Use PixelOperations for buffer copying.

src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs

@@ -21,11 +21,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
 internal class SpectralConverter<TPixel> : SpectralConverter, IDisposable
     where TPixel : unmanaged, IPixel<TPixel>
 {
-    /// <summary>
-    /// <see cref="Configuration"/> instance associated with current
-    /// decoding routine.
-    /// </summary>
-    private readonly Configuration configuration;
 
     private JpegFrame frame;
 
@@ -81,11 +76,15 @@ internal class SpectralConverter<TPixel> : SpectralConverter, IDisposable
     /// <param name="targetSize">Optional target size for decoded image.</param>
     public SpectralConverter(Configuration configuration, Size? targetSize = null)
     {
-        this.configuration = configuration;
-
+        this.Configuration = configuration;
         this.targetSize = targetSize;
     }
 
+    /// <summary>
+    /// Gets the configuration instance associated with current decoding routine.
+    /// </summary>
+    public Configuration Configuration { get; }
+
     /// <summary>
     /// Gets converted pixel buffer.
     /// </summary>
@@ -177,7 +176,7 @@ internal class SpectralConverter<TPixel> : SpectralConverter, IDisposable
     {
         DebugGuard.IsTrue(this.colorConverter == null, "SpectralConverter.PrepareForDecoding() must be called once.");
 
-        MemoryAllocator allocator = this.configuration.MemoryAllocator;
+        MemoryAllocator allocator = this.Configuration.MemoryAllocator;
 
         // color converter from RGB to TPixel
         JpegColorConverterBase converter = this.GetColorConverter(this.frame, this.jpegData);
@@ -196,7 +195,7 @@ internal class SpectralConverter<TPixel> : SpectralConverter, IDisposable
         this.pixelBuffer = allocator.Allocate2D<TPixel>(
             pixelSize.Width,
             pixelSize.Height,
-            this.configuration.PreferContiguousImageBuffers);
+            this.Configuration.PreferContiguousImageBuffers);
         this.paddedProxyPixelRow = allocator.Allocate<TPixel>(pixelSize.Width + 3);
 
         // component processors from spectral to RGB
@@ -225,7 +224,7 @@ internal class SpectralConverter<TPixel> : SpectralConverter, IDisposable
 
     protected ComponentProcessor[] CreateComponentProcessors(JpegFrame frame, IRawJpegData jpegData, int blockPixelSize, Size processorBufferSize)
     {
-        MemoryAllocator allocator = this.configuration.MemoryAllocator;
+        MemoryAllocator allocator = this.Configuration.MemoryAllocator;
         var componentProcessors = new ComponentProcessor[frame.Components.Length];
         for (int i = 0; i < componentProcessors.Length; i++)
         {

src/ImageSharp/Formats/Tiff/Compression/Decompressors/JpegCompressionUtils.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -9,27 +9,25 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors;
 
 internal static class JpegCompressionUtils
 {
-    public static void CopyImageBytesToBuffer(Span<byte> buffer, Buffer2D<Rgb24> pixelBuffer)
+    public static void CopyImageBytesToBuffer(Configuration configuration, Span<byte> buffer, Buffer2D<Rgb24> pixelBuffer)
     {
         int offset = 0;
         for (int y = 0; y < pixelBuffer.Height; y++)
         {
             Span<Rgb24> pixelRowSpan = pixelBuffer.DangerousGetRowSpan(y);
-            Span<byte> rgbBytes = MemoryMarshal.AsBytes(pixelRowSpan);
-            rgbBytes.CopyTo(buffer[offset..]);
-            offset += rgbBytes.Length;
+            PixelOperations<Rgb24>.Instance.ToRgb24Bytes(configuration, pixelRowSpan, buffer[offset..], pixelRowSpan.Length);
+            offset += Unsafe.SizeOf<Rgb24>() * pixelRowSpan.Length;
         }
     }
 
-    public static void CopyImageBytesToBuffer(Span<byte> buffer, Buffer2D<L8> pixelBuffer)
+    public static void CopyImageBytesToBuffer(Configuration configuration, Span<byte> buffer, Buffer2D<L8> pixelBuffer)
     {
         int offset = 0;
         for (int y = 0; y < pixelBuffer.Height; y++)
         {
             Span<L8> pixelRowSpan = pixelBuffer.DangerousGetRowSpan(y);
-            Span<byte> rgbBytes = MemoryMarshal.AsBytes(pixelRowSpan);
-            rgbBytes.CopyTo(buffer[offset..]);
-            offset += rgbBytes.Length;
+            PixelOperations<L8>.Instance.ToL8Bytes(configuration, pixelRowSpan, buffer[offset..], pixelRowSpan.Length);
+            offset += Unsafe.SizeOf<L8>() * pixelRowSpan.Length;
         }
     }
 }

src/ImageSharp/Formats/Tiff/Compression/Decompressors/JpegTiffCompression.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
 using SixLabors.ImageSharp.Formats.Tiff.Constants;
@@ -73,8 +74,8 @@ internal sealed class JpegTiffCompression : TiffBaseDecompressor
         }
         else
         {
-            using Image<Rgb24> image = Image.Load<Rgb24>(stream);
-            JpegCompressionUtils.CopyImageBytesToBuffer(buffer, image.Frames.RootFrame.PixelBuffer);
+            using Image<Rgb24> image = Image.Load<Rgb24>(this.options.GeneralOptions, stream);
+            JpegCompressionUtils.CopyImageBytesToBuffer(this.options.GeneralOptions.Configuration, buffer, image.Frames.RootFrame.PixelBuffer);
         }
     }
 
@@ -94,7 +95,7 @@ internal sealed class JpegTiffCompression : TiffBaseDecompressor
                 jpegDecoder.ParseStream(stream, spectralConverterGray, cancellationToken);
 
                 using Buffer2D<L8> decompressedBuffer = spectralConverterGray.GetPixelBuffer(cancellationToken);
-                JpegCompressionUtils.CopyImageBytesToBuffer(buffer, decompressedBuffer);
+                JpegCompressionUtils.CopyImageBytesToBuffer(spectralConverterGray.Configuration, buffer, decompressedBuffer);
                 break;
             }
 
@@ -108,7 +109,7 @@ internal sealed class JpegTiffCompression : TiffBaseDecompressor
                 jpegDecoder.ParseStream(stream, spectralConverter, cancellationToken);
 
                 using Buffer2D<Rgb24> decompressedBuffer = spectralConverter.GetPixelBuffer(cancellationToken);
-                JpegCompressionUtils.CopyImageBytesToBuffer(buffer, decompressedBuffer);
+                JpegCompressionUtils.CopyImageBytesToBuffer(spectralConverter.Configuration, buffer, decompressedBuffer);
                 break;
             }
 

src/ImageSharp/Formats/Tiff/Compression/Decompressors/OldJpegTiffCompression.cs

@@ -58,7 +58,7 @@ internal sealed class OldJpegTiffCompression : TiffBaseDecompressor
                 jpegDecoder.ParseStream(stream, spectralConverterGray, cancellationToken);
 
                 using Buffer2D<L8> decompressedBuffer = spectralConverterGray.GetPixelBuffer(cancellationToken);
-                JpegCompressionUtils.CopyImageBytesToBuffer(buffer, decompressedBuffer);
+                JpegCompressionUtils.CopyImageBytesToBuffer(spectralConverterGray.Configuration, buffer, decompressedBuffer);
                 break;
             }
 
@@ -70,7 +70,7 @@ internal sealed class OldJpegTiffCompression : TiffBaseDecompressor
                 jpegDecoder.ParseStream(stream, spectralConverter, cancellationToken);
 
                 using Buffer2D<Rgb24> decompressedBuffer = spectralConverter.GetPixelBuffer(cancellationToken);
-                JpegCompressionUtils.CopyImageBytesToBuffer(buffer, decompressedBuffer);
+                JpegCompressionUtils.CopyImageBytesToBuffer(spectralConverter.Configuration, buffer, decompressedBuffer);
                 break;
             }