public class ImgReaderPGM extends ImgReader
After being read the coefficients are level shifted by subtracting 2^(nominal bit range-1)
The TransferType (see ImgData) of this class is TYPE_INT.
NOTE: This class is not thread safe, for reasons of internal buffering.
ImgData
Modifier and Type | Field and Description |
---|---|
private byte[] |
buf
The line buffer.
|
static int |
DC_OFFSET
DC offset value used when reading image
|
private RandomAccessFile |
in
Where to read the data from
|
private DataBlkInt |
intBlk
Temporary DataBlkInt object (needed when encoder uses floating-point
filters).
|
private int |
offset
The offset of the raw pixel data in the PGM file
|
private int |
rb
The number of bits that determine the nominal dynamic range
|
Constructor and Description |
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ImgReaderPGM(File file)
Creates a new PGM file reader from the specified file.
|
ImgReaderPGM(RandomAccessFile in)
Creates a new PGM file reader from the specified RandomAccessFile
object.
|
ImgReaderPGM(String fname)
Creates a new PGM file reader from the specified file name.
|
Modifier and Type | Method and Description |
---|---|
void |
close()
Closes the underlying RandomAccessFile from where the image data is
being read.
|
private void |
confirmFileType()
Checks that the RandomAccessIO begins with 'P5'
|
private byte |
countedByteRead()
Returns a byte read from the RandomAccessIO.
|
DataBlk |
getCompData(DataBlk blk,
int c)
Returns, in the blk argument, a block of image data containing the
specifed rectangular area, in the specified component.
|
int |
getFixedPoint(int c)
Returns the position of the fixed point in the specified component
(i.e.
|
DataBlk |
getInternCompData(DataBlk blk,
int c)
Returns, in the blk argument, the block of image data containing the
specifed rectangular area, in the specified component.
|
int |
getNomRangeBits(int c)
Returns the number of bits corresponding to the nominal range of the
data in the specified component.
|
boolean |
isOrigSigned(int c)
Returns true if the data read was originally signed in the specified
component, false if not.
|
private int |
readHeaderInt()
Returns an int read from the header of the PGM file.
|
private void |
skipCommentAndWhiteSpace()
Skips any line in the header starting with '#' and any space, tab, line
feed or carriage return.
|
String |
toString()
Returns a string of information about the object, more than 1 line
long.
|
getCompImgHeight, getCompImgWidth, getCompSubsX, getCompSubsY, getCompULX, getCompULY, getImgHeight, getImgULX, getImgULY, getImgWidth, getNomTileHeight, getNomTileWidth, getNumComps, getNumTiles, getNumTiles, getTile, getTileCompHeight, getTileCompWidth, getTileHeight, getTileIdx, getTilePartULX, getTilePartULY, getTileWidth, nextTile, setTile
public static int DC_OFFSET
private RandomAccessFile in
private int offset
private int rb
private byte[] buf
private DataBlkInt intBlk
public ImgReaderPGM(File file) throws IOException
file
- The input file.IOException
- If an error occurs while opening the file.public ImgReaderPGM(String fname) throws IOException
fname
- The input file name.IOException
- If an error occurs while opening the file.public ImgReaderPGM(RandomAccessFile in) throws EOFException, IOException
in
- From where to read the dataEOFException
- if an EOF is readIOException
- if an error occurs when opening the filepublic void close() throws IOException
close
in class ImgReader
IOException
- If an I/O error occurs.public int getNomRangeBits(int c)
If this number is b then the nominal range is between -2^(b-1) and 2^(b-1)-1, since unsigned data is level shifted to have a nominal average of 0.
c
- The index of the component.public int getFixedPoint(int c)
c
- The index of the component.public final DataBlk getInternCompData(DataBlk blk, int c)
After being read the coefficients are level shifted by subtracting 2^(nominal bit range - 1)
The rectangular area to return is specified by the 'ulx', 'uly', 'w' and 'h' members of the 'blk' argument, relative to the current tile. These members are not modified by this method. The 'offset' and 'scanw' of the returned data can be arbitrary. See the 'DataBlk' class.
If the data array in blk is null, then a new one is created if necessary. The implementation of this interface may choose to return the same array or a new one, depending on what is more efficient. Therefore, the data array in blk prior to the method call should not be considered to contain the returned data, a new array may have been created. Instead, get the array from blk after the method has returned.
The returned data always has its 'progressive' attribute unset (i.e. false).
When an I/O exception is encountered the JJ2KExceptionHandler is used. The exception is passed to its handleException method. The action that is taken depends on the action that has been registered in JJ2KExceptionHandler. See JJ2KExceptionHandler for details.
blk
- Its coordinates and dimensions specify the area to
return. Some fields in this object are modified to return the data.c
- The index of the component from which to get the data. Only 0
is valid.getCompData(jj2000.j2k.image.DataBlk, int)
,
JJ2KExceptionHandler
public DataBlk getCompData(DataBlk blk, int c)
After being read the coefficients are level shifted by subtracting 2^(nominal bit range - 1)
The rectangular area to return is specified by the 'ulx', 'uly', 'w' and 'h' members of the 'blk' argument, relative to the current tile. These members are not modified by this method. The 'offset' of the returned data is 0, and the 'scanw' is the same as the block's width. See the 'DataBlk' class.
If the data array in 'blk' is 'null', then a new one is created. If the data array is not 'null' then it is reused, and it must be large enough to contain the block's data. Otherwise an 'ArrayStoreException' or an 'IndexOutOfBoundsException' is thrown by the Java system.
The returned data has its 'progressive' attribute unset (i.e. false).
This method just calls 'getInternCompData(blk, n)'.
When an I/O exception is encountered the JJ2KExceptionHandler is used. The exception is passed to its handleException method. The action that is taken depends on the action that has been registered in JJ2KExceptionHandler. See JJ2KExceptionHandler for details.
blk
- Its coordinates and dimensions specify the area to
return. If it contains a non-null data array, then it must have the
correct dimensions. If it contains a null data array a new one is
created. The fields in this object are modified to return the data.c
- The index of the component from which to get the data. Only 0
is valid.getInternCompData(jj2000.j2k.image.DataBlk, int)
,
JJ2KExceptionHandler
private byte countedByteRead() throws IOException, EOFException
IOException
- If an I/O error occurs.EOFException
- If an EOF is readprivate void confirmFileType() throws IOException, EOFException
IOException
- If an I/O error occurs.EOFException
- If an EOF is readprivate void skipCommentAndWhiteSpace() throws IOException, EOFException
IOException
- If an I/O error occurs.EOFException
- if an EOF is readprivate int readHeaderInt() throws IOException, EOFException
IOException
- If an I/O error occurs.EOFException
- If an EOF is readpublic boolean isOrigSigned(int c)
isOrigSigned
in class ImgReader
c
- The index of the component, from 0 to N-1.public String toString()
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