Improve color accuracy in extended appearance

Anamnesis/App.xaml

@@ -37,6 +37,7 @@
 			<BooleanToVisibilityConverter x:Key="B2V" />
 			<converters:Vector2DRadiansToDegreesConverter x:Key="Vec2DRad2Deg" />
 			<converters:ImageReferenceConverter x:Key="Img" />
+			<converters:SquaredRgbConverter x:Key="SquaredRgb" />
 
 			<!--  Atkinson-Hyperlegible font  -->
 			<FontFamily x:Key="Atkinson-Hyperlegible">pack://application:,,,/Assets/Fonts/#Atkinson Hyperlegible</FontFamily>

Anamnesis/Styles/Converters/SquaredRgbConverter.cs

@@ -0,0 +1,46 @@
+// © Anamnesis.
+// Licensed under the MIT license.
+
+namespace Anamnesis.Styles.Converters;
+
+using System;
+using System.Globalization;
+using System.Windows.Data;
+using Anamnesis.Memory;
+
+[ValueConversion(typeof(Color), typeof(Color))]
+[ValueConversion(typeof(Color4), typeof(Color4))]
+public class SquaredRgbConverter : IValueConverter
+{
+	public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+	{
+		if (value is Color rgb)
+		{
+			return new Color(MathF.Sqrt(rgb.R), MathF.Sqrt(rgb.G), MathF.Sqrt(rgb.B));
+		}
+		else if (value is Color4 rgba)
+		{
+			return new Color4(MathF.Sqrt(rgba.R), MathF.Sqrt(rgba.G), MathF.Sqrt(rgba.B), rgba.A);
+		}
+		else
+		{
+			return value;
+		}
+	}
+
+	public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+	{
+		if (value is Color rgb)
+		{
+			return new Color(rgb.R * rgb.R, rgb.G * rgb.G, rgb.B * rgb.B);
+		}
+		else if (value is Color4 rgba)
+		{
+			return new Color4(rgba.R * rgba.R, rgba.G * rgba.G, rgba.B * rgba.B, rgba.A);
+		}
+		else
+		{
+			return value;
+		}
+	}
+}