/work/vvenc/source/Lib/EncoderLib/SEIFilmGrainAnalyzer.cpp

Source
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#include "SEIFilmGrainAnalyzer.h"

#include "CommonLib/MCTF.h"
#include "TrQuant_EMT.h"

using namespace vvenc;

// POLYFIT
static constexpr int      MAXORDER = 8;                                   // maximum order of polynomial fitting
static constexpr int      MAX_REAL_SCALE = 16;
static constexpr int      ORDER = 4;                                      // order of polynomial function
static constexpr int      QUANT_LEVELS = 4;                               // number of quantization levels in lloyd max quantization

static constexpr int      MIN_ELEMENT_NUMBER_PER_INTENSITY_INTERVAL = 8;
static constexpr int      MIN_POINTS_FOR_INTENSITY_ESTIMATION = 40;       // 5*8 = 40; 5 intervals with at least 8 points
static constexpr int      MIN_BLOCKS_FOR_CUTOFF_ESTIMATION = 2;           // 2 blocks of 64 x 64 size
static constexpr int      POINT_STEP = 16;                                // step size in point extension
static constexpr int      MAX_NUM_POINT_TO_EXTEND = 4;                    // max point in extension
static constexpr double   POINT_SCALE = 1.25;                             // scaling in point extension
static constexpr double   VAR_SCALE_DOWN = 1.2;                           // filter out large points
static constexpr double   VAR_SCALE_UP = 0.6;                             // filter out large points
static constexpr int      NUM_PASSES = 2;                                 // number of passes when fitting the function
static constexpr int      NBRS = 1;                                       // minimum number of surrounding points in order to keep it for further analysis (within the widnow range)
static constexpr int      WINDOW = 1;                                     // window to check surrounding points
static constexpr int      MIN_INTENSITY = 40;
static constexpr int      MAX_INTENSITY = 950;

static constexpr int      MAX_ALLOWED_MODEL_VALUES = 3;
static constexpr int      MAX_NUM_MODEL_VALUES = 6;                       // Maximum number of model values supported in FGC SEI

static constexpr int      BLK_8 = 8;
static constexpr int      BLK_16 = 16;
static constexpr int      BLK_32 = 32;
static constexpr int      BIT_DEPTH_8 = 8;


static constexpr int      MAX_BLOCKS = 40000;                             // higher than (3840*2160)/(16*16)

const int m_gx[CONV_HEIGHT_S][CONV_WIDTH_S]{ { -1, 0, 1 }, { -2, 0, 2 }, { -1, 0, 1 } };
const int m_gy[CONV_HEIGHT_S][CONV_WIDTH_S]{ { -1, -2, -1 }, { 0, 0, 0 }, { 1, 2, 1 } };

constexpr double FGAnalyzer::m_tapFilter[3];

void gradient_core ( PelStorage *buff1,
                     PelStorage *buff2,
                     PelStorage *tmpBuf1,
                     PelStorage *tmpBuf2,
                     uint32_t width,
                     uint32_t height,
                     uint32_t bitDepth,
                     ComponentID compID )
{
  // buff1 - magnitude; buff2 - orientation (Only luma in buff2)
  const uint32_t convWidthS = CONV_WIDTH_S;
  const uint32_t convHeightS = CONV_HEIGHT_S;
  const int maxClpRange = (1 << bitDepth) - 1;
  const int padding     = convWidthS / 2;

  buff1->get(compID).extendBorderPel( padding,
                                      padding );

  // Gx
  for (int i = 0; i < width; i++)
  {
    for (int j = 0; j < height; j++)
    {
      int acc = 0;
      int xOffset = i - convWidthS / 2;
      int yOffset = j - convHeightS / 2;
      for (int x = 0; x < convWidthS; x++)
      {
        for (int y = 0; y < convHeightS; y++)
        {
          acc += ( buff1->get(compID).at( x + xOffset, y + yOffset ) * m_gx[x][y] );
        }
      }
      tmpBuf1->Y().at(i, j) = acc;
    }
  }

  // Gy
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      int acc = 0;
      for ( int x = 0; x < convWidthS; x++ )
      {
        for ( int y = 0; y < convHeightS; y++ )
        {
          acc += (buff1->get(compID).at(x - convWidthS / 2 + i, y - convHeightS / 2 + j) * m_gy[x][y]);
        }
      }
      tmpBuf2->Y().at(i, j) = acc;
    }
  }

  // magnitude
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      Pel tmp                     = static_cast<Pel>((abs(tmpBuf1->Y().at(i, j)) + abs(tmpBuf2->Y().at(i, j))) / 2);
      buff1->get(compID).at(i, j) = static_cast<Pel>( Clip3((Pel) 0, (Pel) maxClpRange, tmp) );
    }
  }

  // Loop through each pixel
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      // Calculate edge direction angle
      Pel Dx = tmpBuf1->Y().at( i, j );
      Pel Dy = tmpBuf2->Y().at( i, j );
      float theta = 0.0;
      int quantized_direction = 0;

      if ( Dx == 0 )
      {
        if ( Dy == 0 )
          quantized_direction = 0;
        else
          quantized_direction = 90;
      }
      else
      {
        theta= ( atan( static_cast<double>( Dy )/(double)static_cast<double>( Dx ) ) ) ;
        if ( Dx < 0 )
        {
          if ( Dy >= 0 )
            theta += static_cast<float>( PI );
          else
            theta -= static_cast<float>( PI );
        }
        theta = std::fabs( theta );
        /* Convert actual edge direction to approximate value - quantize directions */
        if (( theta <= pi_8 ) || ( pi_7_8 < theta ))
        {
          quantized_direction = 0;
        }
        if (( pi_8 < theta ) && ( theta <= pi_3_8 ))
        {
          if ( Dy > 0 )
            quantized_direction = 45;
          else
            quantized_direction = 135;
        }
        if (( pi_3_8 < theta ) && ( theta <= pi_5_8 ))
        {
          quantized_direction = 90;
        }
        if (( pi_5_8 < theta ) && ( theta <= pi_7_8 ))
        {
          if ( Dy > 0 )
            quantized_direction = 135;
          else
            quantized_direction = 45;
        }
      }
      buff2->get(ComponentID(0)).at( i, j ) = quantized_direction;
    }
  }
  buff1->get(compID).extendBorderPel( padding, 
                                      padding );   // extend border for the next steps
}

// ====================================================================================================================
// Edge detection - Canny
// ====================================================================================================================

Canny::Canny()
{
  // init();
  gradient=gradient_core;
#if ENABLE_SIMD_OPT_FGA && defined( TARGET_SIMD_X86 )
  initFGACannyX86();
#endif
}

Canny::~Canny()
{
  // uninit();
}

void Canny::init ( uint32_t width,
                   uint32_t height,
                   ChromaFormat inputChroma )
{
  if (!m_orientationBuf)
  {
    m_orientationBuf = new PelStorage;
    m_orientationBuf->create( inputChroma,
                              Area(0, 0, width, height) );
  }

  if ( !m_gradientBufX )
  {
    m_gradientBufX = new PelStorage;
    m_gradientBufX->create ( inputChroma,
                             Area(0, 0, width, height) );
  }

  if ( !m_gradientBufY )
  {
    m_gradientBufY = new PelStorage;
    m_gradientBufY->create ( inputChroma,
                             Area(0, 0, width, height) );
  }
}

void Canny::destroy()
{
  if ( m_orientationBuf )
  {
    m_orientationBuf->destroy();
    delete m_orientationBuf;
    m_orientationBuf = nullptr;
  }

  if ( m_gradientBufX )
  {
    m_gradientBufX->destroy();
    delete m_gradientBufX;
    m_gradientBufX = nullptr;
  }

  if ( m_gradientBufY )
  {
    m_gradientBufY->destroy();
    delete m_gradientBufY;
    m_gradientBufY = nullptr;
  }
}

void Canny::suppressNonMax ( PelStorage *buff1,
                             PelStorage *buff2,
                             uint32_t width,
                             uint32_t height,
                             ComponentID compID )
{
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      int rowShift = 0, colShift = 0;
      switch ( buff2->get( ComponentID(0) ).at( i, j ) )
      {
      case 0:
        rowShift = 1;
        colShift = 0;
        break;
      case 45:
        rowShift = 1;
        colShift = 1;
        break;
      case 90:
        rowShift = 0;
        colShift = 1;
        break;
      case 135:
        rowShift = -1;
        colShift = 1;
        break;
      default: THROW("Unsupported gradient direction."); break;
      }

      Pel pelCurrent             = buff1->get(compID).at( i, j );
      Pel pelEdgeDirectionTop    = buff1->get(compID).at( i + rowShift, j + colShift );
      Pel pelEdgeDirectionBottom = buff1->get(compID).at( i - rowShift, j - colShift );
      if (( pelCurrent < pelEdgeDirectionTop ) || ( pelCurrent < pelEdgeDirectionBottom ))
      {
        buff2->get(ComponentID(0)).at( i, j ) = 0;   // supress
      }
      else
      {
        buff2->get(ComponentID(0)).at( i, j ) = buff1->get(compID).at( i, j );   // keep
      }
    }
  }
  buff1->get(compID).copyFrom( buff2->get( ComponentID(0) ) );
}

void Canny::doubleThreshold ( PelStorage *buff,
                              uint32_t width,
                              uint32_t height,
                              uint32_t bitDepth,
                              ComponentID compID )
{
  Pel strongPel = ( static_cast<Pel>( 1 ) << bitDepth) - 1;
  Pel weekPel   = ( static_cast<Pel>( 1 ) << (bitDepth - 1)) - 1;

  Pel highThreshold = 0;
  Pel lowThreshold  = strongPel;
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      highThreshold = std::max<Pel>( highThreshold,
                                     buff->get(compID).at( i, j ) );
    }
  }

  // global low and high threshold
  lowThreshold = static_cast<Pel>( m_lowThresholdRatio * highThreshold );
  highThreshold = Clip3( 0,
                         (1 << bitDepth) - 1,
                         m_highThresholdRatio * lowThreshold);   // Canny recommended a upper:lower ratio between 2:1 and 3:1.

  // strong, week, supressed
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      if ( buff->get(compID).at( i, j ) > highThreshold )
      {
        buff->get(compID).at( i, j ) = strongPel;
      }
      else if ( buff->get(compID).at( i, j ) <= highThreshold && buff->get(compID).at( i, j ) > lowThreshold )
      {
        buff->get(compID).at( i, j ) = weekPel;
      }
      else
      {
        buff->get(compID).at( i, j ) = 0;
      }
    }
  }

  buff->get(compID).extendBorderPel ( 1, 1 );   // extend one pixel on each side for the next step
}

void Canny::edgeTracking ( PelStorage *buff,
                           uint32_t width,
                           uint32_t height,
                           uint32_t windowWidth,
                           uint32_t windowHeight,
                           uint32_t bitDepth,
                           ComponentID compID )
{
  Pel strongPel = (static_cast<Pel>(1) << bitDepth) - 1;
  Pel weakPel   = (static_cast<Pel>(1) << (bitDepth - 1)) - 1;

  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      if ( buff->get(compID).at( i, j ) == weakPel )
      {
        bool strong = false;

        for ( int x = 0; x < windowWidth; x++ )
        {
          for ( int y = 0; y < windowHeight; y++ )
          {
            if ( buff->get(compID).at( x - windowWidth / 2 + i, y - windowHeight / 2 + j ) == strongPel )
            {
              strong = true;
              break;
            }
          }
        }

        if ( strong )
        {
          buff->get(compID).at( i, j ) = strongPel;
        }
        else
        {
          buff->get(compID).at( i, j ) = 0;   // supress
        }
      }
    }
  }
}

void Canny::detect_edges ( const PelStorage *orig,
                           PelStorage *dest,
                           uint32_t uiBitDepth,
                           ComponentID compID )
{
  /* No noise reduction - Gaussian blur is skipped;
   Gradient calculation;
   Non-maximum suppression;
   Double threshold;
   Edge Tracking by Hysteresis.*/

  uint32_t width      = orig->get( compID ).width,
           height     = orig->get( compID ).height;       // Width and Height of current frame
  uint32_t convWidthS  = CONV_WIDTH_S,
           convHeightS = CONV_HEIGHT_S;                 // Pixel's row and col positions for Sobel filtering
  uint32_t bitDepth    = uiBitDepth;

  dest->get(compID).copyFrom( orig->getBuf( compID ) );   // we skip blur in canny detector to catch as much as possible edges and textures

  /* Gradient calculation */
  gradient ( dest,
             m_orientationBuf,
             m_gradientBufX,
             m_gradientBufY,
             width,
             height,
             bitDepth,
             compID );

  /* Non - maximum suppression */
  suppressNonMax ( dest,
                   m_orientationBuf,
                   width,
                   height,
                   compID );

  /* Double threshold */
  doubleThreshold ( dest,
                    width,
                    height, 
                    bitDepth,
                    compID );

  /* Edge Tracking by Hysteresis */
  edgeTracking ( dest,
                 width,
                 height,
                 convWidthS,
                 convHeightS,
                 bitDepth,
                 compID ); 
}

// ====================================================================================================================
// Morphologigal operations - Dilation and Erosion
// ====================================================================================================================
int dilation_core ( PelStorage *buff,
                    PelStorage *Wbuf,
                    uint32_t bitDepth,
                    ComponentID compID,
                    int numIter,
                    int iter,
                    Pel Value )
{
  if ( iter == numIter )
  {
    return iter;
  }
  uint32_t width      = buff->get( compID ).width;
  uint32_t height     = buff->get( compID ).height;   // Width and Height of current frame
  uint32_t windowSize = KERNELSIZE;
  uint32_t padding    = windowSize / 2;

  Wbuf->bufs[0].copyFrom( buff->get( compID ) );

  buff->get(compID).extendBorderPel( padding,
                                     padding );

  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      bool strong = false;
      for ( int x = 0; x < windowSize; x++ )
      {
        for ( int y = 0; y < windowSize; y++ )
        {
          if ( buff->get( compID ).at( x - windowSize / 2 + i, y - windowSize / 2 + j ) == Value )
          {
            strong = true;
            break;
          }
        }
        if ( strong ) break;
      }
      if ( strong )
      {
        Wbuf->get(ComponentID(0)).at( i, j ) = Value;
      }
    }
  }

  buff->get(compID).copyFrom( Wbuf->bufs[0] );

  return dilation_core ( buff,
                         Wbuf,
                         bitDepth,
                         compID,
                         numIter,
                         ++iter,
                         Value );

}

Morph::Morph()
{
  // init();
  dilation=dilation_core;
#if ENABLE_SIMD_OPT_FGA && defined( TARGET_SIMD_X86 )
  initFGAMorphX86();
#endif
}

Morph::~Morph()
{
  // uninit();
}

void Morph::init ( uint32_t width,
                   uint32_t height )
{
  if ( !m_dilationBuf )
  {
    m_dilationBuf = new PelStorage;
    m_dilationBuf->create ( VVENC_CHROMA_400,
                            Area( 0, 0, width, height ) );
  }
  if ( !m_dilationBuf2 )
  {
    m_dilationBuf2 = new PelStorage;
    m_dilationBuf2->create ( VVENC_CHROMA_400,
                             Area( 0, 0, width >> 1, height >> 1 ) );
  }
  if ( !m_dilationBuf4 )
  {
    m_dilationBuf4 = new PelStorage;
    m_dilationBuf4->create( VVENC_CHROMA_400,
                              Area( 0, 0, width >> 2, height >> 2 ) );
  }
}

void Morph::destroy ()
{
  if ( m_dilationBuf )
  {
    m_dilationBuf->destroy();
    delete m_dilationBuf;
    m_dilationBuf = nullptr;
  }
  if ( m_dilationBuf2 )
  {
    m_dilationBuf2->destroy();
    delete m_dilationBuf2;
    m_dilationBuf2 = nullptr;
  }
  if ( m_dilationBuf4 )
  {
    m_dilationBuf4->destroy();
    delete m_dilationBuf4;
    m_dilationBuf4 = nullptr;
  }
}

int calcMeanCore ( const Pel* org,
                   const ptrdiff_t origStride,
                   const int w,
                   const int h )
{
  // calculate average
  int avg = 0;
  for( int y1 = 0; y1 < h; y1++ )
  {
    for( int x1 = 0; x1 < w; x1++ )
    {
      avg = avg + *( org + x1 + y1 * origStride );
    }
  }
  return avg;
}

// ====================================================================================================================
// Film Grain Analysis Functions
// ====================================================================================================================
FGAnalyzer::FGAnalyzer( bool enableOpt )
{
  calcVar     = calcVarCore;
  calcMean    = calcMeanCore;
  fastDCT2_64 = fastForwardDCT2_B64;

  if( enableOpt )
  {
#if ENABLE_SIMD_OPT_FGA && defined( TARGET_SIMD_X86 )
    initFGAnalyzerX86();
#endif
#if ENABLE_SIMD_OPT_FGA && defined( TARGET_SIMD_ARM )
    initFGAnalyzerARM();
#endif
  }
}

FGAnalyzer::~FGAnalyzer()
{
}

// initialize film grain parameters
void FGAnalyzer::init ( const int width,
                        const int height,
                        const ChromaFormat inputChroma,
                        const int *outputBitDepths,
                        const bool doAnalysis[] )
{
  m_log2ScaleFactor = 2;
  for (int i = 0; i < ComponentID::MAX_NUM_COMP; i++)
  {
    m_compModel[i].presentFlag           = true;
    m_compModel[i].numModelValues        = 3;
    m_compModel[i].numIntensityIntervals = 1;
    m_compModel[i].intensityValues.resize(VVENC_MAX_NUM_INTENSITIES);
    for ( int j = 0; j < VVENC_MAX_NUM_INTENSITIES; j++ )
    {
      m_compModel[i].intensityValues[j].intensityIntervalLowerBound = 10;
      m_compModel[i].intensityValues[j].intensityIntervalUpperBound = 250;
      m_compModel[i].intensityValues[j].compModelValue.resize( MAX_ALLOWED_MODEL_VALUES );
      for ( int k = 0; k < m_compModel[i].numModelValues; k++ )
      {
        // half intensity for chroma. Provided value is default value, manually tuned.
        m_compModel[i].intensityValues[j].compModelValue[k] = i == 0 ? 26 : 13;
      }
    }
    m_doAnalysis[i] = doAnalysis[i];
  }

  // initialize picture parameters and create buffers
  m_bitDepths                   = const_cast<int*>( outputBitDepths );
  m_inputChromaFormat           = inputChroma;
  // Allocate memory for m_coeffBuf and m_dctGrainBlockList
  m_coeffBuf = (TCoeff*)xMalloc( TCoeff, width * height );
  int N = (width * height) / (DATA_BASE_SIZE * DATA_BASE_SIZE);
  m_dctGrainBlockList = new CoeffBuf[N];

  std::fill( std::begin(vecMean), std::end(vecMean), 0 );
  std::fill( std::begin(vecVar), std::end(vecVar), 0 );

  // Connect portions of m_coeffBuf memory with m_dctGrainBlockList
  for ( int i = 0; i < N; ++i )
  {
    m_dctGrainBlockList[i].buf = m_coeffBuf + i * ( DATA_BASE_SIZE * DATA_BASE_SIZE );
    m_dctGrainBlockList[i].stride = DATA_BASE_SIZE;
    m_dctGrainBlockList[i].height = m_dctGrainBlockList[i].width = DATA_BASE_SIZE;
  }

  m_edgeDetector.init ( width,
                        height,
                        inputChroma );

  m_morphOperation.init ( width,
                          height );

  int margin = m_edgeDetector.m_convWidthG / 2;   // set margin for padding for filtering
  int      newWidth2 = width / 2;
  int      newHeight2 = height / 2;
  int      newWidth4 = width / 4;
  int      newHeight4 = height / 4;

  if ( !m_maskBuf )
  {
    m_maskBuf = new PelStorage;
    m_maskBuf->create ( inputChroma,
                        Area(0, 0, width, height),
                        0, margin,
                        0, false );
  }

  if ( !m_grainEstimateBuf )
  {
     m_grainEstimateBuf = new PelStorage;
     m_grainEstimateBuf->create( inputChroma,
                                Area(0, 0, width, height),
                                0, 0,
                                0, false );
  }

  if ( !m_workingBufSubsampled2 )
  {
    m_workingBufSubsampled2 = new PelStorage;
    m_workingBufSubsampled2->create( inputChroma,
                                     Area(0, 0, newWidth2, newHeight2),
                                     0, margin,
                                     0, false );
  }

  if ( !m_maskSubsampled2 )
  {
    m_maskSubsampled2 = new PelStorage;
    m_maskSubsampled2->create( inputChroma,
                               Area(0, 0, newWidth2, newHeight2),
                               0, margin,
                               0, false );
  }
  if ( !m_workingBufSubsampled4 )
  {
    m_workingBufSubsampled4 = new PelStorage;
    m_workingBufSubsampled4->create( inputChroma,
                                     Area(0, 0, newWidth4, newHeight4),
                                     0, margin,
                                     0, false );
  }

  if ( !m_maskSubsampled4 )
  {
    m_maskSubsampled4 = new PelStorage;
    m_maskSubsampled4->create( inputChroma,
                               Area(0, 0, newWidth4, newHeight4),
                               0, margin,
                               0, false );
  }
  if ( !m_maskUpsampled )
  {
    m_maskUpsampled = new PelStorage;
    m_maskUpsampled->create( inputChroma,
                             Area(0, 0, width, height),
                             0, margin,
                             0, false );
  }
  if ( !m_DCTinout )
  {
    m_DCTinout = ( TCoeff* ) xMalloc( TCoeff, DATA_BASE_SIZE * DATA_BASE_SIZE );
  }
  if ( !m_DCTtemp )
  {
    m_DCTtemp = ( TCoeff* ) xMalloc( TCoeff, DATA_BASE_SIZE * DATA_BASE_SIZE );
  }

}

// delete picture buffers
void FGAnalyzer::destroy()
{
  if ( m_maskBuf != nullptr )
  {
    m_maskBuf->destroy();
    delete m_maskBuf;
    m_maskBuf = nullptr;
  }

  if ( m_grainEstimateBuf )
  {
    m_grainEstimateBuf->destroy();
    delete m_grainEstimateBuf;
    m_grainEstimateBuf = nullptr;
  }

  if ( m_workingBufSubsampled2 )
  {
    m_workingBufSubsampled2->destroy();
    delete m_workingBufSubsampled2;
    m_workingBufSubsampled2 = nullptr;
  }
  if ( m_maskSubsampled2 )
  {
    m_maskSubsampled2->destroy();
    delete m_maskSubsampled2;
    m_maskSubsampled2 = nullptr;
  }
  
  if ( m_workingBufSubsampled4 )
  {
    m_workingBufSubsampled4->destroy();
    delete m_workingBufSubsampled4;
    m_workingBufSubsampled4 = nullptr;
  }
  if ( m_maskSubsampled4 )
  {
    m_maskSubsampled4->destroy();
    delete m_maskSubsampled4;
    m_maskSubsampled4 = nullptr;
  }
  if ( m_maskUpsampled )
  {
    m_maskUpsampled->destroy();
    delete m_maskUpsampled;
    m_maskUpsampled = nullptr;
  }
  if ( m_DCTinout )
  {
    xFree( m_DCTinout );
    m_DCTinout = nullptr;
  }
  if ( m_DCTtemp )
  {
    xFree( m_DCTtemp );
    m_DCTtemp = nullptr;
  }

  xFree ( m_coeffBuf );

  if ( m_dctGrainBlockList )
  {
    delete[] m_dctGrainBlockList;
    m_dctGrainBlockList = nullptr;
  }

  // Clear vectors to release memory
  finalIntervalsandScalingFactors.clear();
  vec_mean_intensity.clear();
  vec_variance_intensity.clear();
  element_number_per_interval.clear();
  vecMean.clear();
  vecVar.clear();
  tmp_data_x.clear();
  tmp_data_y.clear();
  scalingVec.clear();
  quantVec.clear();
  coeffs.clear();

  m_edgeDetector.destroy ();
  m_morphOperation.destroy ();
}

// find flat and low complexity regions of the frame
void FGAnalyzer::findMask( ComponentID compId )
{
  const unsigned padding    = m_edgeDetector.m_convWidthG / 2;   // for filtering
  int bitDepth  = m_bitDepths[toChannelType( compId )];

  // Step 1: Subsample the original picture to two lower resolutions.
  subsample ( *m_workingBufSubsampled2,
              2,
              padding,
              compId );
  subsample ( *m_workingBufSubsampled4,
              4,
              padding,
              compId );

  /* Step 2: Full Resolution processing:
   * For each component(luma and chroma), detect edges and suppress low intensity regions.
   * Apply dilation to each component.*/
  m_edgeDetector.detect_edges ( m_workingBuf,
                                m_maskBuf,
                                bitDepth,
                                compId );
  suppressLowIntensity ( *m_workingBuf,
                         *m_maskBuf,
                         bitDepth,
                         compId );
  
  Pel strongPel = ( static_cast<Pel>( 1 ) << bitDepth ) - 1;
  m_morphOperation.dilation ( m_maskBuf,
                              m_morphOperation.m_dilationBuf,
                              bitDepth,
                              compId,
                              4,
                              0,
                              strongPel );
  
  
  /* Step 3: Subsampled 2 processing:
   * Detect edges and suppresses low intensity regions for each component.
   * Apply dilation to each component.
   * Upsample the result and combine it with the full-resolution mask.*/
  m_edgeDetector.detect_edges ( m_workingBufSubsampled2,
                                m_maskSubsampled2,
                                bitDepth,
                                compId );
  suppressLowIntensity ( *m_workingBufSubsampled2,
                         *m_maskSubsampled2,
                         bitDepth,
                         compId );
  
    
  m_morphOperation.dilation ( m_maskSubsampled2,
                              m_morphOperation.m_dilationBuf2,
                              bitDepth,
                              compId,
                              3,
                              0,
                              strongPel );


  // upsample, combine maskBuf and maskUpsampled
  upsample ( *m_maskSubsampled2,
             2,
             compId );
  combineMasks ( compId );

  /* Step 4: Subsampled 4 processing:
   * Detect edges and suppresses low intensity regions for each component.
   * Apply dilation to each component.
   * Upsample the result and combine it with the full-resolution mask.*/
  m_edgeDetector.detect_edges ( m_workingBufSubsampled4,
                                m_maskSubsampled4,
                                bitDepth,
                                compId );
  suppressLowIntensity ( *m_workingBufSubsampled4,
                         *m_maskSubsampled4,
                         bitDepth,
                         compId );

  m_morphOperation.dilation ( m_maskSubsampled4,
                              m_morphOperation.m_dilationBuf4,
                              bitDepth,
                              compId,
                              2,
                              0,
                              strongPel );

  // upsample, combine maskBuf and maskUpsampled
  upsample ( *m_maskSubsampled4,
             4,
             compId );
  combineMasks ( compId );

  /* Step 5: Final dilation and erosion
   * Apply final dilation to fill the holes and erosion for each component. */
  m_morphOperation.dilation ( m_maskBuf,
                              m_morphOperation.m_dilationBuf,
                              bitDepth,
                              compId,
                              2,
                              0,
                              strongPel );
  // erosion -> dilation with value 0
  m_morphOperation.dilation ( m_maskBuf,
                              m_morphOperation.m_dilationBuf,
                              bitDepth,
                              compId,
                              1,
                              0,
                              0 );
}

void FGAnalyzer::suppressLowIntensity ( const PelStorage &buff1,
                                        PelStorage &buff2,
                                        uint32_t bitDepth, 
                                        ComponentID compId )
{
  // buff1 - intensity values ( luma or chroma samples); buff2 - mask

  int width                 = buff2.get( compId ).width;
  int height                = buff2.get( compId ).height;
  Pel maxIntensity          = static_cast <Pel>( 1 << bitDepth ) - 1;
  Pel lowIntensityThreshold = static_cast<Pel>( m_lowIntensityRatio * maxIntensity );

  // strong, weak, supressed
  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      // Check if the intensity is below the threshold
      if ( buff1.get( compId ).at( i, j ) < lowIntensityThreshold )
      {
        // Set the corresponding mask value to maxIntensity
        buff2.get( compId ).at( i, j ) = maxIntensity;
      }
    }
  }
}

void FGAnalyzer::subsample ( PelStorage &output,
                             const int factor,
                             const int padding,
                             ComponentID compId ) const
{
  const int newWidth  = m_workingBuf->get( compId ).width / factor;
  const int newHeight = m_workingBuf->get( compId ).height / factor;

  const Pel *srcRow    = m_workingBuf->get( compId ).buf;
  const ptrdiff_t srcStride = m_workingBuf->get( compId ).stride;
  Pel *dstRow    = output.get( compId ).buf;   // output is tmp buffer with only one component for binary mask
  const ptrdiff_t dstStride = output.get( compId ).stride;

  for ( int y = 0; y < newHeight; y++, srcRow += factor * srcStride, dstRow += dstStride )
  {
    const Pel *inRow      = srcRow;
    const Pel *inRowBelow = srcRow + srcStride;
    Pel *      target     = dstRow;

    for ( int x = 0; x < newWidth; x++ )
    {
      target[x] = ( inRow[0] + inRowBelow[0] + inRow[1] + inRowBelow[1] + 2 ) >> 2;
      inRow += factor;
      inRowBelow += factor;
    }
  }

  if ( padding )
  {
    // Extend border with padding
    output.get( compId ).extendBorderPel ( padding,
                                           padding );
  }
}

void FGAnalyzer::upsample ( const PelStorage &input,
                            const int factor,
                            const int padding,
                            ComponentID compId ) const
{
  // binary mask upsampling
  // use simple replication of pixels

  const int width  = input.get(compId).width;
  const int height = input.get(compId).height;

  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      Pel currentPel = input.get( compId ).at( i, j );

      for ( int x = 0; x < factor; x++ )
      {
        for ( int y = 0; y < factor; y++ )
        {
          m_maskUpsampled->get( compId ).at( i * factor + x, j * factor + y ) = currentPel;
        }
      }
    }
  }

  if ( padding )
  {
    m_maskUpsampled->get( compId ).extendBorderPel( padding,
                                                    padding );
  }
}

void FGAnalyzer::combineMasks( ComponentID compId )
{
  const int width = m_maskBuf->get( compId ).width;
  const int height = m_maskBuf->get( compId ).height;

  for ( int i = 0; i < width; i++ )
  {
    for ( int j = 0; j < height; j++ )
    {
      m_maskBuf->get( compId ).at( i, j ) = ( m_maskBuf->get( compId ).at( i, j ) | m_maskUpsampled->get( compId ).at( i, j ) );
    }
  }
}

// estimate cut-off frequencies and scaling factors for different intensity intervals
void FGAnalyzer::estimateGrainParameters ( Picture *pic )
{
  m_originalBuf = &pic->getOrigBuffer();                                   // original frame
  m_workingBuf = &pic->getFilteredOrigBuffer();                            // mctf filtered frame

  // Determine blockSize dynamically based on the frame resolution
  int blockSize = BLK_8;
  uint32_t picSizeInLumaSamples = m_workingBuf->Y().height * m_workingBuf->Y().width;
  if ( picSizeInLumaSamples >= 7680 * 4320 )
  {
    // 8K resolution
    blockSize = BLK_32;
  }
  else if ( picSizeInLumaSamples >= 3840 * 2160 )
  {
    // 4K resolution
    blockSize = BLK_16;
  }
  else
  {
    blockSize = BLK_8;
  }

  findMask( COMP_Y );                                                       // Generate mask for luma only

  // find difference between original and filtered/reconstructed frame => film grain estimate
  m_grainEstimateBuf->subtract( pic->getOrigBuffer(),
                                pic->getFilteredOrigBuffer() );

  for ( int compIdx = 0; compIdx < getNumberValidComponents( m_inputChromaFormat ); compIdx++ )
  {
    ComponentID  compID          = ComponentID( compIdx );
    uint32_t     width           = m_workingBuf->getBuf( compID ).width;    // Width of current frame
    uint32_t     height          = m_workingBuf->getBuf( compID ).height;   // Height of current frame
    uint32_t     windowSize      = DATA_BASE_SIZE;                          // Size for Film Grain block
    int          bitDepth        = m_bitDepths[toChannelType( compID )];
    int          detect_edges    = 0;
    int          mean            = 0;
    int          var             = 0;
    m_numDctGrainBlocks          = 0;

    // Clear vectors before computing for each component
    vecMean.clear();
    vecVar.clear();
    tmp_data_x.clear();
    tmp_data_y.clear();
    scalingVec.clear();
    quantVec.clear();
    coeffs.clear();

    for ( int i = 0; i <= width - windowSize; i += windowSize )
    { // loop over windowSize x windowSize blocks
      for ( int j = 0; j <= height - windowSize; j += windowSize )
      {
        if ( compID == COMP_Y )
        {
          detect_edges = countEdges ( windowSize,
                                      i,
                                      j,
                                      compID );  // for flat region without edges
        }
        else
        {
          detect_edges = 1;                      // always process for chroma
        }
        if ( detect_edges )   // selection of uniform, flat and low-complexity area; extend to other features, e.g., variance.
        { // find transformed blocks; cut-off frequency estimation is done on 64 x 64 blocks as low-pass filtering on synthesis side is done on 64 x 64 blocks.
          CoeffBuf& currentCoeffBuf = m_dctGrainBlockList[m_numDctGrainBlocks++];
          blockTransform ( currentCoeffBuf,
                           i,
                           j,
                           bitDepth,
                           compID );
        }

        int step = windowSize / blockSize;
        for ( int k = 0; k < step; k++ )
        {
          for ( int m = 0; m < step; m++ )
          {
            if ( compID == COMP_Y )
            {
              detect_edges = countEdges ( blockSize,
                                          i + k * blockSize,
                                          j + m * blockSize,
                                          compID );   // for flat region without edges
            }
            else
            {
              detect_edges = 1;  // always process for chroma
            }
            if ( detect_edges )   // selection of uniform, flat and low-complexity area; extend to other features, e.g., variance.
            {
              // collect all data for parameter estimation; mean and variance are caluclated on blockSize x blockSize blocks
              uint32_t stride = m_grainEstimateBuf->get( compID ).stride;
              double varD = calcVar ( m_grainEstimateBuf->get( compID ).buf + ( ( j + m * blockSize ) * stride ) + i + ( k * blockSize ),
                                      stride,
                                      blockSize,
                                      blockSize );
              varD = varD / (( blockSize * blockSize ));
              var = static_cast<int>( varD + 0.5 );
              stride = m_workingBuf->get( compID ).stride;
              mean = calcMean ( m_workingBuf->get( compID ).buf + ( ( j + m * blockSize ) * stride ) + i + ( k * blockSize ),
                                stride,
                                blockSize,
                                blockSize );
              mean = static_cast<int>(static_cast<double>( mean ) / ( blockSize * blockSize ) + 0.5 );

              // regularize high variations; controls excessively fluctuating points
              double tmp = 2.75 * pow( static_cast<double>( var ), 0.5 ) + 0.5;
              var = static_cast<int>( tmp ); 
              // limit data points to meaningful values. higher variance can be result of not perfect mask estimation (non-flat regions fall in estimation process)
              if ( var < ( MAX_REAL_SCALE << ( bitDepth - BIT_DEPTH_8 ) ) )
              {
                vecMean.push_back( mean );    // mean of the filtered frame
                vecVar.push_back( var );      // variance of the film grain estimate
              }
            }
          }
        }
      }
    }

    // calculate film grain parameters
    estimateCutoffFreqAdaptive( compID );
    estimateScalingFactors ( bitDepth,
                             compID );

    // Clear vectors after estimation
    vecMean.clear();
    vecVar.clear();
    finalIntervalsandScalingFactors.clear();
  }
}

/* This function calculates the scaling factors for film grain by analyzing the variance of intensity intervals.
 * The primary steps include fitting a polynomial regression function to the intensity - variance data points,
 * smoothing the resulting scaling function, and performing Lloyd - Max quantization to derive the final scaling factors.
 * The estimated parameters are then set for each intensity interval.*/
void FGAnalyzer::estimateScalingFactors ( uint32_t bitDepth,
                                          ComponentID compId )
{
  // if cutoff frequencies are not estimated previously, do not proceed since presentFlag is set to false in a previous step
  if ( !m_compModel[compId].presentFlag || vecMean.size() < MIN_POINTS_FOR_INTENSITY_ESTIMATION )
  {
    return;   // If there is no enough points to estimate film grain intensities, default or previously estimated
              // parameters are used
  }

  double              distortion = 0.0;

  // Fit the points with the curve and perform Lloyd Max quantization.
  bool valid;
  for ( int i = 0; i < NUM_PASSES; i++ )   // if num_passes = 2, filtering of the dataset points is performed
  {
    valid = fitFunction ( ORDER,
                          bitDepth,
                          i );   // n-th order polynomial regression for scaling function estimation
    if ( !valid )
    {
      coeffs.clear();
      scalingVec.clear();
      quantVec.clear();
      break;
    }
  }

  if ( valid )
  {
    avgScalingVec ( bitDepth );   // scale with previously fitted function to smooth the intensity
    valid = lloydMax ( distortion,
                       bitDepth );   // train quantizer and quantize curve using Lloyd Max
  }

  // Based on quantized intervals, set intensity region and scaling parameter
  if ( valid )   // if not valid, reuse previous parameters (for example, if var is all zero)
  {
    setEstimatedParameters ( bitDepth,
                             compId );
  }

  coeffs.clear();
  scalingVec.clear();
  quantVec.clear();

}

/*This function divides the specified range(rows or columns) of the `meanSquaredDctGrain` matrix into bins
* and calculates the average value of each bin.If the average value of a bin exceeds the given threshold,
* the bin is considered significant and its starting index is recorded in the `significantIndices` vector.
* The function can be used to adaptively refine the search for significant values in the matrix by focusing
* on specific rows or columns iteratively.*/
void FGAnalyzer::adaptiveSampling ( int bins,
                                    double threshold,
                                    std::vector<int>& significantIndices,
                                    bool isRow,
                                    int startIdx )
{
  int binSize = DATA_BASE_SIZE / bins;
  for ( int i = 0; i < bins; i++ )
  {
    double sum = 0;
    for ( int j = 0; j < binSize; j++ )
    {
      int idx = startIdx + i * binSize + j;
      if ( idx >= DATA_BASE_SIZE )
          break;  // Ensure we don't go out of bounds
      sum += isRow ? meanSquaredDctGrain[idx][0] : meanSquaredDctGrain[0][idx];
    }
    sum /= binSize;
    if ( sum > threshold )
    {
      significantIndices.push_back( startIdx + i * binSize );
    }
  }
}


/*This function refines the cutoff frequency estimation by adaptively sampling the mean squared DCT grain values
 * matrix. Instead of analyzing every row and column, it focuses on significant bins determined by the adaptive sampling
 * method. The horizontal and vertical cutoff frequencies are estimated by examining the mean values of these significant
 * bins, making the process more efficient and reducing computational overhead.
 * The function performs the following steps :
 * 1. Initializes mean squared DCT grain matrix and mean vectors for rows and columns.
 * 2. Iterates through the DCT grain blocks to calculate the average block for each coefficient.
 * 3. Uses the adaptive sampling method to identify significant rows and columns.
 * 4. Estimates the cutoff frequencies based on the mean values of the significant rows and columns.
 * 5. Updates the component model with the estimated cutoff frequencies.*/
void FGAnalyzer::estimateCutoffFreqAdaptive( ComponentID compId )
{
  const int coarseBins = 8; // Initial coarse sampling bins
  const int refineBins = 4; // Bins for each refinement step
  const int maxIterations = 3; // Maximum refinement iterations
  const double threshold = 0.1; // Threshold to identify significant bins

  std::memset( meanSquaredDctGrain, 0, sizeof( meanSquaredDctGrain ) );

  // Calculate mean squared DCT grain values
  for ( int x = 0; x < DATA_BASE_SIZE; x++ )
  {
    for ( int y = 0; y < DATA_BASE_SIZE; y++ )
    {
      for ( int i = 0; i < m_numDctGrainBlocks; i++ )
      {
        meanSquaredDctGrain[x][y] += m_dctGrainBlockList[i].at( x, y );
      }
      meanSquaredDctGrain[x][y] /= m_numDctGrainBlocks;
    }
  }

  // Identify initial coarse bins with significant grain values
  std::vector<int> significantRows, significantCols;
  adaptiveSampling ( coarseBins,
                     threshold,
                     significantRows,
                     true,
                     0 ); // Rows
  adaptiveSampling ( coarseBins,
                     threshold,
                     significantCols,
                     false,
                     0 );  // Columns

  // Iterative Refinement
  for ( int iter = 0; iter < maxIterations; iter++ )
  {
    std::vector<int> refinedRows, refinedCols;
    for ( int row : significantRows )
    {
      adaptiveSampling ( refineBins,
                         threshold,
                         refinedRows,
                         true,
                         row );
    }
    for ( int col : significantCols )
    {
      adaptiveSampling ( refineBins,
                         threshold,
                         refinedCols,
                         false,
                         col );
    }
    significantRows = refinedRows;
    significantCols = refinedCols;
  }

  // Determine cut-off frequencies from the refined significant bins
  int cutoffVertical = significantRows.empty() ? 0 : significantRows.back() / ( DATA_BASE_SIZE / 16 );
  int cutoffHorizontal = significantCols.empty() ? 0 : significantCols.back() / ( DATA_BASE_SIZE / 16 );

  // Set the cut-off frequencies in the model
  if ( cutoffVertical && cutoffHorizontal )
  {
    m_compModel[compId].presentFlag = true;
    m_compModel[compId].numModelValues = 3;
    m_compModel[compId].intensityValues[0].compModelValue[1] = cutoffHorizontal;
    m_compModel[compId].intensityValues[0].compModelValue[2] = cutoffVertical;
  }
  else
  {
    m_compModel[compId].presentFlag = false;
  }
}

// DCT-2 64x64 as defined in VVC
void FGAnalyzer::blockTransform ( CoeffBuf &currentCoeffBuf,
                                  int offsetX,
                                  int offsetY,
                                  uint32_t bitDepth,
                                  ComponentID compId )
{
  uint32_t      windowSize      = DATA_BASE_SIZE;   // Size for Film Grain block
  const int     transform_scale = 9;                // upscaling of original transform as specified in VVC (for 64x64 block)

  // copy input -> 32 Bit
  for ( uint32_t y = 0; y < DATA_BASE_SIZE; y++ )
  {
    for ( uint32_t x = 0; x < DATA_BASE_SIZE; x++ )
    {
      m_DCTinout[x + DATA_BASE_SIZE * y] = m_grainEstimateBuf->get( compId ).at( offsetX + x,
                                                                                 offsetY + y );
    }
  }

  fastForwardDCT2_B64 ( m_DCTinout,
                        m_DCTtemp,
                        transform_scale,
                        windowSize,
                        0,
                        0 );
  fastForwardDCT2_B64 ( m_DCTtemp,
                        m_DCTinout,
                        transform_scale,
                        windowSize,
                        0,
                        0 );

  // Calculate squared transformed block
  for ( int y = 0; y < DATA_BASE_SIZE; y++ )
  {
    for ( int x = 0; x < DATA_BASE_SIZE; x++ )
    {
      currentCoeffBuf.at( x, y ) = m_DCTinout[x + DATA_BASE_SIZE * y] * m_DCTinout[x + DATA_BASE_SIZE * y];
    }
  }
}

// check edges
int FGAnalyzer::countEdges ( int windowSize,
                             int offsetX,
                             int offsetY, 
                             ComponentID compId )
{
  for ( int x = 0; x < windowSize; x++ )
  {
    for ( int y = 0; y < windowSize; y++ )
    {
      if ( m_maskBuf->get( compId ).at( offsetX + x,
                                        offsetY + y ) )
      {
        return 0;
      }
    }
  }

  return 1;
}

// Fit data to a function using n-th order polynomial interpolation
bool FGAnalyzer::fitFunction ( int order,
                               int bitDepth,
                               bool second_pass )
{
  long double         a[MAXPAIRS + 1][MAXPAIRS + 1];
  long double         B[MAXPAIRS + 1], C[MAXPAIRS + 1], S[MAXPAIRS + 1];
  long double         A1 = 0.0, A2 = 0.0, Y1 = 0.0, m = 0.0, S1 = 0.0, x1 = 0.0;
  long double         xscale = 0.0, yscale = 0.0;
  long double         xmin = 0.0, xmax = 0.0, ymin = 0.0, ymax = 0.0;
  long double         polycoefs[MAXORDER + 1];
  int i, j, k, L, R;

  // several data filtering and data manipulations before fitting the function
  // create interval points for function fitting
  int INTENSITY_INTERVAL_NUMBER = (1 << bitDepth) / INTERVAL_SIZE;
  vec_mean_intensity.resize( INTENSITY_INTERVAL_NUMBER, 0 );
  vec_variance_intensity.resize( INTENSITY_INTERVAL_NUMBER, 0 );
  element_number_per_interval.resize( INTENSITY_INTERVAL_NUMBER, 0 );

  double              mn = 0.0, sd = 0.0;

  std::memset( a, 0, sizeof(a) );
  std::memset( B, 0, sizeof(B) );
  std::memset( C, 0, sizeof(C) );
  std::memset( S, 0, sizeof(S) );
  std::memset( polycoefs, 0, sizeof(polycoefs) );

  if ( second_pass )   // in second pass, filter based on the variance of the data_y. remove all high and low points
  {
    xmin = scalingVec.back();
    scalingVec.pop_back();
    xmax = scalingVec.back();
    scalingVec.pop_back();
    int n = static_cast<int>( vecVar.size() );
    if ( n != 0 )
    {
      mn = std::accumulate ( vecVar.begin(), vecVar.end(), 0.0 ) / n;
      for ( int cnt = 0; cnt < n; cnt++ )
      {
        sd += ( vecVar[cnt] - mn ) * ( vecVar[cnt] - mn );
      }
      sd /= n;
      sd = std::sqrt( sd );
    }
  }

  for ( int cnt = 0; cnt < vecMean.size(); cnt++ )
  {
    if ( second_pass )
    {
      if ( vecMean[cnt] >= xmin && vecMean[cnt] <= xmax )
      {
        if (( vecVar[cnt] < scalingVec[vecMean[cnt] - static_cast<int>(xmin)] + sd * VAR_SCALE_UP ) && ( vecVar[cnt] > scalingVec[vecMean[cnt] - static_cast<int>(xmin)] - sd * VAR_SCALE_DOWN ))
        {
          int block_index = vecMean[cnt] / INTERVAL_SIZE;
          vec_mean_intensity[block_index] += vecMean[cnt];
          vec_variance_intensity[block_index] += vecVar[cnt];
          element_number_per_interval[block_index]++;
        }
      }
    }
    else
    {
      int block_index = vecMean[cnt] / INTERVAL_SIZE;
      vec_mean_intensity[block_index] += vecMean[cnt];
      vec_variance_intensity[block_index] += vecVar[cnt];
      element_number_per_interval[block_index]++;
    }
  }

  // create points per intensity interval
  for ( int block_idx = 0; block_idx < INTENSITY_INTERVAL_NUMBER; block_idx++ )
  {
    if ( element_number_per_interval[block_idx] >= MIN_ELEMENT_NUMBER_PER_INTENSITY_INTERVAL )
    {
      tmp_data_x.push_back ( vec_mean_intensity[block_idx] / element_number_per_interval[block_idx] );
      tmp_data_y.push_back( vec_variance_intensity[block_idx] / element_number_per_interval[block_idx] );
    }
  }

  // There needs to be at least ORDER+1 points to fit the function
  if ( tmp_data_x.size() < ( order + 1 ) )
  {
    return false;   // if there is no enough blocks to estimate film grain parameters, default or previously estimated
                    // parameters are used
  }

  for ( i = 0; i < tmp_data_x.size(); i++ ) // remove single points before extending and fitting
  {
    int check = 0;
    for ( j = -WINDOW; j <= WINDOW; j++ )
    {
      int idx = i + j;
      if ( idx >= 0 && idx < tmp_data_x.size() && j != 0 )
      {
        check += abs( tmp_data_x[i] / INTERVAL_SIZE - tmp_data_x[idx] / INTERVAL_SIZE ) <= WINDOW ? 1 : 0;
      }
    }

    if ( check < NBRS )
    {
      for ( int k = i; k < tmp_data_x.size() - 1; k++ )
      {
        tmp_data_x[k] = tmp_data_x[k + 1];
        tmp_data_y[k] = tmp_data_y[k + 1];
      }
      tmp_data_x.pop_back();
      tmp_data_y.pop_back();
      i--;
    }
  }

  extendPoints( bitDepth );     // find the most left and the most right point, and extend edges

  CHECK( tmp_data_x.size() > MAXPAIRS, "Maximum dataset size exceeded." );

  // fitting the function starts here
  xmin = tmp_data_x[0];
  xmax = tmp_data_x[0];
  ymin = tmp_data_y[0];
  ymax = tmp_data_y[0];
  for ( i = 0; i < tmp_data_x.size(); i++ )
  {
    if ( tmp_data_x[i] < xmin )
    {
      xmin = tmp_data_x[i];
    }
    if ( tmp_data_x[i] > xmax )
    {
      xmax = tmp_data_x[i];
    }
    if ( tmp_data_y[i] < ymin )
    {
      ymin = tmp_data_y[i];
    }
    if ( tmp_data_y[i] > ymax )
    {
      ymax = tmp_data_y[i];
    }
  }

  long double xlow = xmax;
  long double ylow = ymax;

  int data_pairs = static_cast<int>( tmp_data_x.size() );

  double data_array[2][MAXPAIRS + 1];
  std::memset( data_array, 0, sizeof(data_array) );
  for ( i = 0; i < data_pairs; i++ )
  {
    data_array[0][i + 1] = static_cast<double>( tmp_data_x[i] );
    data_array[1][i + 1] = static_cast<double>( tmp_data_y[i] );
  }

  // Clear previous vectors by resizing them to 0
  tmp_data_x.clear();
  tmp_data_y.clear();

  if ( second_pass )
  {
    coeffs.resize( 0 );
    scalingVec.resize( 0 );
  }

  for ( i = 1; i <= data_pairs; i++ )
  {
    if ( data_array[0][i] < xlow && data_array[0][i] != 0 )
    {
      xlow = data_array[0][i];
    }
    if ( data_array[1][i] < ylow && data_array[1][i] != 0 )
    {
      ylow = data_array[1][i];
    }
  }

  if ( xlow < .001 && xmax < 1000 )
  {
    xscale = 1 / xlow;
  }
  else if ( xmax > 1000 && xlow > .001 )
  {
    xscale = 1 / xmax;
  }
  else
  {
    xscale = 1;
  }

  if ( ylow < .001 && ymax < 1000 )
  {
    yscale = 1 / ylow;
  }
  else if ( ymax > 1000 && ylow > .001 )
  {
    yscale = 1 / ymax;
  }
  else
  {
    yscale = 1;
  }

  // initialise array variables
  for ( j = 1; j <= data_pairs; j++ )
  {
    for ( i = 1; i <= order; i++ )
    {
      B[i] = B[i] + data_array[1][j] * yscale * ldpow( data_array[0][j] * xscale, i );
      if ( B[i] == std::numeric_limits<long double>::max() )
      {
        return false;
      }
      for ( k = 1; k <= order; k++ )
      {
        a[i][k] = a[i][k] + ldpow( data_array[0][j] * xscale, ( i + k ) );
        if ( a[i][k] == std::numeric_limits<long double>::max() )
        {
          return false;
        }
      }
      S[i] = S[i] + ldpow( data_array[0][j] * xscale, i );
      if ( S[i] == std::numeric_limits<long double>::max() )
      {
        return false;
      }
    }
    Y1 = Y1 + data_array[1][j] * yscale;
    if ( Y1 == std::numeric_limits<long double>::max() )
    {
      return false;
    }
  }

  for ( i = 1; i <= order; i++ )
  {
    for ( j = 1; j <= order; j++ )
    {
      a[i][j] = a[i][j] - S[i] * S[j] / static_cast<long double>( data_pairs );
      if (a[i][j] == std::numeric_limits<long double>::max())
      {
        return false;
      }
    }
    B[i] = B[i] - Y1 * S[i] / static_cast<long double>( data_pairs );
    if ( B[i] == std::numeric_limits<long double>::max() )
    {
      return false;
    }
  }

  for ( k = 1; k <= order; k++ )
  {
    R  = k;
    A1 = 0;
    for ( L = k; L <= order; L++ )
    {
      A2 = fabsl( a[L][k] );
      if ( A2 > A1 )
      {
        A1 = A2;
        R  = L;
      }
    }
    if ( A1 == 0 )
    {
      return false;
    }
    if ( R != k )
    {
      for ( j = k; j <= order; j++ )
      {
        x1      = a[R][j];
        a[R][j] = a[k][j];
        a[k][j] = x1;
      }
      x1   = B[R];
      B[R] = B[k];
      B[k] = x1;
    }
    for ( i = k; i <= order; i++ )
    {
      m = a[i][k];
      for ( j = k; j <= order; j++ )
      {
        if ( i == k )
        {
          a[i][j] = a[i][j] / m;
        }
        else
        {
          a[i][j] = a[i][j] - m * a[k][j];
        }
      }
      if ( i == k )
      {
        B[i] = B[i] / m;
      }
      else
      {
        B[i] = B[i] - m * B[k];
      }
    }
  }

  polycoefs[order] = B[order];
  for ( k = 1; k <= order - 1; k++ )
  {
    i  = order - k;
    S1 = 0;
    for ( j = 1; j <= order; j++ )
    {
      S1 = S1 + a[i][j] * polycoefs[j];
      if ( S1 == std::numeric_limits<long double>::max() )
      {
        return false;
      }
    }
    polycoefs[i] = B[i] - S1;
  }

  S1 = 0;
  for ( i = 1; i <= order; i++ )
  {
    S1 = S1 + polycoefs[i] * S[i] / static_cast<long double>( data_pairs );
    if ( S1 == std::numeric_limits<long double>::max() )
    {
      return false;
    }
  }
  polycoefs[0] = (Y1 / static_cast<long double>( data_pairs ) - S1);

  // zero all coeficient values smaller than +/- .00000000001 (avoids -0)
  for ( i = 0; i <= order; i++ )
  {
    if ( fabsl(polycoefs[i] * 100000000000) < 1 )
    {
      polycoefs[i] = 0;
    }
  }

  // rescale parameters
  for ( i = 0; i <= order; i++ )
  {
    polycoefs[i] = (1 / yscale) * polycoefs[i] * ldpow( xscale, i );
    coeffs.push_back( polycoefs[i] );
  }

  // create fg scaling function. interpolation based on coeffs which returns lookup table from 0 - 2^B-1. n-th order polinomial regression
  for ( i = static_cast<int>( xmin ); i <= static_cast<int>( xmax ); i++ )
  {
    double val = coeffs[0];
    for ( j = 1; j < coeffs.size(); j++ )
    {
      val += (coeffs[j] * ldpow( i, j ));
    }

    val = Clip3( 0.0,
                 static_cast<double>( 1 << bitDepth ) - 1,
                 val );
    scalingVec.push_back( val );
  }

  // save in scalingVec min and max value for further use
  scalingVec.push_back( xmax );
  scalingVec.push_back( xmin );

  vec_mean_intensity.clear();
  vec_variance_intensity.clear();
  element_number_per_interval.clear();
  tmp_data_x.clear();
  tmp_data_y.clear();

  return true;
}

// avg scaling vector with previous result to smooth transition betweeen frames
void FGAnalyzer::avgScalingVec ( int bitDepth )
{
  int xmin = static_cast<int>( scalingVec.back() );
  scalingVec.pop_back();
  int xmax = static_cast<int>( scalingVec.back() );
  scalingVec.pop_back();

  std::vector<double> scalingVecAvg( static_cast<int>( 1 << bitDepth ) );
  bool isFirstScalingEst = true;

  if ( isFirstScalingEst )
  {
    for (int i = xmin; i <= xmax; i++)
    {
      scalingVecAvg[i] = scalingVec[i - xmin];
    }
    isFirstScalingEst = false;
  }
  else
  {
    for ( int i = xmin; i <= xmax; i++ )
    {
      scalingVecAvg[i] = ( scalingVecAvg[i] + scalingVec[i - xmin] ) / 2.0;
    }
  }

  int new_xmin = 0;
  while ( new_xmin <= xmax && scalingVecAvg[new_xmin] == 0 )
  {
    new_xmin++;
  }

  int new_xmax = static_cast<int>( scalingVecAvg.size() ) - 1;
  while ( new_xmax >= 0 && scalingVecAvg[new_xmax] == 0 )
  {
    new_xmax--;
  }

  if ( new_xmax < new_xmin )
  {
    // Handle the case where all entries are zero
    scalingVec.clear();
    scalingVec.push_back( 0 ); // Minimum value
    scalingVec.push_back( 0 ); // Maximum value
    return;
  }

  scalingVec.assign( scalingVecAvg.begin() + new_xmin,
                     scalingVecAvg.begin() + new_xmax + 1 );
  scalingVec.push_back( new_xmax );
  scalingVec.push_back( new_xmin );
}


// Lloyd Max quantizer
bool FGAnalyzer::lloydMax ( double &distortion,
                            int bitDepth )
{
  if ( !scalingVec.size() )
  {
    // Film grain parameter estimation is not performed. Default or previously estimated parameters are reused.
    return false;
  }

  int xmin = static_cast<int>( scalingVec.back() );
  scalingVec.pop_back();
  scalingVec.pop_back();   // dummy pop_pack ==> int xmax = (int)scalingVec.back();

  double ymin          = 0.0;
  double ymax          = 0.0;
  double init_training = 0.0;
  double tolerance     = 0.0000001;
  double last_distor   = 0.0;
  double rel_distor    = 0.0;

  double codebook[QUANT_LEVELS];
  double partition[QUANT_LEVELS - 1];

  std::vector<double> tmpVec( scalingVec.size(), 0.0 );
  distortion = 0.0;

  ymin = scalingVec[0];
  ymax = scalingVec[0];
  for ( int i = 0; i < scalingVec.size(); i++ )
  {
    if ( scalingVec[i] < ymin )
    {
      ymin = scalingVec[i];
    }
    if ( scalingVec[i] > ymax )
    {
      ymax = scalingVec[i];
    }
  }

  init_training = ( ymax - ymin ) / QUANT_LEVELS;

  if ( init_training <= 0 )
  {
    // msg(WARNING, "Invalid training dataset. Film grain parameter estimation is not performed. Default or previously estimated parameters are reused.\n");
    return false;
  }

  // initial codebook
  double step = init_training / 2;
  for ( int i = 0; i < QUANT_LEVELS; i++ )
  {
    codebook[i] = ymin + i * init_training + step;
  }

  // initial partition
  for ( int i = 0; i < QUANT_LEVELS - 1; i++ )
  {
    partition[i] = (codebook[i] + codebook[i + 1]) / 2;
  }

  // quantizer initialization
  quantize ( tmpVec,
             distortion,
             partition,
             codebook );

  double tolerance2 = std::numeric_limits<double>::epsilon() * ymax;
  if ( distortion > tolerance2 )
  {
    rel_distor = std::fabs( distortion - last_distor ) / distortion;
  }
  else
  {
    rel_distor = distortion;
  }

  // optimization: find optimal codebook and partition
  while ( ( rel_distor > tolerance ) && ( rel_distor > tolerance2 ) )
  {
    for ( int i = 0; i < QUANT_LEVELS; i++ )
    {
      int count = 0;
      double sum = 0.0;

      for ( int j = 0; j < tmpVec.size(); j++ )
      {
        if ( codebook[i] == tmpVec[j] )
        {
          count++;
          sum += scalingVec[j];
        }
      }

      if ( count )
      {
        codebook[i] = sum / static_cast<double>( count );
      }
      else
      {
        sum   = 0.0;
        count = 0;
        if ( i == 0 )
        {
          for ( int j = 0; j < tmpVec.size(); j++ )
          {
            if ( scalingVec[j] <= partition[i] )
            {
              count++;
              sum += scalingVec[j];
            }
          }
          if ( count )
          {
            codebook[i] = sum / static_cast<double>( count );
          }
          else
          {
            codebook[i] = ( partition[i] + ymin ) / 2;
          }
        }
        else if ( i == QUANT_LEVELS - 1 )
        {
          for ( int j = 0; j < tmpVec.size(); j++ )
          {
            if (scalingVec[j] >= partition[i - 1])
            {
              count++;
              sum += scalingVec[j];
            }
          }
          if ( count )
          {
            codebook[i] = sum / static_cast<double>( count );
          }
          else
          {
            codebook[i] = ( partition[i - 1] + ymax ) / 2;
          }
        }
        else
        {
          for ( int j = 0; j < tmpVec.size(); j++ )
          {
            if ( scalingVec[j] >= partition[i - 1] && scalingVec[j] <= partition[i] )
            {
              count++;
              sum += scalingVec[j];
            }
          }
          if ( count )
          {
            codebook[i] = sum / static_cast<double>( count );
          }
          else
          {
            codebook[i] = ( partition[i - 1] + partition[i] ) / 2;
          }
        }
      }
    }

    // compute and sort partition
    for ( int i = 0; i < QUANT_LEVELS - 1; i++ )
    {
      partition[i] = ( codebook[i] + codebook[i + 1] ) / 2;
    }
    std::sort( partition, partition + QUANT_LEVELS - 1 );

    // final quantization - testing condition
    last_distor = distortion;
    quantize ( tmpVec,
               distortion,
               partition,
               codebook );

    if ( distortion > tolerance2 )
    {
      rel_distor = std::fabs( distortion - last_distor ) / distortion;
    }
    else
    {
      rel_distor = distortion;
    }
  }

  // fill the final quantized vector
  int maxVal = ( 1 << bitDepth ) - 1;  // Full range max value for given bit depth
  quantVec.resize( static_cast<int>( 1 << bitDepth ), 0 );
  for ( int i = 0; i < tmpVec.size(); i++ )
  {
    quantVec[i + xmin] = Clip3( 0, 
                                maxVal,                                    
                                static_cast<int>( tmpVec[i] + 0.5 ) );
  }

  return true;
}

void FGAnalyzer::quantize ( std::vector<double>& quantizedVec,
                            double& distortion,
                            double partition[],
                            double codebook[] )
{
  // Reset previous quantizedVec to 0 and distortion to 0
  std::fill(quantizedVec.begin(), quantizedVec.end(), 0.0);
  distortion = 0.0;

  // Quantize input vector
  for ( int i = 0; i < scalingVec.size(); i++ )
  {
    double quantizedValue = 0.0;
    for ( int j = 0; j < QUANT_LEVELS - 1; j++ )
    {
      quantizedValue += ( scalingVec[i] > partition[j] );
    }
    quantizedVec[i] = codebook[static_cast<int>( quantizedValue )];
  }

  // Compute distortion (MSE)
  for ( int i = 0; i < scalingVec.size(); i++ )
  {
    double error = scalingVec[i] - quantizedVec[i];
    distortion += ( error * error );
  }
  distortion /= scalingVec.size();
}

// Set correctlly SEI parameters based on the quantized curve
void FGAnalyzer::setEstimatedParameters ( uint32_t bitDepth,
                                          ComponentID compId )
{
  // calculate intervals and scaling factors
  defineIntervalsAndScalings ( bitDepth );

  // Merge small intervals with left or right interval
  for ( size_t i = 0; i < finalIntervalsandScalingFactors.size(); ++i )
  {
    int tmp1 = finalIntervalsandScalingFactors[i][1] - finalIntervalsandScalingFactors[i][0];

    if ( tmp1 < ( 2 << ( bitDepth - BIT_DEPTH_8 ) ) )
    {
      int diffRight = ( i == finalIntervalsandScalingFactors.size() - 1 ) || ( finalIntervalsandScalingFactors[i + 1][2] == 0 )
          ? std::numeric_limits<int>::max()
          : abs( finalIntervalsandScalingFactors[i][2] - finalIntervalsandScalingFactors[i + 1][2] );
      int diffLeft = ( i == 0 ) || ( finalIntervalsandScalingFactors[i - 1][2] == 0 )
          ? std::numeric_limits<int>::max()
          : abs( finalIntervalsandScalingFactors[i][2] - finalIntervalsandScalingFactors[i - 1][2] );

      if ( diffLeft < diffRight )
      {
        int tmp2 = finalIntervalsandScalingFactors[i - 1][1] - finalIntervalsandScalingFactors[i - 1][0];
        int newScale = ( tmp2 * finalIntervalsandScalingFactors[i - 1][2] + tmp1 * finalIntervalsandScalingFactors[i][2] ) / ( tmp2 + tmp1 );

        finalIntervalsandScalingFactors[i - 1][1] = finalIntervalsandScalingFactors[i][1];
        finalIntervalsandScalingFactors[i - 1][2] = newScale;
        finalIntervalsandScalingFactors.erase( finalIntervalsandScalingFactors.begin() + i );
        --i;
      }
      else
      {
        int tmp2 = finalIntervalsandScalingFactors[i + 1][1] - finalIntervalsandScalingFactors[i + 1][0];
        int newScale = ( tmp2 * finalIntervalsandScalingFactors[i + 1][2] + tmp1 * finalIntervalsandScalingFactors[i][2] ) / ( tmp2 + tmp1 );

        finalIntervalsandScalingFactors[i][1] = finalIntervalsandScalingFactors[i + 1][1];
        finalIntervalsandScalingFactors[i][2] = newScale;
        finalIntervalsandScalingFactors.erase( finalIntervalsandScalingFactors.begin() + i + 1 );
        --i;
      }
    }
  }

  // scale to 8-bit range as supported by current sei and rdd5
  scaleDown ( bitDepth );

  // because of scaling in previous step, some intervals may overlap. Check intervals for errors.
  confirmIntervals ( );

  // Set number of intervals; exclude intervals with scaling factor 0.
  m_compModel[compId].numIntensityIntervals =
      static_cast<uint8_t>( finalIntervalsandScalingFactors.size() - std::count_if ( finalIntervalsandScalingFactors.begin(),
                                                                                     finalIntervalsandScalingFactors.end(),
                                                                                     []( const std::array<int, 3>& interval )
                                                                                     {
                                                                                       return interval[2] == 0;
                                                                                     }
                                                                                   ) );

  // check if all intervals are 0, and if yes set presentFlag to false
  if ( m_compModel[compId].numIntensityIntervals == 0 )
  { 
    m_compModel[compId].presentFlag = false;
    return;
  }

  // Set final interval boundaries and scaling factors.
  // Check if some interval has scaling factor 0, and do not encode them within SEI.
  int j = 0;
  for ( const auto& interval : finalIntervalsandScalingFactors )
  {
    if ( interval[2] != 0 )
    {
      m_compModel[compId].intensityValues[j].intensityIntervalLowerBound = interval[0];
      m_compModel[compId].intensityValues[j].intensityIntervalUpperBound = interval[1];
      m_compModel[compId].intensityValues[j].compModelValue[0] = interval[2];
      m_compModel[compId].intensityValues[j].compModelValue[1] = m_compModel[compId].intensityValues[0].compModelValue[1];
      m_compModel[compId].intensityValues[j].compModelValue[2] = m_compModel[compId].intensityValues[0].compModelValue[2];
      ++j;
    }
  }
  CHECK( j != m_compModel[compId].numIntensityIntervals, "Check film grain intensity levels" );
}

long double FGAnalyzer::ldpow ( long double n,
                                unsigned p )
{
  long double result = 1.0;

  // Handle special cases for p = 0 and p = 1
  if ( p == 0 ) return 1.0;
  if ( p == 1 ) return n;

  // Exponentiation by squaring
  while ( p > 0 )
  {
    if ( p % 2 == 1 )
      result *= n;
    n *= n;
    p /= 2;
  }
  return result;
}

// find bounds of intensity intervals and scaling factors for each interval
void FGAnalyzer::defineIntervalsAndScalings ( int bitDepth )
{
  finalIntervalsandScalingFactors.clear();
  std::array<int, 3> interval = { 0, 0, quantVec[0] };

  for ( int i = 0; i < (1 << bitDepth) - 1; ++i )
  {
    if ( quantVec[i] != quantVec[i + 1] )
    {
      interval[1] = i;
      finalIntervalsandScalingFactors.push_back ( interval );
      interval[0] = i + 1;
      interval[2] = quantVec[i + 1];
    }
  }
  interval[1] = ( 1 << bitDepth ) - 1;
  finalIntervalsandScalingFactors.push_back ( interval );
}

// scale everything to 8-bit ranges as supported by SEI message
void FGAnalyzer::scaleDown ( int bitDepth )
{
  for ( auto& interval : finalIntervalsandScalingFactors )
  {
    interval[0] >>= ( bitDepth - BIT_DEPTH_8 );
    interval[1] >>= ( bitDepth - BIT_DEPTH_8 );
    interval[2] <<= m_log2ScaleFactor;
    interval[2] >>= ( bitDepth - BIT_DEPTH_8 );
  }
}

// check if intervals are properly set after scaling to 8-bit representation
void FGAnalyzer::confirmIntervals ( )
{
  for ( size_t i = 0; i < finalIntervalsandScalingFactors.size() - 1; ++i )
  {
    if ( finalIntervalsandScalingFactors[i][1] >= finalIntervalsandScalingFactors[i + 1][0] )
    {
      finalIntervalsandScalingFactors[i][1] = finalIntervalsandScalingFactors[i + 1][0] - 1;
    }
  }
}

void FGAnalyzer::extendPoints ( int bitDepth )
{
  int xmin = tmp_data_x[0];
  int xmax = tmp_data_x[0];
  int ymin = tmp_data_y[0];
  int ymax = tmp_data_y[0];
  for ( int i = 0; i < tmp_data_x.size(); i++ )
  {
    if ( tmp_data_x[i] < xmin )
    {
      xmin = tmp_data_x[i];
      ymin = tmp_data_y[i];   // not real ymin
    }
    if ( tmp_data_x[i] > xmax )
    {
      xmax = tmp_data_x[i];
      ymax = tmp_data_y[i];   // not real ymax
    }
  }

  // extend points to the left
  int    step = POINT_STEP;
  double scale = POINT_SCALE;
  int num_extra_point_left = MAX_NUM_POINT_TO_EXTEND;
  int num_extra_point_right = MAX_NUM_POINT_TO_EXTEND;
  while ( xmin >= step && ymin > 1 && num_extra_point_left > 0 )
  {
    xmin -= step;
    ymin = static_cast<int>( ymin / scale );
    tmp_data_x.push_back( xmin );
    tmp_data_y.push_back( ymin );
    num_extra_point_left--;
  }

  // extend points to the right
  while ( xmax + step <= ((1 << bitDepth) - 1) && ymax > 1 && num_extra_point_right > 0 )
  {
    xmax += step;
    ymax = static_cast<int>( ymax / scale );
    tmp_data_x.push_back( xmax );
    tmp_data_y.push_back( ymax );
    num_extra_point_right--;
  }

  // filter out points outside the range
  auto isValid = []( int x )
  {
    return x >= MIN_INTENSITY && x <= MAX_INTENSITY;
  };

  std::vector<int> valid_x, valid_y;
  for ( int i = 0; i < tmp_data_x.size(); i++ )
  {
    if ( isValid( tmp_data_x[i] ) )
    {
      valid_x.push_back( tmp_data_x[i] );
      valid_y.push_back( tmp_data_y[i] );
    }
  }
  tmp_data_x = std::move( valid_x );
  tmp_data_y = std::move( valid_y );
}


Coverage Report

Created: 2026-07-16 06:32