Color to CMYK conversion

Former-commit-id: be686be849ba8b99cecb3e9188c7d62cff015a2a
Former-commit-id: 832c449448d72e536b546493ff5a3f045f6b60f4
Former-commit-id: e73973e1db53ab8c7f626b7720d74922810fc674

src/ImageProcessor/Colors/Color.cs

@@ -174,6 +174,24 @@ namespace ImageProcessor
             return new Color(color.R / 255f, color.G / 255f, color.B / 255f, color.A / 255f);
         }
 
+        /// <summary>
+        /// Allows the implicit conversion of an instance of <see cref="Cmyk"/> to a
+        /// <see cref="Color"/>.
+        /// </summary>
+        /// <param name="cmykColor">
+        /// The instance of <see cref="Cmyk"/> to convert.
+        /// </param>
+        /// <returns>
+        /// An instance of <see cref="Color"/>.
+        /// </returns>
+        public static implicit operator Color(Cmyk cmykColor)
+        {
+            float r = (1 - cmykColor.C) * (1 - cmykColor.K);
+            float g = (1 - cmykColor.M) * (1 - cmykColor.K);
+            float b = (1 - cmykColor.Y) * (1 - cmykColor.K);
+            return new Color(r, g, b);
+        }
+
         /// <summary>
         /// Allows the implicit conversion of an instance of <see cref="Hsv"/> to a
         /// <see cref="Color"/>.

src/ImageProcessor/Colors/Formats/Bgra32.cs

@@ -212,24 +212,6 @@ namespace ImageProcessor
             return new Bgra32(b, g, r, 255);
         }
 
-        /// <summary>
-        /// Allows the implicit conversion of an instance of <see cref="Cmyk"/> to a
-        /// <see cref="Bgra32"/>.
-        /// </summary>
-        /// <param name="cmykColor">
-        /// The instance of <see cref="Cmyk"/> to convert.
-        /// </param>
-        /// <returns>
-        /// An instance of <see cref="Bgra32"/>.
-        /// </returns>
-        public static implicit operator Bgra32(Cmyk cmykColor)
-        {
-            int red = Convert.ToInt32((1 - (cmykColor.C / 100)) * (1 - (cmykColor.K / 100)) * 255.0);
-            int green = Convert.ToInt32((1 - (cmykColor.M / 100)) * (1 - (cmykColor.K / 100)) * 255.0);
-            int blue = Convert.ToInt32((1 - (cmykColor.Y / 100)) * (1 - (cmykColor.K / 100)) * 255.0);
-            return new Bgra32(blue.ToByte(), green.ToByte(), red.ToByte());
-        }
-
         /// <summary>
         /// Compares two <see cref="Bgra32"/> objects. The result specifies whether the values
         /// of the <see cref="Bgra32.B"/>, <see cref="Bgra32.G"/>, <see cref="Bgra32.R"/>, and <see cref="Bgra32.A"/>

src/ImageProcessor/Colors/Formats/Cmyk.cs

@@ -7,6 +7,7 @@ namespace ImageProcessor
 {
     using System;
     using System.ComponentModel;
+    using System.Numerics;
 
     /// <summary>
     /// Represents an CMYK (cyan, magenta, yellow, keyline) color.
@@ -19,60 +20,63 @@ namespace ImageProcessor
         public static readonly Cmyk Empty = default(Cmyk);
 
         /// <summary>
-        /// Gets the cyan color component.
+        /// The epsilon for comparing floating point numbers.
         /// </summary>
-        /// <remarks>A value ranging between 0 and 100.</remarks>
-        public readonly float C;
+        private const float Epsilon = 0.0001f;
 
         /// <summary>
-        /// Gets the magenta color component.
+        /// The backing vector for SIMD support.
         /// </summary>
-        /// <remarks>A value ranging between 0 and 100.</remarks>
-        public readonly float M;
+        private Vector4 backingVector;
 
         /// <summary>
-        /// Gets the yellow color component.
+        /// Initializes a new instance of the <see cref="Cmyk"/> struct.
         /// </summary>
-        /// <remarks>A value ranging between 0 and 100.</remarks>
-        public readonly float Y;
+        /// <param name="cyan">The cyan component.</param>
+        /// <param name="magenta">The magenta component.</param>
+        /// <param name="yellow">The yellow component.</param>
+        /// <param name="keyline">The keyline black component.</param>
+        public Cmyk(float cyan, float magenta, float yellow, float keyline)
+            : this()
+        {
+            this.backingVector.X = Clamp(cyan);
+            this.backingVector.Y = Clamp(magenta);
+            this.backingVector.Z = Clamp(yellow);
+            this.backingVector.W = Clamp(keyline);
+        }
 
         /// <summary>
-        /// Gets the keyline black color component.
+        /// Gets the cyan color component.
+        /// <remarks>A value ranging between 0 and 1.</remarks>
         /// </summary>
-        /// <remarks>A value ranging between 0 and 100.</remarks>
-        public readonly float K;
+        public float C => this.backingVector.X;
 
         /// <summary>
-        /// The epsilon for comparing floating point numbers.
+        /// Gets the magenta color component.
+        /// <remarks>A value ranging between 0 and 1.</remarks>
         /// </summary>
-        private const float Epsilon = 0.0001f;
+        public float M => this.backingVector.Y;
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="Cmyk"/> struct.
+        /// Gets the yellow color component.
+        /// <remarks>A value ranging between 0 and 1.</remarks>
         /// </summary>
-        /// <param name="cyan">The cyan component.</param>
-        /// <param name="magenta">The magenta component.</param>
-        /// <param name="yellow">The yellow component.</param>
-        /// <param name="keyline">The keyline black component.</param>
-        public Cmyk(float cyan, float magenta, float yellow, float keyline)
-        {
-            this.C = Clamp(cyan);
-            this.M = Clamp(magenta);
-            this.Y = Clamp(yellow);
-            this.K = Clamp(keyline);
-        }
+        public float Y => this.backingVector.Z;
+
+        /// <summary>
+        /// Gets the keyline black color component.
+        /// <remarks>A value ranging between 0 and 1.</remarks>
+        /// </summary>
+        public float K => this.backingVector.W;
 
         /// <summary>
         /// Gets a value indicating whether this <see cref="Cmyk"/> is empty.
         /// </summary>
         [EditorBrowsable(EditorBrowsableState.Never)]
-        public bool IsEmpty => Math.Abs(this.C) < Epsilon
-                            && Math.Abs(this.M) < Epsilon
-                            && Math.Abs(this.Y) < Epsilon
-                            && Math.Abs(this.K) < Epsilon;
+        public bool IsEmpty => this.backingVector.Equals(default(Vector4));
 
         /// <summary>
-        /// Allows the implicit conversion of an instance of <see cref="Bgra32"/> to a
+        /// Allows the implicit conversion of an instance of <see cref="Color"/> to a
         /// <see cref="Cmyk"/>.
         /// </summary>
         /// <param name="color">
@@ -81,30 +85,30 @@ namespace ImageProcessor
         /// <returns>
         /// An instance of <see cref="Cmyk"/>.
         /// </returns>
-        public static implicit operator Cmyk(Bgra32 color)
+        public static implicit operator Cmyk(Color color)
         {
-            float c = (255f - color.R) / 255;
-            float m = (255f - color.G) / 255;
-            float y = (255f - color.B) / 255;
+            color = color.Limited;
+
+            float c = 1f - color.R;
+            float m = 1f - color.G;
+            float y = 1f - color.B;
 
             float k = Math.Min(c, Math.Min(m, y));
 
-            if (Math.Abs(k - 1.0) <= Epsilon)
+            if (Math.Abs(k - 1.0f) <= Epsilon)
             {
-                return new Cmyk(0, 0, 0, 100);
+                return new Cmyk(0, 0, 0, 1);
             }
 
-            c = ((c - k) / (1 - k)) * 100;
-            m = ((m - k) / (1 - k)) * 100;
-            y = ((y - k) / (1 - k)) * 100;
+            c = (c - k) / (1 - k);
+            m = (m - k) / (1 - k);
+            y = (y - k) / (1 - k);
 
-            return new Cmyk(c, m, y, k * 100);
+            return new Cmyk(c, m, y, k);
         }
 
         /// <summary>
-        /// Compares two <see cref="Cmyk"/> objects. The result specifies whether the values
-        /// of the <see cref="Cmyk.C"/>, <see cref="Cmyk.M"/>, <see cref="Cmyk.Y"/>, and <see cref="Cmyk.K"/>
-        /// properties of the two <see cref="Cmyk"/> objects are equal.
+        /// Compares two <see cref="Cmyk"/> objects for equality.
         /// </summary>
         /// <param name="left">
         /// The <see cref="Cmyk"/> on the left side of the operand.
@@ -121,9 +125,7 @@ namespace ImageProcessor
         }
 
         /// <summary>
-        /// Compares two <see cref="Cmyk"/> objects. The result specifies whether the values
-        /// of the <see cref="Cmyk.C"/>, <see cref="Cmyk.M"/>, <see cref="Cmyk.Y"/>, and <see cref="Cmyk.K"/>
-        /// properties of the two <see cref="Cmyk"/> objects are unequal.
+        /// Compares two <see cref="Cmyk"/> objects for inequality
         /// </summary>
         /// <param name="left">
         /// The <see cref="Cmyk"/> on the left side of the operand.
@@ -152,39 +154,19 @@ namespace ImageProcessor
             {
                 Cmyk color = (Cmyk)obj;
 
-                return Math.Abs(this.C - color.C) < Epsilon
-                    && Math.Abs(this.M - color.M) < Epsilon
-                    && Math.Abs(this.Y - color.Y) < Epsilon
-                    && Math.Abs(this.K - color.K) < Epsilon;
+                return this.backingVector == color.backingVector;
             }
 
             return false;
         }
 
-        /// <summary>
-        /// Returns the hash code for this instance.
-        /// </summary>
-        /// <returns>
-        /// A 32-bit signed integer that is the hash code for this instance.
-        /// </returns>
+        /// <inheritdoc/>
         public override int GetHashCode()
         {
-            unchecked
-            {
-                int hashCode = this.C.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.M.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.Y.GetHashCode();
-                hashCode = (hashCode * 397) ^ this.K.GetHashCode();
-                return hashCode;
-            }
+            return GetHashCode(this);
         }
 
-        /// <summary>
-        /// Returns the fully qualified type name of this instance.
-        /// </summary>
-        /// <returns>
-        /// A <see cref="T:System.String"/> containing a fully qualified type name.
-        /// </returns>
+        /// <inheritdoc/>
         public override string ToString()
         {
             if (this.IsEmpty)
@@ -195,19 +177,10 @@ namespace ImageProcessor
             return $"Cmyk [ C={this.C:#0.##}, M={this.M:#0.##}, Y={this.Y:#0.##}, K={this.K:#0.##}]";
         }
 
-        /// <summary>
-        /// Indicates whether the current object is equal to another object of the same type.
-        /// </summary>
-        /// <returns>
-        /// True if the current object is equal to the <paramref name="other"/> parameter; otherwise, false.
-        /// </returns>
-        /// <param name="other">An object to compare with this object.</param>
+        /// <inheritdoc/>
         public bool Equals(Cmyk other)
         {
-            return Math.Abs(this.C - other.C) < Epsilon
-                && Math.Abs(this.M - other.M) < Epsilon
-                && Math.Abs(this.Y - other.Y) < Epsilon
-                && Math.Abs(this.K - other.Y) < Epsilon;
+            return this.backingVector.Equals(other.backingVector);
         }
 
         /// <summary>
@@ -223,5 +196,16 @@ namespace ImageProcessor
         {
             return value.Clamp(0, 100);
         }
+
+        /// <summary>
+        /// Returns the hash code for this instance.
+        /// </summary>
+        /// <param name="color">
+        /// The instance of <see cref="Cmyk"/> to return the hash code for.
+        /// </param>
+        /// <returns>
+        /// A 32-bit signed integer that is the hash code for this instance.
+        /// </returns>
+        private static int GetHashCode(Cmyk color) => color.backingVector.GetHashCode();
     }
 }

src/ImageProcessor/Colors/Formats/Hsv.cs

@@ -122,7 +122,7 @@ namespace ImageProcessor
         }
 
         /// <summary>
-        /// Compares two <see cref="Hsv"/> objects for equality
+        /// Compares two <see cref="Hsv"/> objects for equality.
         /// </summary>
         /// <param name="left">
         /// The <see cref="Hsv"/> on the left side of the operand.

tests/ImageProcessor.Tests/Colors/ColorConversionTests.cs

@@ -17,7 +17,11 @@ namespace ImageProcessor.Tests
 
     /// <summary>
     /// Test conversion between the various color structs.
-    /// </summary>
+    ///  </summary>
+    /// <remarks>
+    /// Output values have been compared with <see cref="http://colormine.org/color-converter"/>
+    /// and <see cref="http://www.colorhexa.com/"/> for accuracy.
+    /// </remarks>
     public class ColorConversionTests
     {
         /// <summary>
@@ -163,90 +167,90 @@ namespace ImageProcessor.Tests
             for (int i = 0; i < 1000; i++)
             {
                 Color color4 = new Color(random.Next(1), random.Next(1), random.Next(1));
-                Hsv hsb4 = color4;
-                Assert.Equal(color4, (Color)hsb4);
+                Hsv hsv4 = color4;
+                Assert.Equal(color4, (Color)hsv4);
             }
         }
 
         /// <summary>
-        /// Tests the implicit conversion from <see cref="Bgra32"/> to <see cref="Cmyk"/>.
+        /// Tests the implicit conversion from <see cref="Color"/> to <see cref="Cmyk"/>.
         /// </summary>
         [Fact]
         [SuppressMessage("StyleCop.CSharp.NamingRules", "SA1305:FieldNamesMustNotUseHungarianNotation",
             Justification = "Reviewed. Suppression is OK here.")]
-        public void BgrToCmyk()
+        public void ColorToCmyk()
         {
             // White
-            Bgra32 color = new Bgra32(255, 255, 255, 255);
+            Color color = new Color(1, 1, 1);
             Cmyk cmyk = color;
 
-            Assert.Equal(0, cmyk.C);
-            Assert.Equal(0, cmyk.M);
-            Assert.Equal(0, cmyk.Y);
-            Assert.Equal(0, cmyk.K);
+            Assert.Equal(0, cmyk.C, 1);
+            Assert.Equal(0, cmyk.M, 1);
+            Assert.Equal(0, cmyk.Y, 1);
+            Assert.Equal(0, cmyk.K, 1);
 
             // Black
-            Bgra32 color2 = new Bgra32(0, 0, 0, 255);
+            Color color2 = new Color(0, 0, 0);
             Cmyk cmyk2 = color2;
-            Assert.Equal(0, cmyk2.C);
-            Assert.Equal(0, cmyk2.M);
-            Assert.Equal(0, cmyk2.Y);
-            Assert.Equal(100, cmyk2.K);
+            Assert.Equal(0, cmyk2.C, 1);
+            Assert.Equal(0, cmyk2.M, 1);
+            Assert.Equal(0, cmyk2.Y, 1);
+            Assert.Equal(1, cmyk2.K, 1);
 
             // Grey
-            Bgra32 color3 = new Bgra32(128, 128, 128, 255);
+            Color color3 = new Color(128 / 255f, 128 / 255f, 128 / 255f);
             Cmyk cmyk3 = color3;
-            Assert.Equal(0, cmyk3.C);
-            Assert.Equal(0, cmyk3.M);
-            Assert.Equal(0, cmyk3.Y);
-            Assert.Equal(49.8, cmyk3.K, 1); // Checked with other tools.
+            Assert.Equal(0f, cmyk3.C, 1);
+            Assert.Equal(0f, cmyk3.M, 1);
+            Assert.Equal(0f, cmyk3.Y, 1);
+            Assert.Equal(0.498, cmyk3.K, 2); // Checked with other online converters.
 
             // Cyan
-            Bgra32 color4 = new Bgra32(255, 255, 0, 255);
+            Color color4 = new Color(0, 1, 1);
             Cmyk cmyk4 = color4;
-            Assert.Equal(100, cmyk4.C);
-            Assert.Equal(0, cmyk4.M);
-            Assert.Equal(0, cmyk4.Y);
-            Assert.Equal(0, cmyk4.K);
+            Assert.Equal(1, cmyk4.C, 1);
+            Assert.Equal(0f, cmyk4.M, 1);
+            Assert.Equal(0f, cmyk4.Y, 1);
+            Assert.Equal(0f, cmyk4.K, 1);
         }
 
         /// <summary>
-        /// Tests the implicit conversion from <see cref="Hsv"/> to <see cref="Bgra32"/>.
+        /// Tests the implicit conversion from <see cref="Cmyk"/> to <see cref="Color"/>.
         /// </summary>
         [Fact]
-        public void CmykToBgr()
+        public void CmykToColor()
         {
             // Dark moderate pink.
-            Cmyk cmyk = new Cmyk(49.8f, 74.9f, 58.4f, 0);
-            Bgra32 bgra32 = cmyk;
+            Cmyk cmyk = new Cmyk(0f, .5f, .171f, .498f);
+            Color color = cmyk;
 
-            Assert.Equal(bgra32.B, 106);
-            Assert.Equal(bgra32.G, 64);
-            Assert.Equal(bgra32.R, 128);
+            Assert.Equal(color.R, 128 / 255f, 1);
+            Assert.Equal(color.G, 64 / 255f, 1);
+            Assert.Equal(color.B, 106 / 255f, 1);
 
             // Ochre
-            Cmyk cmyk2 = new Cmyk(20, 53.3f, 86.7f, 0);
-            Bgra32 bgra2 = cmyk2;
+            Cmyk cmyk2 = new Cmyk(0, .416f, .833f, .199f);
+            Color color2 = cmyk2;
 
-            Assert.Equal(bgra2.B, 34);
-            Assert.Equal(bgra2.G, 119);
-            Assert.Equal(bgra2.R, 204);
+            Assert.Equal(color2.R, 204 / 255f, 1);
+            Assert.Equal(color2.G, 119 / 255f, 1);
+            Assert.Equal(color2.B, 34 / 255f, 1);
 
             // White
             Cmyk cmyk3 = new Cmyk(0, 0, 0, 0);
-            Bgra32 bgra3 = cmyk3;
+            Color color3 = cmyk3;
 
-            Assert.Equal(bgra3.B, 255);
-            Assert.Equal(bgra3.G, 255);
-            Assert.Equal(bgra3.R, 255);
+            Assert.Equal(color3.R, 1f, 1);
+            Assert.Equal(color3.G, 1f, 1);
+            Assert.Equal(color3.B, 1f, 1);
 
             // Check others.
             Random random = new Random(0);
             for (int i = 0; i < 1000; i++)
             {
-                Bgra32 bgra4 = new Bgra32((byte)random.Next(255), (byte)random.Next(255), (byte)random.Next(255));
-                Cmyk cmyk4 = bgra4;
-                Assert.Equal(bgra4, (Bgra32)cmyk4);
+                Color color4 = new Color(random.Next(1), random.Next(1), random.Next(1));
+                Cmyk cmyk4 = color4;
+                Assert.Equal(color4, (Color)cmyk4);
             }
         }
     }