JVET-O0272: CE2-related: Simplified inverse luma mapping

source/Lib/CommonLib/CommonDef.h

@@ -445,6 +445,9 @@ static constexpr int MV_MIN =                 -(1 << (MV_BITS - 1));
 
 static const int PIC_ANALYZE_CW_BINS =                           32;
 static const int PIC_CODE_CW_BINS =                              16;
+#if JVET_O0272_LMCS_SIMP_INVERSE_MAPPING
+static const int LMCS_SEG_SIZE =            (PIC_CODE_CW_BINS << 1);
+#endif
 static const int FP_PREC =                                       11;
 static const int CSCALE_FP_PREC =                                11;
 #if JVET_O1109_UNFIY_CRS

source/Lib/CommonLib/TypeDef.h

@@ -52,6 +52,8 @@
 
 #define JVET_O0216_ALF_COEFF_EG3                          1 // JVET-O0216/O0302/O0648: using EG3 for ALF coefficients coding
 
+#define JVET_O0272_LMCS_SIMP_INVERSE_MAPPING              1 // JVET-O0272: LMCS simplified inverse mapping
+
 #define JVET_O0247_ALF_CTB_CODING_REDUNDANCY_REMOVAL      1 // JVET-O0247: not signal APS index when number APS is 2
 
 #define JVET_O0637_CHROMA_GRADIENT_LINE_SELECTION         1 // Choose line0 and line3 for gradient computation when chroma is same size as luma

source/Lib/EncoderLib/EncReshape.cpp

@@ -1054,6 +1054,10 @@ void EncReshape::initLUTfromdQPModel()
   }
 #endif
 
+#if JVET_O0272_LMCS_SIMP_INVERSE_MAPPING
+  adjustLmcsPivot();
+#endif
+
   int maxAbsDeltaCW = 0, absDeltaCW = 0, deltaCW = 0;
   for (int i = m_sliceReshapeInfo.reshaperModelMinBinIdx; i <= m_sliceReshapeInfo.reshaperModelMaxBinIdx; i++)
   {
@@ -1261,6 +1265,11 @@ void EncReshape::constructReshaperSDR()
   {
     m_binCW[i] = m_binCW[2 * i] + m_binCW[2 * i + 1];
   }
+
+#if JVET_O0272_LMCS_SIMP_INVERSE_MAPPING
+  adjustLmcsPivot();
+#endif
+
   m_sliceReshapeInfo.reshaperModelMinBinIdx = 0;
   m_sliceReshapeInfo.reshaperModelMaxBinIdx = PIC_CODE_CW_BINS - 1;
   for (int i = 0; i < PIC_CODE_CW_BINS; i++)
@@ -1361,6 +1370,44 @@ void EncReshape::constructReshaperSDR()
 #endif
 }
 
+#if JVET_O0272_LMCS_SIMP_INVERSE_MAPPING
+void EncReshape::adjustLmcsPivot()
+{
+  int bdShift = m_lumaBD - 10;
+  int totCW = bdShift != 0 ? (bdShift > 0 ? m_reshapeLUTSize / (1 << bdShift) : m_reshapeLUTSize * (1 << (-bdShift))) : m_reshapeLUTSize;
+  int orgCW = totCW / PIC_CODE_CW_BINS;
+  int log2SegSize = g_aucLog2[LMCS_SEG_SIZE];
+  m_reshapePivot[0] = 0;
+  for (int i = 0; i < PIC_CODE_CW_BINS; i++)
+  {
+    m_reshapePivot[i+1] = m_reshapePivot[i] + m_binCW[i];
+    int segIdxCurr = (m_reshapePivot[i]     >> log2SegSize);
+    int segIdxNext = (m_reshapePivot[i + 1] >> log2SegSize);
+    if ((segIdxCurr == segIdxNext) && (m_reshapePivot[i] != m_reshapePivot[i + 1]) && (m_reshapePivot[i] != (segIdxCurr << log2SegSize)))
+    {
+      int16_t adjustVal = ((segIdxCurr + 1) << log2SegSize) - m_reshapePivot[i + 1];
+      m_reshapePivot[i + 1] += adjustVal;
+      m_binCW[i] += adjustVal;
+      for (int j = i + 1; j < PIC_CODE_CW_BINS; j++)
+      {
+        if (m_binCW[j] < (adjustVal + (orgCW >> 3)))
+        {
+          adjustVal -= (m_binCW[j] - (orgCW >> 3));
+          m_binCW[j] = (orgCW >> 3);
+        }
+        else
+        {
+          m_binCW[j] -= adjustVal;
+          adjustVal = 0;
+        }
+        if (adjustVal == 0)
+          break;
+      }
+    }
+  }
+}
+#endif
+
 #if ENABLE_SPLIT_PARALLELISM || ENABLE_WPP_PARALLELISM
 void EncReshape::copyState(const EncReshape &other)
 {

source/Lib/EncoderLib/EncReshape.h

@@ -93,6 +93,9 @@ public:
   ReshapeCW * getReshapeCW() { return &m_reshapeCW; }
   Pel * getWeightTable() { return m_cwLumaWeight; }
   double getCWeight() { return m_chromaWeight; }
+#if JVET_O0272_LMCS_SIMP_INVERSE_MAPPING
+  void adjustLmcsPivot();
+#endif
 
 #if ENABLE_SPLIT_PARALLELISM || ENABLE_WPP_PARALLELISM
   void copyState(const EncReshape& other);