From 8238c8fd6fd3414abae22adfcccda8537b45bbe5 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Wed, 4 Aug 2021 00:25:22 +1000
Subject: [PATCH] Add additional checks

---
 src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs   | 2 ++
 src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs b/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs
index 35347933d..09ce4ebd9 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/ErrorDither.cs
@@ -27,6 +27,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         [MethodImpl(InliningOptions.ShortMethod)]
         public ErrorDither(in DenseMatrix<float> matrix, int offset)
         {
+            Guard.MustBeGreaterThan(offset, 0, nameof(offset));
+
             this.matrix = matrix;
             this.offset = offset;
         }
diff --git a/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs b/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs
index b8eb0e390..2b5c7fc6b 100644
--- a/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs
+++ b/src/ImageSharp/Processing/Processors/Dithering/OrderedDither.cs
@@ -24,6 +24,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Dithering
         [MethodImpl(InliningOptions.ShortMethod)]
         public OrderedDither(uint length)
         {
+            Guard.MustBeGreaterThan(length, 0, nameof(length));
+
             DenseMatrix<uint> ditherMatrix = OrderedDitherFactory.CreateDitherMatrix(length);
 
             // Create a new matrix to run against, that pre-thresholds the values.