Add support for encoding 16 bit per pixel bitmaps

src/ImageSharp/Formats/Bmp/BmpBitsPerPixel.cs

@@ -8,6 +8,11 @@ namespace SixLabors.ImageSharp.Formats.Bmp
     /// </summary>
     public enum BmpBitsPerPixel : short
     {
+        /// <summary>
+        /// 16 bits per pixel. Each pixel consists of 2 bytes.
+        /// </summary>
+        Pixel16 = 16,
+
         /// <summary>
         /// 24 bits per pixel. Each pixel consists of 3 bytes.
         /// </summary>

src/ImageSharp/Formats/Bmp/BmpDecoderCore.cs

@@ -1022,7 +1022,8 @@ private void ReadInfoHeader()
             this.bmpMetadata.InfoHeaderType = infoHeaderType;
 
             // We can only encode at these bit rates so far.
-            if (bitsPerPixel.Equals((short)BmpBitsPerPixel.Pixel24)
+            if (bitsPerPixel.Equals((short)BmpBitsPerPixel.Pixel16)
+                || bitsPerPixel.Equals((short)BmpBitsPerPixel.Pixel24)
                 || bitsPerPixel.Equals((short)BmpBitsPerPixel.Pixel32))
             {
                 this.bmpMetadata.BitsPerPixel = (BmpBitsPerPixel)bitsPerPixel;

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -194,6 +194,10 @@ private void WriteImage<TPixel>(Stream stream, ImageFrame<TPixel> image)
                 case BmpBitsPerPixel.Pixel24:
                     this.Write24Bit(stream, pixels);
                     break;
+
+                case BmpBitsPerPixel.Pixel16:
+                    this.Write16Bit(stream, pixels);
+                    break;
             }
         }
 
@@ -246,5 +250,31 @@ private void Write24Bit<TPixel>(Stream stream, Buffer2D<TPixel> pixels)
                 }
             }
         }
+
+        /// <summary>
+        /// Writes the 16bit color palette to the stream.
+        /// </summary>
+        /// <typeparam name="TPixel">The type of the pixel.</typeparam>
+        /// <param name="stream">The <see cref="Stream"/> to write to.</param>
+        /// <param name="pixels">The <see cref="Buffer2D{TPixel}"/> containing pixel data.</param>
+        private void Write16Bit<TPixel>(Stream stream, Buffer2D<TPixel> pixels)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (IManagedByteBuffer row = this.AllocateRow(pixels.Width, 2))
+            {
+                for (int y = pixels.Height - 1; y >= 0; y--)
+                {
+                    Span<TPixel> pixelSpan = pixels.GetRowSpan(y);
+
+                    PixelOperations<TPixel>.Instance.ToBgra5551Bytes(
+                        this.configuration,
+                        pixelSpan,
+                        row.GetSpan(),
+                        pixelSpan.Length);
+
+                    stream.Write(row.Array, 0, row.Length());
+                }
+            }
+        }
     }
 }

src/ImageSharp/Formats/Bmp/IBmpEncoderOptions.cs

@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Formats.Bmp
     /// <summary>
     /// Configuration options for use during bmp encoding
     /// </summary>
-    /// <remarks>The encoder can currently only write 24-bit and 32-bit rgb images to streams.</remarks>
+    /// <remarks>The encoder can currently only write 16-bit, 24-bit and 32-bit rgb images to streams.</remarks>
     internal interface IBmpEncoderOptions
     {
         /// <summary>

src/ImageSharp/PixelFormats/IPixel.cs

@@ -61,6 +61,12 @@ public interface IPixel
         /// <param name="source">The <see cref="Argb32"/> value.</param>
         void FromArgb32(Argb32 source);
 
+        /// <summary>
+        /// Initializes the pixel instance from an <see cref="Bgra5551"/> value.
+        /// </summary>
+        /// <param name="source">The <see cref="Bgra5551"/> value.</param>
+        void FromBgra5551(Bgra5551 source);
+
         /// <summary>
         /// Initializes the pixel instance from an <see cref="Bgr24"/> value.
         /// </summary>

src/ImageSharp/PixelFormats/PixelImplementations/Alpha8.cs

@@ -87,6 +87,10 @@ public struct Alpha8 : IPixel<Alpha8>, IPackedVector<byte>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.PackedValue = source.A;
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.PackedValue = byte.MaxValue;

src/ImageSharp/PixelFormats/PixelImplementations/Argb32.cs

@@ -187,6 +187,10 @@ public uint PackedValue
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromArgb32(Argb32 source) => this.PackedValue = source.PackedValue;
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgr24(Bgr24 source)

src/ImageSharp/PixelFormats/PixelImplementations/Bgr24.cs

@@ -109,6 +109,10 @@ public void FromArgb32(Argb32 source)
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgr24(Bgr24 source) => this = source;
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source)

src/ImageSharp/PixelFormats/PixelImplementations/Bgr565.cs

@@ -87,6 +87,10 @@ public void FromVector4(Vector4 vector)
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromArgb32(Argb32 source) => this.FromVector4(source.ToVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromVector4(source.ToVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgr24(Bgr24 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Bgra32.cs

@@ -159,6 +159,10 @@ public void FromBgr24(Bgr24 source)
             this.A = byte.MaxValue;
         }
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this = source;

src/ImageSharp/PixelFormats/PixelImplementations/Bgra4444.cs

@@ -90,6 +90,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromArgb32(Argb32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgr24(Bgr24 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Bgra5551.cs

@@ -87,6 +87,10 @@ public Vector4 ToVector4()
                         (this.PackedValue >> 15) & 0x01);
         }
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this = source;
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromArgb32(Argb32 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Byte4.cs

@@ -111,6 +111,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromRgb24(Rgb24 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromRgba32(Rgba32 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Gray16.cs

@@ -106,6 +106,10 @@ public void FromBgra32(Bgra32 source)
                 ImageMaths.UpscaleFrom8BitTo16Bit(source.B));
         }
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.PackedValue = ImageMaths.UpscaleFrom8BitTo16Bit(source.PackedValue);

src/ImageSharp/PixelFormats/PixelImplementations/Gray8.cs

@@ -97,6 +97,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.PackedValue = ImageMaths.Get8BitBT709Luminance(source.R, source.G, source.B);
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.PackedValue = source.PackedValue;

src/ImageSharp/PixelFormats/PixelImplementations/HalfSingle.cs

@@ -88,6 +88,10 @@ public Vector4 ToScaledVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/HalfVector2.cs

@@ -99,6 +99,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/HalfVector4.cs

@@ -107,6 +107,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/NormalizedByte2.cs

@@ -8,7 +8,7 @@
 namespace SixLabors.ImageSharp.PixelFormats
 {
     /// <summary>
-    /// Packed packed pixel type containing two 8-bit signed normalized values, ranging from −1 to 1.
+    /// Packed pixel type containing two 8-bit signed normalized values, ranging from −1 to 1.
     /// <para>
     /// Ranges from [-1, -1, 0, 1] to [1, 1, 0, 1] in vector form.
     /// </para>
@@ -107,10 +107,11 @@ public void FromVector4(Vector4 vector)
 
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
-        public void ToRgba32(ref Rgba32 dest)
-        {
-            dest.FromScaledVector4(this.ToScaledVector4());
-        }
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void ToRgba32(ref Rgba32 dest) => dest.FromScaledVector4(this.ToScaledVector4());
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]

src/ImageSharp/PixelFormats/PixelImplementations/NormalizedByte4.cs

@@ -110,6 +110,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/NormalizedShort2.cs

@@ -105,6 +105,10 @@ public void FromVector4(Vector4 vector)
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/NormalizedShort4.cs

@@ -112,6 +112,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Rg32.cs

@@ -93,6 +93,10 @@ public void FromVector4(Vector4 vector)
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Rgb24.cs

@@ -156,6 +156,10 @@ public void FromGray16(Gray16 source)
             this.B = rgb;
         }
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromVector4(source.ToVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromRgb24(Rgb24 source) => this = source;

src/ImageSharp/PixelFormats/PixelImplementations/Rgb48.cs

@@ -126,6 +126,10 @@ public void FromBgra32(Bgra32 source)
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromRgba64(Rgba64 source) => this = source.Rgb;
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source)

src/ImageSharp/PixelFormats/PixelImplementations/Rgba1010102.cs

@@ -99,6 +99,10 @@ public Vector4 ToVector4()
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());

src/ImageSharp/PixelFormats/PixelImplementations/Rgba32.cs

@@ -266,6 +266,10 @@ public void FromBgra32(Bgra32 source)
             this.A = source.A;
         }
 
+        /// <inheritdoc />
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source)

src/ImageSharp/PixelFormats/PixelImplementations/Rgba64.cs

@@ -9,7 +9,7 @@
 namespace SixLabors.ImageSharp.PixelFormats
 {
     /// <summary>
-    /// Packed pixel type containing four 16-bit unsigned normalized values ranging from 0 to 635535.
+    /// Packed pixel type containing four 16-bit unsigned normalized values ranging from 0 to 65535.
     /// <para>
     /// Ranges from [0, 0, 0, 0] to [1, 1, 1, 1] in vector form.
     /// </para>
@@ -154,6 +154,10 @@ public void FromBgra32(Bgra32 source)
             this.A = ImageMaths.UpscaleFrom8BitTo16Bit(source.A);
         }
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source)

src/ImageSharp/PixelFormats/PixelImplementations/RgbaVector.cs

@@ -134,6 +134,10 @@ public void FromVector4(Vector4 vector)
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromBgra32(Bgra32 source) => this.FromScaledVector4(source.ToScaledVector4());
 
+        /// <inheritdoc/>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public void FromBgra5551(Bgra5551 source) => this.FromScaledVector4(source.ToScaledVector4());
+
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
         public void FromGray8(Gray8 source) => this.FromScaledVector4(source.ToScaledVector4());
@@ -152,10 +156,7 @@ public void FromVector4(Vector4 vector)
 
         /// <inheritdoc />
         [MethodImpl(InliningOptions.ShortMethod)]
-        public void ToRgba32(ref Rgba32 dest)
-        {
-            dest.FromScaledVector4(this.ToScaledVector4());
-        }
+        public void ToRgba32(ref Rgba32 dest) => dest.FromScaledVector4(this.ToScaledVector4());
 
         /// <inheritdoc/>
         [MethodImpl(InliningOptions.ShortMethod)]