diff --git a/src/ImageSharp/Common/Helpers/Guard.cs b/src/ImageSharp/Common/Helpers/Guard.cs
index 95211ccda8..a485bf9b36 100644
--- a/src/ImageSharp/Common/Helpers/Guard.cs
+++ b/src/ImageSharp/Common/Helpers/Guard.cs
@@ -1,9 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Processing.Processors.Transforms;
 
 namespace SixLabors;
 
@@ -17,13 +17,14 @@ internal static partial class Guard
     /// <typeparam name="TValue">The type of the value.</typeparam>
     /// <exception cref="ArgumentException"><paramref name="value"/> is not a value type.</exception>
     [MethodImpl(InliningOptions.ShortMethod)]
-    public static void MustBeValueType<TValue>(TValue value, string parameterName)
+    public static void SamplerMustBeValueType<TValue>(TValue value, [CallerArgumentExpression("value")] string? parameterName = null)
+        where TValue : IResampler
     {
         if (value.GetType().IsValueType)
         {
             return;
         }
 
-        ThrowHelper.ThrowArgumentException("Type must be a struct.", parameterName);
+        ThrowHelper.ThrowArgumentException("Type must be a struct.", parameterName!);
     }
 }
diff --git a/src/ImageSharp/ImageExtensions.cs b/src/ImageSharp/ImageExtensions.cs
index 04930a2689..cf970b3166 100644
--- a/src/ImageSharp/ImageExtensions.cs
+++ b/src/ImageSharp/ImageExtensions.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Globalization;
 using System.Text;
@@ -180,6 +179,6 @@ public static partial class ImageExtensions
 
         // Always available.
         stream.TryGetBuffer(out ArraySegment<byte> buffer);
-        return $"data:{format.DefaultMimeType};base64,{Convert.ToBase64String(buffer.Array, 0, (int)stream.Length)}";
+        return $"data:{format.DefaultMimeType};base64,{Convert.ToBase64String(buffer.Array ?? Array.Empty<byte>(), 0, (int)stream.Length)}";
     }
 }
diff --git a/src/ImageSharp/ImageFrame{TPixel}.cs b/src/ImageSharp/ImageFrame{TPixel}.cs
index fb4ee6ae5f..becd69a0eb 100644
--- a/src/ImageSharp/ImageFrame{TPixel}.cs
+++ b/src/ImageSharp/ImageFrame{TPixel}.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -183,7 +182,7 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
 
         try
         {
-            var accessor = new PixelAccessor<TPixel>(this.PixelBuffer);
+            PixelAccessor<TPixel> accessor = new(this.PixelBuffer);
             processPixels(accessor);
         }
         finally
@@ -211,8 +210,8 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
 
         try
         {
-            var accessor1 = new PixelAccessor<TPixel>(this.PixelBuffer);
-            var accessor2 = new PixelAccessor<TPixel2>(frame2.PixelBuffer);
+            PixelAccessor<TPixel> accessor1 = new(this.PixelBuffer);
+            PixelAccessor<TPixel2> accessor2 = new(frame2.PixelBuffer);
             processPixels(accessor1, accessor2);
         }
         finally
@@ -247,9 +246,9 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
 
         try
         {
-            var accessor1 = new PixelAccessor<TPixel>(this.PixelBuffer);
-            var accessor2 = new PixelAccessor<TPixel2>(frame2.PixelBuffer);
-            var accessor3 = new PixelAccessor<TPixel3>(frame3.PixelBuffer);
+            PixelAccessor<TPixel> accessor1 = new(this.PixelBuffer);
+            PixelAccessor<TPixel2> accessor2 = new(frame2.PixelBuffer);
+            PixelAccessor<TPixel3> accessor3 = new(frame3.PixelBuffer);
             processPixels(accessor1, accessor2, accessor3);
         }
         finally
@@ -342,8 +341,7 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
 
         if (disposing)
         {
-            this.PixelBuffer?.Dispose();
-            this.PixelBuffer = null;
+            this.PixelBuffer.Dispose();
         }
 
         this.isDisposed = true;
@@ -379,14 +377,14 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
     /// </summary>
     /// <param name="configuration">The configuration providing initialization code which allows extending the library.</param>
     /// <returns>The <see cref="ImageFrame{TPixel}"/></returns>
-    internal ImageFrame<TPixel> Clone(Configuration configuration) => new ImageFrame<TPixel>(configuration, this);
+    internal ImageFrame<TPixel> Clone(Configuration configuration) => new(configuration, this);
 
     /// <summary>
     /// Returns a copy of the image frame in the given pixel format.
     /// </summary>
     /// <typeparam name="TPixel2">The pixel format.</typeparam>
     /// <returns>The <see cref="ImageFrame{TPixel2}"/></returns>
-    internal ImageFrame<TPixel2> CloneAs<TPixel2>()
+    internal ImageFrame<TPixel2>? CloneAs<TPixel2>()
         where TPixel2 : unmanaged, IPixel<TPixel2> => this.CloneAs<TPixel2>(this.GetConfiguration());
 
     /// <summary>
@@ -400,11 +398,11 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
     {
         if (typeof(TPixel2) == typeof(TPixel))
         {
-            return this.Clone(configuration) as ImageFrame<TPixel2>;
+            return (this.Clone(configuration) as ImageFrame<TPixel2>)!;
         }
 
-        var target = new ImageFrame<TPixel2>(configuration, this.Width, this.Height, this.Metadata.DeepClone());
-        var operation = new RowIntervalOperation<TPixel2>(this.PixelBuffer, target.PixelBuffer, configuration);
+        ImageFrame<TPixel2> target = new(configuration, this.Width, this.Height, this.Metadata.DeepClone());
+        RowIntervalOperation<TPixel2> operation = new(this.PixelBuffer, target.PixelBuffer, configuration);
 
         ParallelRowIterator.IterateRowIntervals(
             configuration,
diff --git a/src/ImageSharp/IndexedImageFrame{TPixel}.cs b/src/ImageSharp/IndexedImageFrame{TPixel}.cs
index 741b3219e0..12a78a0239 100644
--- a/src/ImageSharp/IndexedImageFrame{TPixel}.cs
+++ b/src/ImageSharp/IndexedImageFrame{TPixel}.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using System.Runtime.CompilerServices;
@@ -109,8 +108,6 @@ public sealed class IndexedImageFrame<TPixel> : IPixelSource, IDisposable
             this.isDisposed = true;
             this.pixelBuffer.Dispose();
             this.paletteOwner.Dispose();
-            this.pixelBuffer = null;
-            this.paletteOwner = null;
         }
     }
 }
diff --git a/src/ImageSharp/Processing/Extensions/ProcessingExtensions.cs b/src/ImageSharp/Processing/Extensions/ProcessingExtensions.cs
index 575ce293ca..02e688f57f 100644
--- a/src/ImageSharp/Processing/Extensions/ProcessingExtensions.cs
+++ b/src/ImageSharp/Processing/Extensions/ProcessingExtensions.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.PixelFormats;
@@ -135,7 +134,7 @@ public static partial class ProcessingExtensions
     /// <exception cref="ArgumentNullException">The operation is null.</exception>
     /// <exception cref="ObjectDisposedException">The source has been disposed.</exception>
     /// <exception cref="ImageProcessingException">The processing operation failed.</exception>
-    public static Image Clone(this Image source, Action<IImageProcessingContext> operation)
+    public static Image? Clone(this Image source, Action<IImageProcessingContext> operation)
         => Clone(source, source.GetConfiguration(), operation);
 
     /// <summary>
@@ -150,14 +149,14 @@ public static partial class ProcessingExtensions
     /// <exception cref="ObjectDisposedException">The source has been disposed.</exception>
     /// <exception cref="ImageProcessingException">The processing operation failed.</exception>
     /// <returns>The new <see cref="Image"/>.</returns>
-    public static Image Clone(this Image source, Configuration configuration, Action<IImageProcessingContext> operation)
+    public static Image? Clone(this Image source, Configuration configuration, Action<IImageProcessingContext> operation)
     {
         Guard.NotNull(configuration, nameof(configuration));
         Guard.NotNull(source, nameof(source));
         Guard.NotNull(operation, nameof(operation));
         source.EnsureNotDisposed();
 
-        var visitor = new ProcessingVisitor(configuration, operation, false);
+        ProcessingVisitor visitor = new(configuration, operation, false);
         source.AcceptVisitor(visitor);
         return visitor.ResultImage;
     }
@@ -282,7 +281,7 @@ public static partial class ProcessingExtensions
             this.mutate = mutate;
         }
 
-        public Image ResultImage { get; private set; }
+        public Image? ResultImage { get; private set; }
 
         public void Visit<TPixel>(Image<TPixel> image)
             where TPixel : unmanaged, IPixel<TPixel>
diff --git a/src/ImageSharp/Processing/Processors/Transforms/Linear/AffineTransformProcessor.cs b/src/ImageSharp/Processing/Processors/Transforms/Linear/AffineTransformProcessor.cs
index abb8beccdf..4a13e69174 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/Linear/AffineTransformProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/Linear/AffineTransformProcessor.cs
@@ -19,7 +19,7 @@ public class AffineTransformProcessor : CloningImageProcessor
     public AffineTransformProcessor(Matrix3x2 matrix, IResampler sampler, Size targetDimensions)
     {
         Guard.NotNull(sampler, nameof(sampler));
-        Guard.MustBeValueType(sampler, nameof(sampler));
+        Guard.SamplerMustBeValueType(sampler);
 
         if (TransformUtils.IsDegenerate(matrix))
         {
diff --git a/src/ImageSharp/Processing/Processors/Transforms/Linear/ProjectiveTransformProcessor.cs b/src/ImageSharp/Processing/Processors/Transforms/Linear/ProjectiveTransformProcessor.cs
index 9b0b979e69..55e3227fb7 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/Linear/ProjectiveTransformProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/Linear/ProjectiveTransformProcessor.cs
@@ -19,7 +19,7 @@ public sealed class ProjectiveTransformProcessor : CloningImageProcessor
     public ProjectiveTransformProcessor(Matrix4x4 matrix, IResampler sampler, Size targetDimensions)
     {
         Guard.NotNull(sampler, nameof(sampler));
-        Guard.MustBeValueType(sampler, nameof(sampler));
+        Guard.SamplerMustBeValueType(sampler);
 
         if (TransformUtils.IsDegenerate(matrix))
         {
diff --git a/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor.cs b/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor.cs
index b7651c03f3..f056e434ed 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor.cs
@@ -17,7 +17,7 @@ public class ResizeProcessor : CloningImageProcessor
     {
         Guard.NotNull(options, nameof(options));
         Guard.NotNull(options.Sampler, nameof(options.Sampler));
-        Guard.MustBeValueType(options.Sampler, nameof(options.Sampler));
+        Guard.SamplerMustBeValueType(options.Sampler);
 
         (Size size, Rectangle rectangle) = ResizeHelper.CalculateTargetLocationAndBounds(sourceSize, options);