 bytes per sample, depending upon the bit-depth value).

If the data is unsigned, level shifting is applied adding 2^(bit depth - 1)

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

See Also:

ImgWriter, BlkImgDataSrc

Field Summary

private int	bitDepth The bit-depth of the input file (must be between 1 and 31)
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
(package private) boolean	isSigned Whether the data must be signed when writing or not.
(package private) int	levShift Used with level-shiting
(package private) int	maxVal Used during saturation (2^bitdepth-1 if unsigned, 2^(bitdepth-1)-1 if signed)
(package private) int	minVal Used during saturation (0 if unsigned, -2^(bitdepth-1) if signed)
private int	offset The offset of the raw pixel data in the PGX file
private java.io.RandomAccessFile	out Where to write the data
private int	packBytes The pack length of one sample (in bytes, according to the output bit-depth

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

DEF_STRIP_HEIGHT, h, src, w

Constructor Summary

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

ImgWriterPGX(java.lang.String fname, BlkImgDataSrc imgSrc, int c, boolean isSigned)
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.

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

maxVal

int maxVal

Used during saturation (2^bitdepth-1 if unsigned, 2^(bitdepth-1)-1 if signed)

minVal

int minVal

Used during saturation (0 if unsigned, -2^(bitdepth-1) if signed)

levShift

int levShift

Used with level-shiting

isSigned

boolean isSigned

Whether the data must be signed when writing or not. In the latter case inverse level shifting must be applied

bitDepth

private int bitDepth

The bit-depth of the input file (must be between 1 and 31)

out

private java.io.RandomAccessFile out

Where to write the data

offset

private int offset

The offset of the raw pixel data in the PGX file

db

private DataBlkInt db

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

fb

private int fb

The number of fractional bits in the source data

c

private int c

The index of the component from where to get the data

packBytes

private int packBytes

The pack length of one sample (in bytes, according to the output bit-depth

buf

private byte[] buf

The line buffer.

Constructor Detail

ImgWriterPGX

public ImgWriterPGX(java.io.File out,
                    BlkImgDataSrc imgSrc,
                    int c,
                    boolean isSigned)
             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).

All the header informations are given by the BlkImgDataSrc source (component width, component height, bit-depth) and sign flag, which are provided to the constructor. The endianness is always big-endian (MSB first).

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.

isSigned - Whether the datas are signed or not (needed only when writing header).

See Also:

DataBlk

ImgWriterPGX

public ImgWriterPGX(java.lang.String fname,
                    BlkImgDataSrc imgSrc,
                    int c,
                    boolean isSigned)
             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).

All header information is given by the BlkImgDataSrc source (component width, component height, bit-depth) and sign flag, which are provided to the constructor. The endianness is always big-endian (MSB first).

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.

isSigned - Whether the datas are signed or not (needed only when writing header).

See Also:

DataBlk

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 and packed into 1,2 or 4 bytes (according to the bit-depth).

If the data is unisigned, level shifting is applied adding 2^(bit depth - 1)

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

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.