From 83bc6140bdaf19d73ecdd7539cfa76bd15d50e2a Mon Sep 17 00:00:00 2001
From: heckflosse <heckflosse67@gmx.de>
Date: Thu, 25 Jan 2018 21:27:10 +0100
Subject: [PATCH] Avoid Lab L values which lead to negative Y values when
 converting Lab to XYZ, fixes #4334

---
 rtengine/iplocalcontrast.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtengine/iplocalcontrast.cc b/rtengine/iplocalcontrast.cc
index 24739fb6b..aa1eeff7d 100644
--- a/rtengine/iplocalcontrast.cc
+++ b/rtengine/iplocalcontrast.cc
@@ -62,7 +62,7 @@ void ImProcFunctions::localContrast(LabImage *lab)
                 bufval *= (bufval > 0.f) ? light : dark;
             }
 
-            lab->L[y][x] += bufval;
+            lab->L[y][x] = std::max(0.0001f, lab->L[y][x] + bufval);
         }
     }
 }