From eb307ea091ede87b6c4670763b4582f00f13b2b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Du=C5=A1an=20Poizl?= <nou.spiro@gmail.com>
Date: Sat, 28 Sep 2019 12:27:38 +0200
Subject: [PATCH] Optimize median calculation

---
 rawimage.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/rawimage.h b/rawimage.h
index 0ff1f8e..db2c34e 100644
--- a/rawimage.h
+++ b/rawimage.h
@@ -84,6 +84,9 @@ public:
         uint64_t sqrSum = 0;
         uint64_t tMin = UINT64_MAX;
         uint64_t tMax = 0;
+        uint32_t histogram[65536];
+        memset(histogram, 0, sizeof(histogram));
+        const int shift = sizeof(T)>2 ? sizeof(T)*8 - 16 : 0;
 
         for(T i : m_img)
         {
@@ -91,6 +94,7 @@ public:
             sqrSum += i*i;
             tMin = tMin>i ? i : tMin;
             tMax = tMax<i ? i : tMax;
+            histogram[i>>shift]++;
         }
 
         if(mean)*mean = sum/m_img.size();
@@ -98,14 +102,9 @@ public:
         if(max)*max = tMax;
         if(stdDev)*stdDev = sqrt((sqrSum - (double)sum*sum/m_img.size()) / (double)(m_img.size()-1));
 
-        const int shift = sizeof(T)>2 ? sizeof(T)*8 - 16 : 0;
 
         if(median)
         {
-            uint32_t histogram[65536];
-            memset(histogram, 0, sizeof(histogram));
-            for(T i : m_img)
-                histogram[i>>shift]++;
             size_t medianSum = 0;
             for(int i=0;i<65536;i++)
             {