https://github.com/ImageMagick/ImageMagick/issues/1712

diff --git a/MagickCore/quantum-private.h b/MagickCore/quantum-private.h
index dbea5ce982394a90ca30e1e633bcadaea57c90cd..76f0a9dc0a6d9adf0986a5fc9876f16e9f4109d1 100644 (file)
--- a/MagickCore/quantum-private.h
+++ b/MagickCore/quantum-private.h
@@ -324,6 +324,8 @@ static inline Quantum ScaleAnyToQuantum(const QuantumAny quantum,
 static inline QuantumAny ScaleQuantumToAny(const Quantum quantum,
   const QuantumAny range)
 {
+  if (quantum < 0)
+    return((QuantumAny) 0);
   return((QuantumAny) (((double) range*quantum)/QuantumRange+0.5));
 }