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java.lang.Objectucar.jpeg.jj2000.j2k.image.input.ImgReader
ucar.jpeg.jj2000.j2k.image.input.ImgReaderPPM
public class ImgReaderPPM
This class implements the ImgData interface for reading 8 bits unsigned data from a binary PPM file
After being read the coefficients are level shifted by subtracting 2^(nominal bit range - 1)
The transfer type (see ImgData) of this class is TYPE_INT.
This class is buffered: the 3 input components(R,G,B) are read when the first one (R) is asked. The 2 others are stored until they are needed.
NOTE: This class is not thread safe, for reasons of internal buffering.
jj2000.j2k.image.ImgData
Field Summary | |
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static int |
DC_OFFSET
DC offset value used when reading image |
Fields inherited from class ucar.jpeg.jj2000.j2k.image.input.ImgReader |
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h, nc, w |
Constructor Summary | |
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ImgReaderPPM(File file)
Creates a new PPM file reader from the specified file. |
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ImgReaderPPM(String fname)
Creates a new PPM file reader from the specified file name. |
Method Summary | |
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void |
close()
Closes the underlying file from where the image data is being read. |
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. |
String |
toString()
Returns a string of information about the object, more than 1 line long. |
Methods inherited from class ucar.jpeg.jj2000.j2k.image.input.ImgReader |
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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 |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
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public static int DC_OFFSET
Constructor Detail |
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public ImgReaderPPM(File file) throws IOException
file
- The input file.IOException
- If an error occurs while opening the file.
IOException
public ImgReaderPPM(String fname) throws IOException
fname
- The input file name.IOException
- If an error occurs while opening the file.
IOException
Method Detail |
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public 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 avergae 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.
This method implements buffering for the 3 components: When the first one is asked, all the 3 components are read and stored until they are needed.
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,
1 and 3 are valid.
getCompData(ucar.jpeg.jj2000.j2k.image.DataBlk, int)
,
JJ2KExceptionHandler
public final 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).
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
0,1 and 2 are valid.
getInternCompData(ucar.jpeg.jj2000.j2k.image.DataBlk, int)
,
JJ2KExceptionHandler
public boolean isOrigSigned(int c)
isOrigSigned
in class ImgReader
c
- The index of the component, from 0 to N-1.
public String toString()
toString
in class Object
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