Minor cleanup

src/ImageSharp/ImageFrame{TPixel}.cs

@@ -144,7 +144,7 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
     }
 
     /// <inheritdoc/>
-    public Buffer2D<TPixel> PixelBuffer { get; private set; }
+    public Buffer2D<TPixel> PixelBuffer { get; }
 
     /// <summary>
     /// Gets or sets the pixel at the specified position.
@@ -309,6 +309,7 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
     /// Copies the pixels to a <see cref="Buffer2D{TPixel}"/> of the same size.
     /// </summary>
     /// <param name="target">The target pixel buffer accessor.</param>
+    /// <exception cref="ArgumentException">ImageFrame{TPixel}.CopyTo(): target must be of the same size!</exception>
     internal void CopyTo(Buffer2D<TPixel> target)
     {
         if (this.Size() != target.Size())
@@ -445,14 +446,12 @@ public sealed class ImageFrame<TPixel> : ImageFrame, IPixelSource<TPixel>
     }
 
     [MethodImpl(InliningOptions.ColdPath)]
-    private static void ThrowArgumentOutOfRangeException(string paramName)
-    {
-        throw new ArgumentOutOfRangeException(paramName);
-    }
+    private static void ThrowArgumentOutOfRangeException(string paramName) => throw new ArgumentOutOfRangeException(paramName);
 
     /// <summary>
     /// A <see langword="struct"/> implementing the clone logic for <see cref="ImageFrame{TPixel}"/>.
     /// </summary>
+    /// <typeparam name="TPixel2">The type of the target pixel format.</typeparam>
     private readonly struct RowIntervalOperation<TPixel2> : IRowIntervalOperation
         where TPixel2 : unmanaged, IPixel<TPixel2>
     {

src/ImageSharp/IndexedImageFrame{TPixel}.cs

@@ -17,8 +17,8 @@ namespace SixLabors.ImageSharp;
 public sealed class IndexedImageFrame<TPixel> : IPixelSource, IDisposable
     where TPixel : unmanaged, IPixel<TPixel>
 {
-    private Buffer2D<byte> pixelBuffer;
-    private IMemoryOwner<TPixel> paletteOwner;
+    private readonly Buffer2D<byte> pixelBuffer;
+    private readonly IMemoryOwner<TPixel> paletteOwner;
     private bool isDisposed;
 
     /// <summary>

src/ImageSharp/Processing/Extensions/ProcessingExtensions.cs

@@ -134,7 +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>
@@ -149,7 +149,7 @@ 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));
@@ -158,7 +158,7 @@ public static partial class ProcessingExtensions
 
         ProcessingVisitor visitor = new(configuration, operation, false);
         source.AcceptVisitor(visitor);
-        return visitor.ResultImage;
+        return visitor.GetResultImage();
     }
 
     /// <summary>
@@ -274,6 +274,8 @@ public static partial class ProcessingExtensions
 
         private readonly bool mutate;
 
+        private Image? resultImage;
+
         public ProcessingVisitor(Configuration configuration, Action<IImageProcessingContext> operation, bool mutate)
         {
             this.configuration = configuration;
@@ -281,7 +283,7 @@ public static partial class ProcessingExtensions
             this.mutate = mutate;
         }
 
-        public Image? ResultImage { get; private set; }
+        public Image GetResultImage() => this.resultImage!;
 
         public void Visit<TPixel>(Image<TPixel> image)
             where TPixel : unmanaged, IPixel<TPixel>
@@ -290,7 +292,7 @@ public static partial class ProcessingExtensions
                 this.configuration.ImageOperationsProvider.CreateImageProcessingContext(this.configuration, image, this.mutate);
 
             this.operation(operationsRunner);
-            this.ResultImage = operationsRunner.GetResultImage();
+            this.resultImage = operationsRunner.GetResultImage();
         }
     }
 }

src/ImageSharp/Processing/ProjectiveTransformBuilder.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Processing;
 /// </summary>
 public class ProjectiveTransformBuilder
 {
-    private readonly List<Func<Size, Matrix4x4>> matrixFactories = new List<Func<Size, Matrix4x4>>();
+    private readonly List<Func<Size, Matrix4x4>> matrixFactories = new();
 
     /// <summary>
     /// Prepends a matrix that performs a tapering projective transform.
@@ -313,7 +313,7 @@ public class ProjectiveTransformBuilder
         Guard.MustBeGreaterThan(sourceRectangle.Height, 0, nameof(sourceRectangle));
 
         // Translate the origin matrix to cater for source rectangle offsets.
-        var matrix = Matrix4x4.CreateTranslation(new Vector3(-sourceRectangle.Location, 0));
+        Matrix4x4 matrix = Matrix4x4.CreateTranslation(new Vector3(-sourceRectangle.Location, 0));
 
         Size size = sourceRectangle.Size;