diff --git a/ThemeEditor.sln b/ThemeEditor.sln
index ade1b51..2ae0a68 100644
--- a/ThemeEditor.sln
+++ b/ThemeEditor.sln
@@ -41,8 +41,15 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "props", "props", "{A88815F2
 		build\Newtonsoft.Json.props = build\Newtonsoft.Json.props
 		build\ReactiveUI.props = build\ReactiveUI.props
 		build\Rx.props = build\Rx.props
+		build\XUnit.props = build\XUnit.props
 	EndProjectSection
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{F2D7C825-1AC1-45FF-A221-CEE80E2F2374}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ThemeEditor.Colors", "src\ThemeEditor.Colors\ThemeEditor.Colors.csproj", "{BFDD803E-2B9B-46A2-AC25-C77FD2376893}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ThemeEditor.Colors.UnitTests", "tests\ThemeEditor.Colors.UnitTests\ThemeEditor.Colors.UnitTests.csproj", "{E2079787-7F2F-46F8-BD56-2C226D883904}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -57,6 +64,14 @@ Global
 		{2B5611EB-1E0D-4EAB-96C9-821A965E496B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{2B5611EB-1E0D-4EAB-96C9-821A965E496B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{2B5611EB-1E0D-4EAB-96C9-821A965E496B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{BFDD803E-2B9B-46A2-AC25-C77FD2376893}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{BFDD803E-2B9B-46A2-AC25-C77FD2376893}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{BFDD803E-2B9B-46A2-AC25-C77FD2376893}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{BFDD803E-2B9B-46A2-AC25-C77FD2376893}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E2079787-7F2F-46F8-BD56-2C226D883904}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E2079787-7F2F-46F8-BD56-2C226D883904}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E2079787-7F2F-46F8-BD56-2C226D883904}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E2079787-7F2F-46F8-BD56-2C226D883904}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -68,6 +83,8 @@ Global
 		{497FBEFD-7228-4E2F-A947-9F416498E263} = {3353FD4A-FE9B-4670-86C9-09EF0F7CEDB2}
 		{9A80222C-EDE8-42AF-9D6D-76325FC4673F} = {3353FD4A-FE9B-4670-86C9-09EF0F7CEDB2}
 		{A88815F2-21C3-4EBA-8DBC-0A461EA7F82C} = {3353FD4A-FE9B-4670-86C9-09EF0F7CEDB2}
+		{BFDD803E-2B9B-46A2-AC25-C77FD2376893} = {219954C4-6A40-4D94-914E-148B7EBB718E}
+		{E2079787-7F2F-46F8-BD56-2C226D883904} = {F2D7C825-1AC1-45FF-A221-CEE80E2F2374}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {CF676549-9409-4598-8229-80E04B51ADC5}
diff --git a/src/ThemeEditor.Colors/HSV.cs b/src/ThemeEditor.Colors/HSV.cs
new file mode 100644
index 0000000..5d31e90
--- /dev/null
+++ b/src/ThemeEditor.Colors/HSV.cs
@@ -0,0 +1,98 @@
+using System;
+
+namespace ThemeEditor.Colors
+{
+    public readonly struct HSV
+    {
+        public double H { get; }
+        public double S { get; }
+        public double V { get; }
+
+        public HSV(double h, double s, double v)
+        {
+            H = h;
+            S = s;
+            V = v;
+        }
+
+        public HSV(HSV hsv)
+        {
+            H = hsv.H;
+            S = hsv.S;
+            V = hsv.V;
+        }
+
+        public HSV(RGB rgb)
+        {
+            HSV hsv = rgb.ToHSV();
+            H = hsv.H;
+            S = hsv.S;
+            V = hsv.V;
+        }
+
+        public RGB ToRGB() => ToRGB(H, S, V);
+
+        public static RGB ToRGB(double h, double s, double v)
+        {
+            double R = default;
+            double G = default;
+            double B = default;
+
+            if (s == 0)
+            {
+                R = G = B = Math.Round(v * 2.55);
+                return new RGB(R, G, B);
+            }
+
+            s = s / 100;
+            v = v / 100;
+            h /= 60;
+
+            var i = Math.Floor(h);
+            var f = h - i;
+            var p = v * (1 - s);
+            var q = v * (1 - s * f);
+            var t = v * (1 - s * (1 - f));
+
+            switch ((int)i)
+            {
+                case 0:
+                    R = v;
+                    G = t;
+                    B = p;
+                    break;
+                case 1:
+                    R = q;
+                    G = v;
+                    B = p;
+                    break;
+                case 2:
+                    R = p;
+                    G = v;
+                    B = t;
+                    break;
+                case 3:
+                    R = p;
+                    G = q;
+                    B = v;
+                    break;
+                case 4:
+                    R = t;
+                    G = p;
+                    B = v;
+                    break;
+                default:
+                    R = v;
+                    G = p;
+                    B = q;
+                    break;
+            }
+
+            R = Math.Round(R * 255);
+            G = Math.Round(G * 255);
+            B = Math.Round(B * 255);
+
+            return new RGB(R, G, B);
+        }
+    }
+}
diff --git a/src/ThemeEditor.Colors/RGB.cs b/src/ThemeEditor.Colors/RGB.cs
new file mode 100644
index 0000000..3c26d20
--- /dev/null
+++ b/src/ThemeEditor.Colors/RGB.cs
@@ -0,0 +1,109 @@
+using System;
+
+namespace ThemeEditor.Colors
+{
+    public readonly struct RGB
+    {
+        public double R { get; }
+        public double G { get; }
+        public double B { get; }
+
+        public RGB(double r, double g, double b)
+        {
+            R = r;
+            G = g;
+            B = b;
+        }
+
+        public RGB(RGB rgb)
+        {
+            R = rgb.R;
+            G = rgb.G;
+            B = rgb.B;
+        }
+
+        public RGB(HSV hsv)
+        {
+            RGB rgb = hsv.ToRGB();
+            R = rgb.R;
+            G = rgb.G;
+            B = rgb.B;
+        }
+
+        public HSV ToHSV() => ToHSV(R, G, B);
+
+        public static HSV ToHSV(double r, double g, double b)
+        {
+            double H = default;
+            double S = default;
+            double V = default;
+
+            var m = r;
+
+            if (g < m)
+            {
+                m = g;
+            }
+
+            if (b < m)
+            {
+                m = b;
+            }
+
+            var v = r;
+
+            if (g > v)
+            {
+                v = g;
+            }
+
+            if (b > v)
+            {
+                v = b;
+            }
+
+            var value = 100 * v / 255;
+            var delta = v - m;
+
+            if (v == 0.0)
+            {
+                S = 0;
+            }
+            else
+            {
+                S = 100 * delta / v;
+            }
+
+            if (S == 0)
+            {
+                H = 0;
+            }
+            else
+            {
+                if (r == v)
+                {
+                    H = 60.0 * (g - b) / delta;
+                }
+                else if (g == v)
+                {
+                    H = 120.0 + 60.0 * (b - r) / delta;
+                }
+                else if (b == v)
+                {
+                    H = 240.0 + 60.0 * (r - g) / delta;
+                }
+
+                if (H < 0.0)
+                {
+                    H = H + 360.0;
+                }
+            }
+
+            H = Math.Round(H);
+            S = Math.Round(S);
+            V = Math.Round(value);
+
+            return new HSV(H, S, V);
+        }
+    }
+}
diff --git a/src/ThemeEditor.Colors/ThemeEditor.Colors.csproj b/src/ThemeEditor.Colors/ThemeEditor.Colors.csproj
new file mode 100644
index 0000000..2b71fbd
--- /dev/null
+++ b/src/ThemeEditor.Colors/ThemeEditor.Colors.csproj
@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <OutputType>Library</OutputType>
+    <EnableDefaultCompileItems>False</EnableDefaultCompileItems>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <Import Project="..\..\build\Base.props" />
+
+  <ItemGroup>
+    <Compile Include="**\*.cs" Exclude="obj\**" />
+  </ItemGroup>
+
+</Project>
diff --git a/src/ThemeEditor/Controls/ColorPicker.xaml b/src/ThemeEditor/Controls/ColorPicker.xaml
index af5ee57..ed36bc8 100644
--- a/src/ThemeEditor/Controls/ColorPicker.xaml
+++ b/src/ThemeEditor/Controls/ColorPicker.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:local="clr-namespace:ThemeEditor.Controls;assembly=ThemeEditor"
+             xmlns:converters="clr-namespace:ThemeEditor.Converters;assembly=ThemeEditor"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
              mc:Ignorable="d" 
              d:DesignHeight="256" d:DesignWidth="256">
     <UserControl.Resources>
-        <local:HueToColorConverter x:Key="HueToColorConverter"/>
+        <converters:HueToColorConverter x:Key="HueToColorConverter"/>
     </UserControl.Resources>
     <UserControl.Styles>
         <Style Selector="Slider.hue:vertical">
diff --git a/src/ThemeEditor/Controls/ColorPicker.xaml.cs b/src/ThemeEditor/Controls/ColorPicker.xaml.cs
index 2f90528..9630de9 100644
--- a/src/ThemeEditor/Controls/ColorPicker.xaml.cs
+++ b/src/ThemeEditor/Controls/ColorPicker.xaml.cs
@@ -1,165 +1,8 @@
-using System;
-using System.Globalization;
-using Avalonia;
-using Avalonia.Controls;
-using Avalonia.Data.Converters;
+using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
-using Avalonia.Media;
 
 namespace ThemeEditor.Controls
 {
-    public class HSV
-    {
-        public double H { get; set; }
-        public double S { get; set; }
-        public double V { get; set; }
-
-        public HSV()
-        {
-        }
-
-        public HSV(double h, double s, double v)
-        {
-            this.H = h;
-            this.S = s;
-            this.V = v;
-        }
-
-        public HSV(HSV hs)
-        {
-            this.H = hs.H;
-            this.S = hs.S;
-            this.V = hs.V;
-        }
-
-        public HSV(RGB rg)
-        {
-            HSV hs = rg.ToHSV();
-            this.H = hs.H;
-            this.S = hs.S;
-            this.V = hs.V;
-        }
-
-        public RGB ToRGB()
-        {
-            RGB rg = new RGB();
-            HSV hsx = new HSV(this.H, this.S, this.V);
-
-            if (hsx.S == 0)
-            {
-                rg.R = rg.G = rg.B = Math.Round(hsx.V * 2.55); return (rg);
-            }
-
-            hsx.S = hsx.S / 100;
-            hsx.V = hsx.V / 100;
-            hsx.H /= 60;
-
-            var i = Math.Floor(hsx.H);
-            var f = hsx.H - i;
-            var p = hsx.V * (1 - hsx.S);
-            var q = hsx.V * (1 - hsx.S * f);
-            var t = hsx.V * (1 - hsx.S * (1 - f));
-
-            switch ((int)i)
-            {
-                case 0: rg.R = hsx.V; rg.G = t; rg.B = p; break;
-                case 1: rg.R = q; rg.G = hsx.V; rg.B = p; break;
-                case 2: rg.R = p; rg.G = hsx.V; rg.B = t; break;
-                case 3: rg.R = p; rg.G = q; rg.B = hsx.V; break;
-                case 4: rg.R = t; rg.G = p; rg.B = hsx.V; break;
-                default: rg.R = hsx.V; rg.G = p; rg.B = q; break;
-            }
-
-            rg.R = Math.Round(rg.R * 255);
-            rg.G = Math.Round(rg.G * 255);
-            rg.B = Math.Round(rg.B * 255);
-
-            return rg;
-        }
-    }
-
-    public class RGB
-    {
-        public double R { get; set; }
-        public double G { get; set; }
-        public double B { get; set; }
-
-        public RGB()
-        {
-        }
-
-        public RGB(double r, double g, double b)
-        {
-            this.R = r;
-            this.G = g;
-            this.B = b;
-        }
-
-        public RGB(RGB rg)
-        {
-            this.R = rg.R;
-            this.G = rg.G;
-            this.B = rg.B;
-        }
-
-        public RGB(HSV hs)
-        {
-            RGB rg = hs.ToRGB();
-            this.R = rg.R;
-            this.G = rg.G;
-            this.B = rg.B;
-        }
-
-        public HSV ToHSV()
-        {
-            HSV hs = new HSV();
-            RGB rg = new RGB(this.R, this.G, this.B);
-
-            var m = rg.R;
-            if (rg.G < m) { m = rg.G; }
-            if (rg.B < m) { m = rg.B; }
-            var v = rg.R;
-            if (rg.G > v) { v = rg.G; }
-            if (rg.B > v) { v = rg.B; }
-            var value = 100 * v / 255;
-            var delta = v - m;
-            if (v == 0.0) { hs.S = 0; } else { hs.S = 100 * delta / v; }
-
-            if (hs.S == 0) { hs.H = 0; }
-            else
-            {
-                if (rg.R == v) { hs.H = 60.0 * (rg.G - rg.B) / delta; }
-                else if (rg.G == v) { hs.H = 120.0 + 60.0 * (rg.B - rg.R) / delta; }
-                else if (rg.B == v) { hs.H = 240.0 + 60.0 * (rg.R - rg.G) / delta; }
-                if (hs.H < 0.0) { hs.H = hs.H + 360.0; }
-            }
-
-            hs.H = Math.Round(hs.H);
-            hs.S = Math.Round(hs.S);
-            hs.V = Math.Round(value);
-
-            return hs;
-        }
-    }
-
-    public class HueToColorConverter : IValueConverter
-    {
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
-        {
-            if (value is double hue && targetType == typeof(Color))
-            {
-                var rgb = new HSV(hue, 100, 100).ToRGB();
-                var color = new Color(255, (byte)rgb.R, (byte)rgb.G, (byte)rgb.B);
-                return color;
-            }
-            return AvaloniaProperty.UnsetValue;
-        }
-
-        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
-        {
-            throw new NotImplementedException();
-        }
-    }
 
     public class ColorPicker : UserControl
     {
diff --git a/src/ThemeEditor/Converters/HueToColorConverter.cs b/src/ThemeEditor/Converters/HueToColorConverter.cs
new file mode 100644
index 0000000..912e4ad
--- /dev/null
+++ b/src/ThemeEditor/Converters/HueToColorConverter.cs
@@ -0,0 +1,28 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data.Converters;
+using Avalonia.Media;
+using ThemeEditor.Colors;
+
+namespace ThemeEditor.Converters
+{
+    public class HueToColorConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is double hue && targetType == typeof(Color))
+            {
+                var rgb = new HSV(hue, 100, 100).ToRGB();
+                var color = new Color(255, (byte)rgb.R, (byte)rgb.G, (byte)rgb.B);
+                return color;
+            }
+            return AvaloniaProperty.UnsetValue;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}
diff --git a/src/ThemeEditor/ThemeEditor.csproj b/src/ThemeEditor/ThemeEditor.csproj
index e8ab664..5aba62b 100644
--- a/src/ThemeEditor/ThemeEditor.csproj
+++ b/src/ThemeEditor/ThemeEditor.csproj
@@ -22,6 +22,7 @@
   <Import Project="..\..\build\EmbedXaml.props" />
 
   <ItemGroup>
+    <ProjectReference Include="..\ThemeEditor.Colors\ThemeEditor.Colors.csproj" />
     <ProjectReference Include="..\ThemeEditor.ViewModels\ThemeEditor.ViewModels.csproj" />
   </ItemGroup>
 
diff --git a/tests/ThemeEditor.Colors.UnitTests/HSVTests.cs b/tests/ThemeEditor.Colors.UnitTests/HSVTests.cs
new file mode 100644
index 0000000..e3185cf
--- /dev/null
+++ b/tests/ThemeEditor.Colors.UnitTests/HSVTests.cs
@@ -0,0 +1,17 @@
+using Xunit;
+
+namespace ThemeEditor.Colors.UnitTests
+{
+    public class HSVTests
+    {
+        [Fact]
+        public void HSV_ToRGB()
+        {
+            var hsv = new HSV(213.0, 46.0, 49.0);
+            var actual = hsv.ToRGB();
+            Assert.Equal(67.0, actual.R);
+            Assert.Equal(93.0, actual.G);
+            Assert.Equal(125.0, actual.B);
+        }
+    }
+}
diff --git a/tests/ThemeEditor.Colors.UnitTests/RGBTests.cs b/tests/ThemeEditor.Colors.UnitTests/RGBTests.cs
new file mode 100644
index 0000000..aa53752
--- /dev/null
+++ b/tests/ThemeEditor.Colors.UnitTests/RGBTests.cs
@@ -0,0 +1,17 @@
+using Xunit;
+
+namespace ThemeEditor.Colors.UnitTests
+{
+    public class RGBTests
+    {
+        [Fact]
+        public void RGB_ToHSV()
+        {
+            var rgb = new RGB(67.0, 93.0, 125.0);
+            var actual = rgb.ToHSV();
+            Assert.Equal(213.0, actual.H);
+            Assert.Equal(46.0, actual.S);
+            Assert.Equal(49.0, actual.V);
+        }
+    }
+}
diff --git a/tests/ThemeEditor.Colors.UnitTests/ThemeEditor.Colors.UnitTests.csproj b/tests/ThemeEditor.Colors.UnitTests/ThemeEditor.Colors.UnitTests.csproj
new file mode 100644
index 0000000..b88cd63
--- /dev/null
+++ b/tests/ThemeEditor.Colors.UnitTests/ThemeEditor.Colors.UnitTests.csproj
@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>netcoreapp2.1</TargetFrameworks>
+  </PropertyGroup>
+
+  <Import Project="..\..\build\Rx.props" />
+  <Import Project="..\..\build\XUnit.props" />
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\ThemeEditor.Colors\ThemeEditor.Colors.csproj" />
+  </ItemGroup>
+
+</Project>