From 7b058696133c6d36e0b48a454e357482db71982e Mon Sep 17 00:00:00 2001
From: Cristy <urban-warrior@imagemagick.org>
Date: Fri, 11 Oct 2019 20:20:19 -0400
Subject: [PATCH] https://github.com/ImageMagick/ImageMagick/issues/1740

---
 MagickCore/quantize.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/MagickCore/quantize.c b/MagickCore/quantize.c
index d65cb2d7e2f..38ea0d3e755 100644
--- a/MagickCore/quantize.c
+++ b/MagickCore/quantize.c
@@ -2347,8 +2347,8 @@ MagickExport MagickBooleanType PosterizeImage(Image *image,const size_t levels,
   const DitherMethod dither_method,ExceptionInfo *exception)
 {
 #define PosterizeImageTag  "Posterize/Image"
-#define PosterizePixel(pixel) (Quantum) (QuantumRange*(MagickRound( \
-  QuantumScale*pixel*(levels-1)))/MagickMax((ssize_t) levels-1,1))
+#define PosterizePixel(pixel) ClampToQuantum((MagickRealType) QuantumRange*( \
+  MagickRound(QuantumScale*pixel*(levels-1)))/MagickMax((ssize_t) levels-1,1))
 
   CacheView
     *image_view;
@@ -3282,17 +3282,21 @@ extern "C" {
 
 static int IntensityCompare(const void *x,const void *y)
 {
+  double
+    intensity;
+
   PixelInfo
     *color_1,
     *color_2;
 
-  ssize_t
-    intensity;
-
   color_1=(PixelInfo *) x;
   color_2=(PixelInfo *) y;
-  intensity=(ssize_t) (GetPixelInfoIntensity((const Image *) NULL,color_1)-
-    GetPixelInfoIntensity((const Image *) NULL,color_2));
+  intensity=GetPixelInfoIntensity((const Image *) NULL,color_1)-
+    GetPixelInfoIntensity((const Image *) NULL,color_2);
+  if (intensity > (double) INT_MAX)
+    intensity=(double) INT_MAX;
+  if (intensity < (double) INT_MIN)
+    intensity=(double) INT_MIN;
   return((int) intensity);
 }