src/core/raster/qgscontrastenhancement.cpp

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/* **************************************************************************
                qgscontrastenhancement.cpp -  description
                       -------------------
begin                : Mon Oct 22 2007
copyright            : (C) 2007 by Peter J. Ersts
email                : ersts@amnh.org

This class contains code that was originally part of the larger QgsRasterLayer
class originally created circa 2004 by T.Sutton, Gary E.Sherman, Steve Halasz
****************************************************************************/

/* **************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "qgslogger.h"

#include "qgscontrastenhancement.h"
#include "qgscontrastenhancementfunction.h"
#include "qgslinearminmaxenhancement.h"
#include "qgslinearminmaxenhancementwithclip.h"
#include "qgscliptominmaxenhancement.h"

QgsContrastEnhancement::QgsContrastEnhancement( QgsRasterDataType theDataType )
{
  mLookupTable = 0;
  mContrastEnhancementFunction = 0;
  mEnhancementDirty = false;
  mContrastEnhancementAlgorithm = NoEnhancement;
  mRasterDataType = theDataType;

  mMinimumValue = minimumValuePossible( mRasterDataType );
  mMaximumValue = maximumValuePossible( mRasterDataType );
  mRasterDataTypeRange = mMaximumValue - mMinimumValue;

  mLookupTableOffset = mMinimumValue * -1;

  mContrastEnhancementFunction = new QgsContrastEnhancementFunction( mRasterDataType, mMinimumValue, mMaximumValue );

  //If the data type is larger than 16-bit do not generate a lookup table
  if ( mRasterDataTypeRange <= 65535.0 )
  {
    mLookupTable = new int[static_cast <int>( mRasterDataTypeRange+1 )];
  }

}

QgsContrastEnhancement::~QgsContrastEnhancement()
{
}
/*
 *
 * Static methods
 *
 */

double QgsContrastEnhancement::maximumValuePossible( QgsRasterDataType theDataType )
{
  switch ( theDataType )
  {
    case QGS_Byte:
      return std::numeric_limits<unsigned char>::max();
      break;
    case QGS_UInt16:
      return std::numeric_limits<unsigned short>::max();
      break;
    case QGS_Int16:
      return std::numeric_limits<short>::max();
      break;
    case QGS_UInt32:
      return std::numeric_limits<unsigned int>::max();
      break;
    case QGS_Int32:
      return std::numeric_limits<int>::max();
      break;
    case QGS_Float32:
      return std::numeric_limits<float>::max();
      break;
    case QGS_Float64:
      return std::numeric_limits<double>::max();
      break;
    case QGS_CInt16:
      return std::numeric_limits<short>::max();
      break;
    case QGS_CInt32:
      return std::numeric_limits<int>::max();
      break;
    case QGS_CFloat32:
      return std::numeric_limits<float>::max();
      break;
    case QGS_CFloat64:
      return std::numeric_limits<double>::max();
      break;
    case QGS_Unknown:
    case QGS_TypeCount:
      // XXX - mloskot: not handled?
      break;
  }

  return std::numeric_limits<double>::max();
}
double QgsContrastEnhancement::minimumValuePossible( QgsRasterDataType theDataType )
{
  switch ( theDataType )
  {
    case QGS_Byte:
      return std::numeric_limits<unsigned char>::min();
      break;
    case QGS_UInt16:
      return std::numeric_limits<unsigned short>::min();
      break;
    case QGS_Int16:
      return std::numeric_limits<short>::min();
      break;
    case QGS_UInt32:
      return std::numeric_limits<unsigned int>::min();
      break;
    case QGS_Int32:
      return std::numeric_limits<int>::min();
      break;
    case QGS_Float32:
      return std::numeric_limits<float>::max() * -1.0;
      break;
    case QGS_Float64:
      return std::numeric_limits<double>::max() * -1.0;
      break;
    case QGS_CInt16:
      return std::numeric_limits<short>::min();
      break;
    case QGS_CInt32:
      return std::numeric_limits<int>::min();
      break;
    case QGS_CFloat32:
      return std::numeric_limits<float>::max() * -1.0;
      break;
    case QGS_CFloat64:
      return std::numeric_limits<double>::max() * -1.0;
      break;
    case QGS_Unknown:
    case QGS_TypeCount:
      // XXX - mloskot: not handled?
      break;
  }

  return std::numeric_limits<double>::max() * -1.0;
}

/*
 *
 * Non-Static methods
 *
 */
int QgsContrastEnhancement::enhanceContrast( double theValue )
{
  if ( mEnhancementDirty )
  {
    generateLookupTable();
  }

  if ( mLookupTable && NoEnhancement != mContrastEnhancementAlgorithm )
  {
    return mLookupTable[static_cast <int>( theValue + mLookupTableOffset )];
  }
  else
  {
    // Even if the contrast enhancement algorithms is set to NoEnhancement
    // The input values will still have to be scaled for all data types
    // greater than 1 byte.
    return mContrastEnhancementFunction->enhance( theValue );
  }
}

bool QgsContrastEnhancement::generateLookupTable()
{
  mEnhancementDirty = false;

  if ( 0 == mContrastEnhancementFunction ) { return false; }
  if ( NoEnhancement == mContrastEnhancementAlgorithm ) { return false; }
  if ( QGS_Byte != mRasterDataType && QGS_UInt16 != mRasterDataType && QGS_Int16 != mRasterDataType ) { return false; }
  if ( !mLookupTable ) { return false; }

  QgsDebugMsg( "building lookup table" );
  QgsDebugMsg( "***MinimumValue : " + QString::number( mMinimumValue ) );
  QgsDebugMsg( "***MaximumValue : " + QString::number( mMaximumValue ) );
  QgsDebugMsg( "***mLookupTableOffset : " + QString::number( mLookupTableOffset ) );
  QgsDebugMsg( "***mRasterDataTypeRange : " + QString::number( mRasterDataTypeRange ) );

  for ( int myIterator = 0; myIterator <= mRasterDataTypeRange; myIterator++ )
  {
    mLookupTable[myIterator] = mContrastEnhancementFunction->enhance(( double )myIterator - mLookupTableOffset );
  }

  return true;
}

bool QgsContrastEnhancement::isValueInDisplayableRange( double theValue )
{

  if ( 0 != mContrastEnhancementFunction )
  {
    return mContrastEnhancementFunction->isValueInDisplayableRange( theValue );
  }

  return false;
}

void QgsContrastEnhancement::setContrastEnhancementAlgorithm( ContrastEnhancementAlgorithm theAlgorithm, bool generateTable )
{
  QgsDebugMsg( "called algorithm: " + QString::number(( int )theAlgorithm ) + " generate lookup table: " + QString::number(( int )generateTable ) );

  if ( theAlgorithm != mContrastEnhancementAlgorithm )
  {
    switch ( theAlgorithm )
    {
      case StretchToMinimumMaximum :
        mContrastEnhancementFunction = new QgsLinearMinMaxEnhancement( mRasterDataType, mMinimumValue, mMaximumValue );
        break;
      case StretchAndClipToMinimumMaximum :
        mContrastEnhancementFunction = new QgsLinearMinMaxEnhancementWithClip( mRasterDataType, mMinimumValue, mMaximumValue );
        break;
      case ClipToMinimumMaximum :
        mContrastEnhancementFunction = new QgsClipToMinMaxEnhancement( mRasterDataType, mMinimumValue, mMaximumValue );
        break;
      case UserDefinedEnhancement :
        //Do nothing
        break;
      default:
        mContrastEnhancementFunction = new QgsContrastEnhancementFunction( mRasterDataType, mMinimumValue, mMaximumValue );
        break;
    }

    mEnhancementDirty = true;
    mContrastEnhancementAlgorithm = theAlgorithm;

    if ( generateTable )
    {
      generateLookupTable();
    }
  }
}

void QgsContrastEnhancement::setContrastEnhancementFunction( QgsContrastEnhancementFunction* theFunction )
{
  QgsDebugMsg( "called" );

  if ( 0 != theFunction )
  {
    mContrastEnhancementFunction = theFunction;
    mContrastEnhancementAlgorithm = UserDefinedEnhancement;
    generateLookupTable();
  }
}

void QgsContrastEnhancement::setMaximumValue( double theValue, bool generateTable )
{
  QgsDebugMsg( "called value: " + QString::number( theValue ) + " generate lookup table: " + QString::number(( int )generateTable ) );

  if ( theValue > maximumValuePossible( mRasterDataType ) )
  {
    mMaximumValue = maximumValuePossible( mRasterDataType );
  }
  else
  {
    mMaximumValue = theValue;
  }

  if ( 0 != mContrastEnhancementFunction )
  {
    mContrastEnhancementFunction->setMaximumValue( theValue );
  }

  mEnhancementDirty = true;

  if ( generateTable )
  {
    generateLookupTable();
  }
}

void QgsContrastEnhancement::setMinimumValue( double theValue, bool generateTable )
{
  QgsDebugMsg( "called value: " + QString::number( theValue ) + " generate lookup table: " + QString::number(( int )generateTable ) );

  if ( theValue < minimumValuePossible( mRasterDataType ) )
  {
    mMinimumValue = minimumValuePossible( mRasterDataType );
  }
  else
  {
    mMinimumValue = theValue;
  }

  if ( 0 != mContrastEnhancementFunction )
  {
    mContrastEnhancementFunction->setMinimumValue( theValue );
  }

  mEnhancementDirty = true;

  if ( generateTable )
  {
    generateLookupTable();
  }
}