FITSMask.h

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// # FITSMask.h: A Lattice that can be used for temporary storage
// # Copyright (C) 1997,1998,1999,2000,2001,2002
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library is distributed in the hope that it will be useful, but WITHOUT
// # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef LATTICES_FITSMASK_H
#define LATTICES_FITSMASK_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/Array.h>
#include <casacore/lattices/Lattices/Lattice.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class TiledFileAccess;
 
// <summary>
// Provides an on-the-fly mask for FITS images
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="" tests="" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class="Lattice">Lattice</linkto>
//   <li> <linkto class="FITSImage">FITSImage</linkto>
// </prerequisite>
 
// <etymology>
// This class provides a pixel mask for the FITSImage class.
// </etymology>
 
// <synopsis>
// Masked values are indicated in FITS images via magic
// value blanking.  This class provides an on-the-fly mask.
// The doGetSlice function reads the data values and returns
// an Array<Bool> which is True (good) or False (bad - blanked)
//
// Because FITSMask inherits from Lattice<Bool> it can be
// used as the private pixel mask data member for FITSImage
// returned by the MaskedLattice::pixelMask() functions
//
// The FITSMask object is constructed from a TiledFileAccess
// object.  This must be the same one that the FITSImage
// object constructs internally.  It is shared by both
// FITSImage and FITSMask.
//
// </synopsis>
//
// <example>
// <srcblock>
// </srcblock>
// </example>
 
// <motivation>
// FITSImage provides native access to FITS image files
// and needede an efficient way to handle the pixel mask
// other than iterating all the way through the image
// first to set a mask.
// </motivation>
 
// # <todo asof="yyyy/mm/dd">
// #   <li> add this feature
// #   <li> fix this bug
// #   <li> start discussion of this possible extension
// # </todo>
 
class FITSMask : public Lattice<Bool> {
 public:
  // Constructor (for 32 bit floating point). The pointer is not cloned,
  // just copied.
  FITSMask(TiledFileAccess* tiledFileAccess);
 
  // Constructor (for 8 bit integers).  The pointer is not cloned, just copied
  // The scale, offset, magic blanking values must come from
  // the FITS header ('bscale', 'bzero', 'blank')
  FITSMask(TiledFileAccess* tiledFileAccess, Float scale, Float offset, uChar magic,
           Bool hasBlanks);
 
  // Constructor (for 16 bit integers).  The pointer is not cloned, just copied
  // The scale, offset, magic blanking values must come from
  // the FITS header ('bscale', 'bzero', 'blank')
  FITSMask(TiledFileAccess* tiledFileAccess, Float scale, Float offset, Short magic,
           Bool hasBlanks);
 
  // Constructor (for 32 bit integers).  The pointer is not cloned, just copied
  // The scale, offset, magic blanking values must come from
  // the FITS header ('bscale', 'bzero', 'blank')
  FITSMask(TiledFileAccess* tiledFileAccess, Float scale, Float offset, Int magic, Bool hasBlanks);
 
  // Copy constructor (reference semantics).  The TiledFileAccess pointer
  // is just copied.
  FITSMask(const FITSMask& other);
 
  // Destructor
  virtual ~FITSMask();
 
  // The assignment operator with reference semantics.
  // The TiledFileAccess pointer is just copied.
  FITSMask& operator=(const FITSMask& other);
 
  // Make a copy of the object (reference semantics).
  virtual Lattice<Bool>* clone() const;
 
  // Is the FITSMask writable? Returns False. Although it is not hard
  // to implement writing of the mask, data values would be lost
  // because of magic blanking.
  virtual Bool isWritable() const;
 
  // Return the shape of the Lattice including all degenerate
  // axes (ie. axes with a length of one)
  IPosition shape() const;
 
  // Do the actual getting of an array of values.
  virtual Bool doGetSlice(Array<Bool>& buffer, const Slicer& section);
 
  // Do the actual getting of an array of values.  Throws an exception.
  virtual void doPutSlice(const Array<Bool>& sourceBuffer, const IPosition& where,
                          const IPosition& stride);
 
  // Set the switch for also filtering 0.0 (besides NaNs).
  virtual void setFilterZero(Bool filterZero);
 
 private:
  // Mask out ONLY NaN's
  void filterNaN(Bool* pMask, const float* pData, uInt nelems);
 
  // Mask out NaN's and values 0.0
  void filterZeroNaN(Bool* pMask, const Float* pData, uInt nelems);
 
  //
  TiledFileAccess* itsTiledFilePtr;
  Array<Float> itsBuffer;
  Float itsScale, itsOffset;
  Short itsUCharMagic;
  Short itsShortMagic;
  Int itsLongMagic;
  Bool itsHasIntBlanks;
  Bool itsFilterZero;
};
 
}  // namespace casacore
 
#endif