From 6cdc7493d57ddb3bc82bdc28523d961ad138600e Mon Sep 17 00:00:00 2001
From: Sean Owen <srowen@gmail.com>
Date: Fri, 10 Jun 2016 13:58:51 +0100
Subject: [PATCH] Closes Issue #607 : guard against very narrow images which
 would otherwise cause an exception

---
 .../common/GlobalHistogramBinarizer.java      | 31 ++++++++++++-------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/core/src/main/java/com/google/zxing/common/GlobalHistogramBinarizer.java b/core/src/main/java/com/google/zxing/common/GlobalHistogramBinarizer.java
index b4c0edbd8..3f737587d 100644
--- a/core/src/main/java/com/google/zxing/common/GlobalHistogramBinarizer.java
+++ b/core/src/main/java/com/google/zxing/common/GlobalHistogramBinarizer.java
@@ -62,22 +62,29 @@ public class GlobalHistogramBinarizer extends Binarizer {
     byte[] localLuminances = source.getRow(y, luminances);
     int[] localBuckets = buckets;
     for (int x = 0; x < width; x++) {
-      int pixel = localLuminances[x] & 0xff;
-      localBuckets[pixel >> LUMINANCE_SHIFT]++;
+      localBuckets[(localLuminances[x] & 0xff) >> LUMINANCE_SHIFT]++;
     }
     int blackPoint = estimateBlackPoint(localBuckets);
 
-    int left = localLuminances[0] & 0xff;
-    int center = localLuminances[1] & 0xff;
-    for (int x = 1; x < width - 1; x++) {
-      int right = localLuminances[x + 1] & 0xff;
-      // A simple -1 4 -1 box filter with a weight of 2.
-      int luminance = ((center * 4) - left - right) / 2;
-      if (luminance < blackPoint) {
-        row.set(x);
+    if (width < 3) {
+      // Special case for very small images
+      for (int x = 0; x < width; x++) {
+        if ((localLuminances[x] & 0xff) < blackPoint) {
+          row.set(x);
+        }
+      }
+    } else {
+      int left = localLuminances[0] & 0xff;
+      int center = localLuminances[1] & 0xff;
+      for (int x = 1; x < width - 1; x++) {
+        int right = localLuminances[x + 1] & 0xff;
+        // A simple -1 4 -1 box filter with a weight of 2.
+        if (((center * 4) - left - right) / 2 < blackPoint) {
+          row.set(x);
+        }
+        left = center;
+        center = right;
       }
-      left = center;
-      center = right;
     }
     return row;
   }