augment contaminated brackets

src/aliceVision/hdr/brackets.cpp

@@ -303,6 +303,42 @@ std::vector<std::vector<LuminanceInfo>> splitMonotonics(const std::vector<Lumina
     return splitted;
 }
 
+/**
+* @brief assume ref is smaller than larger
+* Try to find a subpart of larger which has the same set of exposures that smaller
+* @param smaller the set to compare
+* @param larger the set where the subpart should be
+* @return the index of the subpart or -1 if not found
+*/
+int extractIndex(const std::vector<LuminanceInfo> & smaller, const std::vector<LuminanceInfo> & larger)
+{
+    int largerSize = larger.size();
+    int smallerSize = smaller.size();
+    int diff = largerSize - smallerSize;
+
+    //For all continuous subparts of the erased sequence
+    for (int indexStart = 0; indexStart < diff; indexStart++)
+    {
+        //Check that the subpart is the same set of exposures
+        bool allCorrect = true;
+        for (int pos = 0; pos < smallerSize; pos++)
+        {
+            if (smaller[pos].mexposure != larger[indexStart + pos].mexposure)
+            {
+                allCorrect = false;
+            }
+        }
+
+        if (allCorrect)
+        {
+            return indexStart;
+        }
+    }
+
+    return -1;
+}
+
+
 std::vector<std::vector<IndexT>> estimateGroups(const std::vector<LuminanceInfo> & luminanceInfos)
 {
     std::vector<std::vector<IndexT>> groups;
@@ -321,6 +357,16 @@ std::vector<std::vector<IndexT>> estimateGroups(const std::vector<LuminanceInfo>
         monotonics.insert(monotonics.end(), lmonotonics.begin(), lmonotonics.end());
     }
 
+    //Sort the voters groups by exposure increasing
+    for (auto & group : monotonics)
+    {
+        std::sort(group.begin(), 
+                  group.end(), 
+                  [](const LuminanceInfo& a, const LuminanceInfo& b) {
+                    return (a.mexposure < b.mexposure);
+                  });
+    }
+
     // Vote for the best bracket count
     std::map<size_t, int> counters;
     for (const auto& group : monotonics)
@@ -355,10 +401,12 @@ std::vector<std::vector<IndexT>> estimateGroups(const std::vector<LuminanceInfo>
 
     // Only keep voters with the majority bracket size
     auto groupIt = monotonics.begin();
+    std::vector<std::vector<LuminanceInfo>> eraseds;
     while (groupIt != monotonics.end())
     {
         if (groupIt->size() != bestBracketCount)
         {
+            eraseds.push_back(*groupIt);
             groupIt = monotonics.erase(groupIt);
         }
         else
@@ -367,14 +415,39 @@ std::vector<std::vector<IndexT>> estimateGroups(const std::vector<LuminanceInfo>
         }
     }
 
-    //Sort the voters groups by exposure increasing
-    for (auto & group : monotonics)
+    //Try to push back erased
+    for (const auto & erased: eraseds)
     {
-        std::sort(group.begin(), 
-                  group.end(), 
-                  [](const LuminanceInfo& a, const LuminanceInfo& b) {
-                    return (a.mexposure < b.mexposure);
-                  });
+        //If erased is larger than the most voted, then 
+        //Maybe it contains outliers. Try to find a correct subpart
+        int diff = int(erased.size()) - bestBracketCount;
+        if (diff < 0)
+        {
+            continue;
+        }
+
+
+        //Compare with all valid monotonics
+        int offset = -1;
+        for (const auto& monotonic : monotonics)
+        {
+            offset = extractIndex(monotonic, erased);
+            if (offset >= 0)
+            {
+                break;
+            }
+        }
+
+        //If something found, put it back on list of monotonics
+        if (offset >= 0)
+        {
+            std::vector<LuminanceInfo> subpart;
+            for (int index = 0; index < bestBracketCount; index++)
+            {
+                subpart.push_back(erased[offset + index]);
+            }
+            monotonics.push_back(subpart);
+        }
     }
 
     //check coherency
@@ -411,6 +484,8 @@ std::vector<std::vector<IndexT>> estimateGroups(const std::vector<LuminanceInfo>
         groups.push_back(group);
     }
 
+    ALICEVISION_LOG_INFO("Groups found : "  << monotonics.size());
+
     return groups;
 }