From: Cristy <urban-warrior@imagemagick.org>
Date: Sat, 5 Jan 2019 20:28:59 +0000 (-0500)
Subject: Do not use virtual pixels if image dimensions evenly divisible by tile dimensions
X-Git-Tag: 7.0.8-24~34
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b665c2707555823ad607dbe00e49f940c2fc1b10;p=imagemagick

Do not use virtual pixels if image dimensions evenly divisible by tile dimensions
---

diff --git a/MagickCore/enhance.c b/MagickCore/enhance.c
index ba91ffeab..773b516b0 100644
--- a/MagickCore/enhance.c
+++ b/MagickCore/enhance.c
@@ -659,8 +659,12 @@ MagickExport MagickBooleanType CLAHEImage(Image *image,const size_t width,
   tile_info.height=height;
   if (tile_info.height == 0)
     tile_info.height=image->rows >> 3;
-  tile_info.x=(ssize_t) tile_info.width-(image->columns % tile_info.width);
-  tile_info.y=(ssize_t) tile_info.height-(image->rows % tile_info.height);
+  tile_info.x=0;
+  if ((image->columns % tile_info.width) != 0)
+    tile_info.x=(ssize_t) tile_info.width-(image->columns % tile_info.width);
+  tile_info.y=0;
+  if ((image->rows % tile_info.height) != 0)
+    tile_info.y=(ssize_t) tile_info.height-(image->rows % tile_info.height);
   clahe_info.width=image->columns+tile_info.x;
   clahe_info.height=image->rows+tile_info.y;
   clahe_info.x=(ssize_t) clahe_info.width/tile_info.width;