Add La16 and La32 IPixel formats.

src/ImageSharp/Advanced/AotCompilerTools.cs

@@ -40,16 +40,18 @@ static AotCompilerTools()
         /// </summary>
         private static void SeedEverything()
         {
-            Seed<Alpha8>();
+            Seed<A8>();
             Seed<Argb32>();
             Seed<Bgr24>();
             Seed<Bgr565>();
             Seed<Bgra32>();
             Seed<Bgra4444>();
             Seed<Bgra5551>();
             Seed<Byte4>();
-            Seed<Gray16>();
-            Seed<Gray8>();
+            Seed<L16>();
+            Seed<L8>();
+            Seed<La16>();
+            Seed<La32>();
             Seed<HalfSingle>();
             Seed<HalfVector2>();
             Seed<HalfVector4>();

src/ImageSharp/Common/Helpers/ImageMaths.cs

@@ -38,7 +38,7 @@ public static int GetBT709Luminance(ref Vector4 vector, int luminanceLevels)
         /// <returns>The <see cref="byte"/>.</returns>
         [MethodImpl(InliningOptions.ShortMethod)]
         public static byte Get8BitBT709Luminance(byte r, byte g, byte b) =>
-            (byte)((r * .2126F) + (g * .7152F) + (b * .0722F) + 0.5f);
+            (byte)((r * .2126F) + (g * .7152F) + (b * .0722F) + 0.5F);
 
         /// <summary>
         /// Gets the luminance from the rgb components using the formula as specified by ITU-R Recommendation BT.709.
@@ -49,7 +49,7 @@ public static byte Get8BitBT709Luminance(byte r, byte g, byte b) =>
         /// <returns>The <see cref="ushort"/>.</returns>
         [MethodImpl(InliningOptions.ShortMethod)]
         public static ushort Get16BitBT709Luminance(ushort r, ushort g, ushort b) =>
-            (ushort)((r * .2126F) + (g * .7152F) + (b * .0722F));
+            (ushort)((r * .2126F) + (g * .7152F) + (b * .0722F) + 0.5F);
 
         /// <summary>
         /// Gets the luminance from the rgb components using the formula as specified by ITU-R Recommendation BT.709.
@@ -60,7 +60,7 @@ public static ushort Get16BitBT709Luminance(ushort r, ushort g, ushort b) =>
         /// <returns>The <see cref="ushort"/>.</returns>
         [MethodImpl(InliningOptions.ShortMethod)]
         public static ushort Get16BitBT709Luminance(float r, float g, float b) =>
-            (ushort)((r * .2126F) + (g * .7152F) + (b * .0722F));
+            (ushort)((r * .2126F) + (g * .7152F) + (b * .0722F) + 0.5F);
 
         /// <summary>
         /// Scales a value from a 16 bit <see cref="ushort"/> to it's 8 bit <see cref="byte"/> equivalent.

src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs

@@ -1321,7 +1321,7 @@ private void ReadInfoHeader()
             this.metadata = meta;
 
             short bitsPerPixel = this.infoHeader.BitsPerPixel;
-            this.bmpMetadata = this.metadata.GetFormatMetadata(BmpFormat.Instance);
+            this.bmpMetadata = this.metadata.GetBmpMetadata();
             this.bmpMetadata.InfoHeaderType = infoHeaderType;
 
             // We can only encode at these bit rates so far (1 bit and 4 bit are still missing).

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -105,7 +105,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream)
 
             this.configuration = image.GetConfiguration();
             ImageMetadata metadata = image.Metadata;
-            BmpMetadata bmpMetadata = metadata.GetFormatMetadata(BmpFormat.Instance);
+            BmpMetadata bmpMetadata = metadata.GetBmpMetadata();
             this.bitsPerPixel = this.bitsPerPixel ?? bmpMetadata.BitsPerPixel;
 
             short bpp = (short)this.bitsPerPixel;
@@ -315,11 +315,11 @@ private void Write16Bit<TPixel>(Stream stream, Buffer2D<TPixel> pixels)
         private void Write8Bit<TPixel>(Stream stream, ImageFrame<TPixel> image)
             where TPixel : struct, IPixel<TPixel>
         {
-            bool isGray8 = typeof(TPixel) == typeof(Gray8);
+            bool isL8 = typeof(TPixel) == typeof(L8);
             using (IMemoryOwner<byte> colorPaletteBuffer = this.memoryAllocator.AllocateManagedByteBuffer(ColorPaletteSize8Bit, AllocationOptions.Clean))
             {
                 Span<byte> colorPalette = colorPaletteBuffer.GetSpan();
-                if (isGray8)
+                if (isL8)
                 {
                     this.Write8BitGray(stream, image, colorPalette);
                 }

src/ImageSharp/Formats/Bmp/MetadataExtensions.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Bmp;
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// Extension methods for the <see cref="ImageMetadata"/> type.
+    /// </summary>
+    public static partial class MetadataExtensions
+    {
+        /// <summary>
+        /// Gets the bmp format specific metadata for the image.
+        /// </summary>
+        /// <param name="metadata">The metadata this method extends.</param>
+        /// <returns>The <see cref="BmpMetadata"/>.</returns>
+        public static BmpMetadata GetBmpMetadata(this ImageMetadata metadata) => metadata.GetFormatMetadata(BmpFormat.Instance);
+    }
+}

src/ImageSharp/Formats/Gif/GifDecoderCore.cs

@@ -553,7 +553,7 @@ private void RestoreToBackground<TPixel>(ImageFrame<TPixel> frame)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private void SetFrameMetadata(ImageFrameMetadata meta)
         {
-            GifFrameMetadata gifMeta = meta.GetFormatMetadata(GifFormat.Instance);
+            GifFrameMetadata gifMeta = meta.GetGifMetadata();
             if (this.graphicsControlExtension.DelayTime > 0)
             {
                 gifMeta.FrameDelay = this.graphicsControlExtension.DelayTime;
@@ -615,7 +615,7 @@ private void ReadLogicalScreenDescriptorAndGlobalColorTable(Stream stream)
             }
 
             this.metadata = meta;
-            this.gifMetadata = meta.GetFormatMetadata(GifFormat.Instance);
+            this.gifMetadata = meta.GetGifMetadata();
             this.gifMetadata.ColorTableMode = this.logicalScreenDescriptor.GlobalColorTableFlag
             ? GifColorTableMode.Global
             : GifColorTableMode.Local;

src/ImageSharp/Formats/Gif/GifEncoderCore.cs

@@ -78,7 +78,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream)
             this.configuration = image.GetConfiguration();
 
             ImageMetadata metadata = image.Metadata;
-            GifMetadata gifMetadata = metadata.GetFormatMetadata(GifFormat.Instance);
+            GifMetadata gifMetadata = metadata.GetGifMetadata();
             this.colorTableMode = this.colorTableMode ?? gifMetadata.ColorTableMode;
             bool useGlobalTable = this.colorTableMode == GifColorTableMode.Global;
 
@@ -136,7 +136,7 @@ private void EncodeGlobal<TPixel>(Image<TPixel> image, IQuantizedFrame<TPixel> q
             {
                 ImageFrame<TPixel> frame = image.Frames[i];
                 ImageFrameMetadata metadata = frame.Metadata;
-                GifFrameMetadata frameMetadata = metadata.GetFormatMetadata(GifFormat.Instance);
+                GifFrameMetadata frameMetadata = metadata.GetGifMetadata();
                 this.WriteGraphicalControlExtension(frameMetadata, transparencyIndex, stream);
                 this.WriteImageDescriptor(frame, false, stream);
 
@@ -166,7 +166,7 @@ private void EncodeLocal<TPixel>(Image<TPixel> image, IQuantizedFrame<TPixel> qu
             foreach (ImageFrame<TPixel> frame in image.Frames)
             {
                 ImageFrameMetadata metadata = frame.Metadata;
-                GifFrameMetadata frameMetadata = metadata.GetFormatMetadata(GifFormat.Instance);
+                GifFrameMetadata frameMetadata = metadata.GetGifMetadata();
                 if (quantized is null)
                 {
                     // Allow each frame to be encoded at whatever color depth the frame designates if set.

src/ImageSharp/Formats/Gif/MetadataExtensions.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Gif;
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// Extension methods for the <see cref="ImageMetadata"/> type.
+    /// </summary>
+    public static partial class MetadataExtensions
+    {
+        /// <summary>
+        /// Gets the gif format specific metadata for the image.
+        /// </summary>
+        /// <param name="metadata">The metadata this method extends.</param>
+        /// <returns>The <see cref="GifMetadata"/>.</returns>
+        public static GifMetadata GetGifMetadata(this ImageMetadata metadata) => metadata.GetFormatMetadata(GifFormat.Instance);
+
+        /// <summary>
+        /// Gets the gif format specific metadata for the image frame.
+        /// </summary>
+        /// <param name="metadata">The metadata this method extends.</param>
+        /// <returns>The <see cref="GifFrameMetadata"/>.</returns>
+        public static GifFrameMetadata GetGifMetadata(this ImageFrameMetadata metadata) => metadata.GetFormatMetadata(GifFormat.Instance);
+    }
+}

src/ImageSharp/Formats/IImageDecoder.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System.IO;
@@ -17,17 +17,16 @@ public interface IImageDecoder
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="configuration">The configuration for the image.</param>
         /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
-        /// <returns>The decoded image of a given pixel type.</returns>
+        /// <returns>The <see cref="Image{TPixel}"/>.</returns>
         Image<TPixel> Decode<TPixel>(Configuration configuration, Stream stream)
             where TPixel : struct, IPixel<TPixel>;
 
         /// <summary>
         /// Decodes the image from the specified stream to an <see cref="Image"/>.
-        /// The decoder is free to choose the pixel type.
         /// </summary>
         /// <param name="configuration">The configuration for the image.</param>
         /// <param name="stream">The <see cref="Stream"/> containing image data.</param>
-        /// <returns>The decoded image of a pixel type chosen by the decoder.</returns>
+        /// <returns>The <see cref="Image"/>.</returns>
         Image Decode(Configuration configuration, Stream stream);
     }
 }

src/ImageSharp/Formats/Jpeg/JpegDecoder.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System.IO;
@@ -28,6 +28,10 @@ public Image<TPixel> Decode<TPixel>(Configuration configuration, Stream stream)
             }
         }
 
+        /// <inheritdoc />
+        public Image Decode(Configuration configuration, Stream stream)
+            => this.Decode<Rgba32>(configuration, stream);
+
         /// <inheritdoc/>
         public IImageInfo Identify(Configuration configuration, Stream stream)
         {
@@ -38,8 +42,5 @@ public IImageInfo Identify(Configuration configuration, Stream stream)
                 return decoder.Identify(stream);
             }
         }
-
-        /// <inheritdoc />
-        public Image Decode(Configuration configuration, Stream stream) => this.Decode<Rgba32>(configuration, stream);
     }
-}
+}

src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs

@@ -649,48 +649,51 @@ private void ProcessDefineQuantizationTablesMarker(int remaining)
                 switch (quantizationTableSpec >> 4)
                 {
                     case 0:
+                    {
+                        // 8 bit values
+                        if (remaining < 64)
                         {
-                            // 8 bit values
-                            if (remaining < 64)
-                            {
-                                done = true;
-                                break;
-                            }
+                            done = true;
+                            break;
+                        }
 
-                            this.InputStream.Read(this.temp, 0, 64);
-                            remaining -= 64;
+                        this.InputStream.Read(this.temp, 0, 64);
+                        remaining -= 64;
 
-                            ref Block8x8F table = ref this.QuantizationTables[tableIndex];
-                            for (int j = 0; j < 64; j++)
-                            {
-                                table[j] = this.temp[j];
-                            }
+                        ref Block8x8F table = ref this.QuantizationTables[tableIndex];
+                        for (int j = 0; j < 64; j++)
+                        {
+                            table[j] = this.temp[j];
                         }
+                    }
 
-                        break;
+                    break;
                     case 1:
+                    {
+                        // 16 bit values
+                        if (remaining < 128)
                         {
-                            // 16 bit values
-                            if (remaining < 128)
-                            {
-                                done = true;
-                                break;
-                            }
+                            done = true;
+                            break;
+                        }
 
-                            this.InputStream.Read(this.temp, 0, 128);
-                            remaining -= 128;
+                        this.InputStream.Read(this.temp, 0, 128);
+                        remaining -= 128;
 
-                            ref Block8x8F table = ref this.QuantizationTables[tableIndex];
-                            for (int j = 0; j < 64; j++)
-                            {
-                                table[j] = (this.temp[2 * j] << 8) | this.temp[(2 * j) + 1];
-                            }
+                        ref Block8x8F table = ref this.QuantizationTables[tableIndex];
+                        for (int j = 0; j < 64; j++)
+                        {
+                            table[j] = (this.temp[2 * j] << 8) | this.temp[(2 * j) + 1];
                         }
+                    }
+
+                    break;
 
-                        break;
                     default:
+                    {
                         JpegThrowHelper.ThrowBadQuantizationTable();
                         break;
+                    }
                 }
 
                 if (done)

src/ImageSharp/Formats/Jpeg/JpegEncoderCore.cs

@@ -206,7 +206,7 @@ public void Encode<TPixel>(Image<TPixel> image, Stream stream)
             ImageMetadata metadata = image.Metadata;
 
             // System.Drawing produces identical output for jpegs with a quality parameter of 0 and 1.
-            int qlty = (this.quality ?? metadata.GetFormatMetadata(JpegFormat.Instance).Quality).Clamp(1, 100);
+            int qlty = (this.quality ?? metadata.GetJpegMetadata().Quality).Clamp(1, 100);
             this.subsample = this.subsample ?? (qlty >= 91 ? JpegSubsample.Ratio444 : JpegSubsample.Ratio420);
 
             // Convert from a quality rating to a scaling factor.

src/ImageSharp/Formats/Jpeg/MetadataExtensions.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Jpeg;
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// Extension methods for the <see cref="ImageMetadata"/> type.
+    /// </summary>
+    public static partial class MetadataExtensions
+    {
+        /// <summary>
+        /// Gets the jpeg format specific metadata for the image.
+        /// </summary>
+        /// <param name="metadata">The metadata this method extends.</param>
+        /// <returns>The <see cref="JpegMetadata"/>.</returns>
+        public static JpegMetadata GetJpegMetadata(this ImageMetadata metadata) => metadata.GetFormatMetadata(JpegFormat.Instance);
+    }
+}

src/ImageSharp/Formats/Png/MetadataExtensions.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.Metadata;
+
+namespace SixLabors.ImageSharp
+{
+    /// <summary>
+    /// Extension methods for the <see cref="ImageMetadata"/> type.
+    /// </summary>
+    public static partial class MetadataExtensions
+    {
+        /// <summary>
+        /// Gets the png format specific metadata for the image.
+        /// </summary>
+        /// <param name="metadata">The metadata this method extends.</param>
+        /// <returns>The <see cref="PngMetadata"/>.</returns>
+        public static PngMetadata GetPngMetadata(this ImageMetadata metadata) => metadata.GetFormatMetadata(PngFormat.Instance);
+    }
+}