Demonstrate ICC conversion comparison to Unicolour

tests/ImageSharp.Tests/ImageSharp.Tests.csproj

@@ -32,6 +32,12 @@
       <AutoGen>True</AutoGen>
       <DependentUpon>PixelOperationsTests.Specialized.Generated.tt</DependentUpon>
     </None>
+    <None Update="TestDataIcc\Profiles\Coated_Fogra39L_VIGC_300.icc">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="TestDataIcc\Profiles\SWOP2006_Coated5v2.icc">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 
   <ItemGroup>
@@ -47,6 +53,7 @@
     <PackageReference Include="runtime.osx.10.10-x64.CoreCompat.System.Drawing" Condition="'$(IsOSX)'=='true'" />
     <PackageReference Include="SharpZipLib" />
     <PackageReference Include="System.Drawing.Common" />
+    <PackageReference Include="Wacton.Unicolour" Version="4.7.0" />
   </ItemGroup>
 
   <ItemGroup>
@@ -80,9 +87,5 @@
     <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
   </ItemGroup>
 
-  <ItemGroup>
-    <Folder Include="Colorspaces\" />
-  </ItemGroup>
-
 </Project>
 

tests/ImageSharp.Tests/Metadata/Profiles/ICC/IccProfileTests.cs

@@ -1,8 +1,11 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using SixLabors.ImageSharp.ColorProfiles;
 using SixLabors.ImageSharp.Metadata.Profiles.Icc;
 using SixLabors.ImageSharp.Tests.TestDataIcc;
+using Wacton.Unicolour;
+using Wacton.Unicolour.Icc;
 
 namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.Icc;
 
@@ -40,4 +43,67 @@ public class IccProfileTests
 
         Assert.Equal(expected, result);
     }
+
+    private const string Fogra39 = "Coated_Fogra39L_VIGC_300.icc";
+    private const string Swop2006 = "SWOP2006_Coated5v2.icc";
+
+    [Theory]
+    [InlineData(Fogra39, Fogra39)]
+    [InlineData(Fogra39, Swop2006)]
+    [InlineData(Swop2006, Fogra39)]
+    [InlineData(Swop2006, Swop2006)]
+    public void UnicolourComparison(string sourceProfileName, string targetProfileName)
+    {
+        string sourceIccFilepath = Path.Combine(".", "TestDataIcc", "Profiles", sourceProfileName);
+        string targetIccFilepath = Path.Combine(".", "TestDataIcc", "Profiles", targetProfileName);
+
+        // TODO: pass in specific values to test? use random values?
+        Cmyk input = new(0.8f, 0.6f, 0.4f, 0.2f);
+        Cmyk expectedTargetValues = GetExpectedTargetCmyk(sourceIccFilepath, targetIccFilepath, input);
+
+        ColorProfileConverter converter = new(new ColorConversionOptions
+        {
+            SourceIccProfile = new IccProfile(File.ReadAllBytes(sourceIccFilepath)),
+            TargetIccProfile = new IccProfile(File.ReadAllBytes(targetIccFilepath))
+        });
+
+        Cmyk actualTargetValues = converter.Convert<Cmyk, Cmyk>(input);
+
+        const double tolerance = 0.0000005;
+        Assert.Equal(expectedTargetValues.C, actualTargetValues.C, tolerance);
+        Assert.Equal(expectedTargetValues.M, actualTargetValues.M, tolerance);
+        Assert.Equal(expectedTargetValues.Y, actualTargetValues.Y, tolerance);
+        Assert.Equal(expectedTargetValues.K, actualTargetValues.K, tolerance);
+    }
+
+    private static Cmyk GetExpectedTargetCmyk(string sourceIccFilepath, string targetIccFilepath, Cmyk sourceCmyk)
+    {
+        Wacton.Unicolour.Configuration sourceConfig = GetUnicolourConfig(sourceIccFilepath);
+        Wacton.Unicolour.Configuration targetConfig = GetUnicolourConfig(targetIccFilepath);
+
+        Channels channels = new(sourceCmyk.C, sourceCmyk.M, sourceCmyk.Y, sourceCmyk.K);
+
+        Unicolour source = new(sourceConfig, channels);
+        ColourSpace pcs = sourceConfig.Icc.Profile!.Header.Pcs == "Lab " ? ColourSpace.Lab : ColourSpace.Xyz;
+        ColourTriplet pcsTriplet = pcs == ColourSpace.Lab ? source.Lab.Triplet : source.Xyz.Triplet;
+        Unicolour target = new(targetConfig, pcs, pcsTriplet.Tuple);
+        double[] targetCmyk = target.Icc.Values;
+        return new Cmyk((float)targetCmyk[0], (float)targetCmyk[1], (float)targetCmyk[2], (float)targetCmyk[3]);
+    }
+
+    // Unicolour configurations are relatively expensive to instantiate
+    private static readonly Dictionary<string, Wacton.Unicolour.Configuration> UnicolourConfigCache = new();
+
+    private static Wacton.Unicolour.Configuration GetUnicolourConfig(string iccFilepath)
+    {
+        Wacton.Unicolour.Configuration config;
+        if (UnicolourConfigCache.TryGetValue(iccFilepath, out config))
+        {
+            return config;
+        }
+
+        config = new Wacton.Unicolour.Configuration(iccConfiguration: new(iccFilepath, Intent.Unspecified));
+        UnicolourConfigCache.Add(iccFilepath, config);
+        return config;
+    }
 }