MahApps icon to Image converter

IconConverter.cs

using System;
using System.Globalization;
using System.Windows.Data;
using System.Windows.Media;
using MahApps.Metro.IconPacks;

namespace SomeNamespace
{
    public class IconConverter : IValueConverter
    {
        private const PackIconFontAwesomeKind OkState = PackIconFontAwesomeKind.QuestionCircle;
        private const PackIconFontAwesomeKind MissingState = PackIconFontAwesomeKind.CircleOutline;
        
        private static readonly Brush OkStateBrush = Brushes.DarkGreen;
        private static readonly Brush MissingStateBrush = Brushes.DarkRed;

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var state = value as bool? ?? false;
            return GetIconForState(state);
        }

        private ImageSource GetIconForState(bool state)
        {
            var packIcon = new PackIconFontAwesome()
            {
                Kind = state ? OkState : MissingState
            };

            var brush = state ? OkStateBrush : MissingStateBrush;

            var geometryDrawing = new GeometryDrawing
            {
                Geometry = Geometry.Parse(packIcon.Data),
                Brush = brush,
                Pen = new Pen(brush, 0.25),
            };

            var drawingGroup = new DrawingGroup
            {
                Children = {geometryDrawing},
                Transform = new ScaleTransform(1, -1)
            };

            return new DrawingImage { Drawing = drawingGroup };

        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}