From 74e31dff45293ca5e8ce3fe22c1d870eca290b65 Mon Sep 17 00:00:00 2001
From: Alberto Griggio <agriggio@users.noreply.github.com>
Date: Wed, 31 Jan 2018 18:09:28 +0100
Subject: [PATCH] histmatching: dynamically adjust the skip factor according to
 the side of the embedded thumbnail

with large the embedded thumbnails we should skip less to improve the quality of the matching
---
 rtengine/histmatching.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/rtengine/histmatching.cc b/rtengine/histmatching.cc
index e496f6f82..e326a3f7d 100644
--- a/rtengine/histmatching.cc
+++ b/rtengine/histmatching.cc
@@ -189,7 +189,7 @@ void RawImageSource::getAutoMatchedToneCurve(std::vector<double> &outCurve)
 
     int fw, fh;
     getFullSize(fw, fh, TR_NONE);
-    int skip = 10;
+    int skip = 3;
 
     if (settings->verbose) {
         std::cout << "histogram matching: full raw image size is " << fw << "x" << fh << std::endl;
@@ -213,6 +213,7 @@ void RawImageSource::getAutoMatchedToneCurve(std::vector<double> &outCurve)
             histMatchingCache = outCurve;
             return;
         }
+        skip = LIM(5, skip * fh / h, 10); // adjust the skip factor -- the larger the thumbnail, the less we should skip to get a good match
         source.reset(thumb->quickProcessImage(neutral, fh / skip, TI_Nearest));
 
         if (settings->verbose) {