NormalizedByte2 Add NormalizedByte4

src/ImageSharp/Colors/PackedPixel/NormalizedByte2.cs

@@ -19,9 +19,14 @@ namespace ImageSharp
         private static readonly Vector4 MaxBytes = new Vector4(255);
 
         /// <summary>
-        /// The half vector value.
+        /// The half the maximum byte value.
         /// </summary>
-        private static readonly Vector4 Half = new Vector4(0.5F);
+        private static readonly Vector4 Half = new Vector4(127);
+
+        /// <summary>
+        /// The vector value used for rounding.
+        /// </summary>
+        private static readonly Vector4 Round = new Vector4(.5F);
 
         /// <summary>
         /// Initializes a new instance of the <see cref="NormalizedByte2"/> struct.
@@ -106,40 +111,47 @@ namespace ImageSharp
         /// <inheritdoc />
         public void PackFromBytes(byte x, byte y, byte z, byte w)
         {
-            this.PackFromVector4(new Vector4(x, y, z, w) / MaxBytes);
+            Vector4 vector = new Vector4(x, y, z, w);
+            vector -= Round;
+            vector -= Half;
+            vector -= Round;
+            vector /= Half;
+            this.PackFromVector4(vector);
         }
 
         /// <inheritdoc />
         public void ToBytes(byte[] bytes, int startIndex, ComponentOrder componentOrder)
         {
             Vector4 vector = this.ToVector4();
-            vector *= MaxBytes;
+            vector *= Half;
+            vector += Round;
             vector += Half;
+            vector += Round;
             vector = Vector4.Clamp(vector, Vector4.Zero, MaxBytes);
 
             switch (componentOrder)
             {
                 case ComponentOrder.ZYX:
-                    bytes[startIndex] = (byte)vector.Z;
+                    bytes[startIndex] = 0;
                     bytes[startIndex + 1] = (byte)vector.Y;
                     bytes[startIndex + 2] = (byte)vector.X;
                     break;
                 case ComponentOrder.ZYXW:
-                    bytes[startIndex] = (byte)vector.Z;
+                    bytes[startIndex] = 0;
                     bytes[startIndex + 1] = (byte)vector.Y;
                     bytes[startIndex + 2] = (byte)vector.X;
-                    bytes[startIndex + 3] = (byte)vector.W;
+                    bytes[startIndex + 3] = 255;
                     break;
                 case ComponentOrder.XYZ:
                     bytes[startIndex] = (byte)vector.X;
                     bytes[startIndex + 1] = (byte)vector.Y;
-                    bytes[startIndex + 2] = (byte)vector.Z;
+                    bytes[startIndex + 2] = 0;
                     break;
                 case ComponentOrder.XYZW:
                     bytes[startIndex] = (byte)vector.X;
                     bytes[startIndex + 1] = (byte)vector.Y;
-                    bytes[startIndex + 2] = (byte)vector.Z;
-                    bytes[startIndex + 3] = (byte)vector.W;
+                    bytes[startIndex + 2] = 0;
+                    bytes[startIndex + 3] = 255;
                     break;
                 default:
                     throw new NotSupportedException();
@@ -178,8 +190,8 @@ namespace ImageSharp
         /// <returns>The <see cref="ushort"/> containing the packed values.</returns>
         private static ushort Pack(float x, float y)
         {
-            int byte2 = (((ushort)Math.Round(x.Clamp(-1F, 1F) * 127F)) & 0xFF) << 0;
-            int byte1 = (((ushort)Math.Round(y.Clamp(-1F, 1F) * 127F)) & 0xFF) << 8;
+            int byte2 = ((ushort)Math.Round(x.Clamp(-1F, 1F) * 127F) & 0xFF) << 0;
+            int byte1 = ((ushort)Math.Round(y.Clamp(-1F, 1F) * 127F) & 0xFF) << 8;
 
             return (ushort)(byte2 | byte1);
         }

src/ImageSharp/Colors/PackedPixel/NormalizedByte4.cs

@@ -0,0 +1,197 @@
+// <copyright file="NormalizedByte4.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp
+{
+    using System;
+    using System.Numerics;
+
+    /// <summary>
+    /// Packed pixel type containing four 8-bit signed normalized values, ranging from −1 to 1.
+    /// </summary>
+    public struct NormalizedByte4 : IPackedPixel<uint>, IEquatable<NormalizedByte4>
+    {
+        /// <summary>
+        /// The maximum byte value.
+        /// </summary>
+        private static readonly Vector4 MaxBytes = new Vector4(255);
+
+        /// <summary>
+        /// The half the maximum byte value.
+        /// </summary>
+        private static readonly Vector4 Half = new Vector4(127);
+
+        /// <summary>
+        /// The vector value used for rounding.
+        /// </summary>
+        private static readonly Vector4 Round = new Vector4(.5F);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="NormalizedByte4"/> struct.
+        /// </summary>
+        /// <param name="vector">The vector containing the component values.</param>
+        public NormalizedByte4(Vector4 vector)
+        {
+            this.PackedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="NormalizedByte4"/> struct.
+        /// </summary>
+        /// <param name="x">The x-component.</param>
+        /// <param name="y">The y-component.</param>
+        /// <param name="z">The z-component.</param>
+        /// <param name="w">The w-component.</param>
+        public NormalizedByte4(float x, float y, float z, float w)
+        {
+            this.PackedValue = Pack(x, y, z, w);
+        }
+
+        /// <inheritdoc />
+        public uint PackedValue { get; set; }
+
+        /// <summary>
+        /// Compares two <see cref="NormalizedByte4"/> objects for equality.
+        /// </summary>
+        /// <param name="left">
+        /// The <see cref="NormalizedByte4"/> on the left side of the operand.
+        /// </param>
+        /// <param name="right">
+        /// The <see cref="NormalizedByte4"/> on the right side of the operand.
+        /// </param>
+        /// <returns>
+        /// True if the <paramref name="left"/> parameter is equal to the <paramref name="right"/> parameter; otherwise, false.
+        /// </returns>
+        public static bool operator ==(NormalizedByte4 left, NormalizedByte4 right)
+        {
+            return left.PackedValue == right.PackedValue;
+        }
+
+        /// <summary>
+        /// Compares two <see cref="NormalizedByte4"/> objects for equality.
+        /// </summary>
+        /// <param name="left">
+        /// The <see cref="NormalizedByte4"/> on the left side of the operand.
+        /// </param>
+        /// <param name="right">
+        /// The <see cref="NormalizedByte4"/> on the right side of the operand.
+        /// </param>
+        /// <returns>
+        /// True if the <paramref name="left"/> parameter is not equal to the <paramref name="right"/> parameter; otherwise, false.
+        /// </returns>
+        public static bool operator !=(NormalizedByte4 left, NormalizedByte4 right)
+        {
+            return left.PackedValue != right.PackedValue;
+        }
+
+        /// <inheritdoc />
+        public void PackFromVector4(Vector4 vector)
+        {
+            this.PackedValue = Pack(vector.X, vector.Y, vector.Z, vector.W);
+        }
+
+        /// <inheritdoc />
+        public Vector4 ToVector4()
+        {
+            return new Vector4(
+                (sbyte)((this.PackedValue >> 0) & 0xFF) / 127F,
+                (sbyte)((this.PackedValue >> 8) & 0xFF) / 127F,
+                (sbyte)((this.PackedValue >> 16) & 0xFF) / 127F,
+                (sbyte)((this.PackedValue >> 24) & 0xFF) / 127F);
+        }
+
+        /// <inheritdoc />
+        public void PackFromBytes(byte x, byte y, byte z, byte w)
+        {
+            Vector4 vector = new Vector4(x, y, z, w);
+            vector -= Round;
+            vector -= Half;
+            vector -= Round;
+            vector /= Half;
+            this.PackFromVector4(vector);
+        }
+
+        /// <inheritdoc />
+        public void ToBytes(byte[] bytes, int startIndex, ComponentOrder componentOrder)
+        {
+            Vector4 vector = this.ToVector4();
+            vector *= Half;
+            vector += Round;
+            vector += Half;
+            vector += Round;
+            vector = Vector4.Clamp(vector, Vector4.Zero, MaxBytes);
+
+            switch (componentOrder)
+            {
+                case ComponentOrder.ZYX:
+                    bytes[startIndex] = (byte)vector.Z;
+                    bytes[startIndex + 1] = (byte)vector.Y;
+                    bytes[startIndex + 2] = (byte)vector.X;
+                    break;
+                case ComponentOrder.ZYXW:
+                    bytes[startIndex] = (byte)vector.Z;
+                    bytes[startIndex + 1] = (byte)vector.Y;
+                    bytes[startIndex + 2] = (byte)vector.X;
+                    bytes[startIndex + 3] = (byte)vector.W;
+                    break;
+                case ComponentOrder.XYZ:
+                    bytes[startIndex] = (byte)vector.X;
+                    bytes[startIndex + 1] = (byte)vector.Y;
+                    bytes[startIndex + 2] = (byte)vector.Z;
+                    break;
+                case ComponentOrder.XYZW:
+                    bytes[startIndex] = (byte)vector.X;
+                    bytes[startIndex + 1] = (byte)vector.Y;
+                    bytes[startIndex + 2] = (byte)vector.Z;
+                    bytes[startIndex + 3] = (byte)vector.W;
+                    break;
+                default:
+                    throw new NotSupportedException();
+            }
+        }
+
+        /// <inheritdoc />
+        public override bool Equals(object obj)
+        {
+            return (obj is NormalizedByte4) && this.Equals((NormalizedByte4)obj);
+        }
+
+        /// <inheritdoc />
+        public bool Equals(NormalizedByte4 other)
+        {
+            return this.PackedValue == other.PackedValue;
+        }
+
+        /// <inheritdoc />
+        public override int GetHashCode()
+        {
+            return this.PackedValue.GetHashCode();
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return this.PackedValue.ToString("X");
+        }
+
+        /// <summary>
+        /// Packs the <see cref="float"/> components into a <see cref="uint"/>.
+        /// </summary>
+        /// <param name="x">The x-component</param>
+        /// <param name="y">The y-component</param>
+        /// <param name="z">The z-component</param>
+        /// <param name="w">The w-component</param>
+        /// <returns>The <see cref="uint"/> containing the packed values.</returns>
+        private static uint Pack(float x, float y, float z, float w)
+        {
+            uint byte4 = ((uint)Math.Round(x.Clamp(-1F, 1F) * 127F) & 0xFF) << 0;
+            uint byte3 = ((uint)Math.Round(y.Clamp(-1F, 1F) * 127F) & 0xFF) << 8;
+            uint byte2 = ((uint)Math.Round(z.Clamp(-1F, 1F) * 127F) & 0xFF) << 16;
+            uint byte1 = ((uint)Math.Round(w.Clamp(-1F, 1F) * 127F) & 0xFF) << 24;
+
+            return byte4 | byte3 | byte2 | byte1;
+        }
+    }
+}

tests/ImageSharp.Tests/Colors/PackedPixelTests.cs

@@ -383,7 +383,7 @@ namespace ImageSharp.Tests.Colors
             Assert.True(Equal(Vector2.One, new NormalizedByte2(Vector2.One * 1234.0f).ToVector2()));
             Assert.True(Equal(-Vector2.One, new NormalizedByte2(Vector2.One * -1234.0f).ToVector2()));
 
-            // Test ToVector2
+            // Test ToVector4
             Assert.True(Equal(new Vector4(1, 1, 0, 1), new NormalizedByte2(Vector2.One).ToVector4()));
             Assert.True(Equal(new Vector4(0, 0, 0, 1), new NormalizedByte2(Vector2.Zero).ToVector4()));
 
@@ -391,6 +391,9 @@ namespace ImageSharp.Tests.Colors
             float x = 0.1f;
             float y = -0.3f;
             Assert.Equal(0xda0d, new NormalizedByte2(x, y).PackedValue);
+            NormalizedByte2 n = new NormalizedByte2();
+            n.PackFromBytes(141, 90, 0, 0);
+            Assert.Equal(0xda0d, n.PackedValue);
 
             byte[] rgb = new byte[3];
             byte[] rgba = new byte[4];
@@ -398,16 +401,71 @@ namespace ImageSharp.Tests.Colors
             byte[] bgra = new byte[4];
 
             new NormalizedByte2(x, y).ToBytes(rgb, 0, ComponentOrder.XYZ);
-            Assert.Equal(rgb, new byte[] { 26, 0, 0 });
+            Assert.Equal(rgb, new byte[] { 141, 90, 0 });
 
             new NormalizedByte2(x, y).ToBytes(rgba, 0, ComponentOrder.XYZW);
-            Assert.Equal(rgba, new byte[] { 26, 0, 0, 255 });
+            Assert.Equal(rgba, new byte[] { 141, 90, 0, 255 });
 
             new NormalizedByte2(x, y).ToBytes(bgr, 0, ComponentOrder.ZYX);
-            Assert.Equal(bgr, new byte[] { 0, 0, 26 });
+            Assert.Equal(bgr, new byte[] { 0, 90, 141 });
 
             new NormalizedByte2(x, y).ToBytes(bgra, 0, ComponentOrder.ZYXW);
-            Assert.Equal(bgra, new byte[] { 0, 0, 26, 255 });
+            Assert.Equal(bgra, new byte[] { 0, 90, 141, 255 });
+        }
+
+        [Fact]
+        public void NormalizedByte4()
+        {
+            // Test PackedValue
+            Assert.Equal((uint)0x0, new NormalizedByte4(Vector4.Zero).PackedValue);
+            Assert.Equal((uint)0x7F7F7F7F, new NormalizedByte4(Vector4.One).PackedValue);
+            Assert.Equal(0x81818181, new NormalizedByte4(-Vector4.One).PackedValue);
+
+            // Test ToVector4
+            Assert.True(Equal(Vector4.One, new NormalizedByte4(Vector4.One).ToVector4()));
+            Assert.True(Equal(Vector4.Zero, new NormalizedByte4(Vector4.Zero).ToVector4()));
+            Assert.True(Equal(-Vector4.One, new NormalizedByte4(-Vector4.One).ToVector4()));
+            Assert.True(Equal(Vector4.One, new NormalizedByte4(Vector4.One * 1234.0f).ToVector4()));
+            Assert.True(Equal(-Vector4.One, new NormalizedByte4(Vector4.One * -1234.0f).ToVector4()));
+
+            // Test Ordering
+            float x = 0.1f;
+            float y = -0.3f;
+            float z = 0.5f;
+            float w = -0.7f;
+            Assert.Equal(0xA740DA0D, new NormalizedByte4(x, y, z, w).PackedValue);
+            NormalizedByte4 n = new NormalizedByte4();
+            n.PackFromBytes(141, 90, 192, 39);
+            Assert.Equal(0xA740DA0D, n.PackedValue);
+
+            Assert.Equal((uint)958796544, new NormalizedByte4(0.0008f, 0.15f, 0.30f, 0.45f).PackedValue);
+
+            byte[] rgb = new byte[3];
+            byte[] rgba = new byte[4];
+            byte[] bgr = new byte[3];
+            byte[] bgra = new byte[4];
+
+            new NormalizedByte4(x, y, z, w).ToBytes(rgb, 0, ComponentOrder.XYZ);
+            Assert.Equal(rgb, new byte[] { 141, 90, 192 });
+
+            new NormalizedByte4(x, y, z, w).ToBytes(rgba, 0, ComponentOrder.XYZW);
+            Assert.Equal(rgba, new byte[] { 141, 90, 192, 39 });
+
+            new NormalizedByte4(x, y, z, w).ToBytes(bgr, 0, ComponentOrder.ZYX);
+            Assert.Equal(bgr, new byte[] { 192, 90, 141 });
+
+            new NormalizedByte4(x, y, z, w).ToBytes(bgra, 0, ComponentOrder.ZYXW);
+            Assert.Equal(bgra, new byte[] { 192, 90, 141, 39 });
+
+            // http://community.monogame.net/t/normalizedbyte4-texture2d-gives-different-results-from-xna/8012/8
+            NormalizedByte4 r = new NormalizedByte4();
+            r.PackFromBytes(9, 115, 202, 127);
+            r.ToBytes(rgba, 0, ComponentOrder.XYZW);
+            Assert.Equal(rgba, new byte[] { 9, 115, 202, 127 });
+
+            r.PackedValue = 0x7FCA7309;
+            r.ToBytes(rgba, 0, ComponentOrder.XYZW);
+            Assert.Equal(rgba, new byte[] { 9, 115, 202, 127 });
         }
 
         // Comparison helpers with small tolerance to allow for floating point rounding during computations.

tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs

@@ -60,6 +60,7 @@ namespace ImageSharp.Tests
                 // Image<HalfVector2, uint> image = file.CreateImage().To<HalfVector2, uint>();
                 // Image<HalfVector4, ulong> image = file.CreateImage().To<HalfVector4, ulong>();
                 // Image<NormalizedByte2, ushort> image = file.CreateImage().To<NormalizedByte2, ushort>();
+                // Image<NormalizedByte4, uint> image = file.CreateImage().To<NormalizedByte4, uint>();
 
                 using (FileStream output = File.OpenWrite($"{path}/{file.FileName}"))
                 {