AnimalCrossingQR.AC.Pattern.CalculateLeastImportantColor C# (CSharp) Method

        private Color CalculateLeastImportantColor(Color[,] image, HashSet<Color> palette)
        {
            Dictionary<Color, double> colorErrorSquaredDelta = new Dictionary<Color, double>();
            foreach (Color c in palette)
                colorErrorSquaredDelta.Add(c, 0);

            for (int i = 0; i < image.GetLength(0); i++)
                for (int j = 0; j < image.GetLength(1); j++)
                {
                    Color nearestColor = GetNearestColor(palette, image[i, j]);

                    double currentError = Color.DistanceSquared(image[i, j], nearestColor);
                    double potentialError = Color.DistanceSquared(image[i, j], GetSecondNearestColor(palette, image[i, j]));

                    colorErrorSquaredDelta[nearestColor] += (potentialError - currentError);
                }

            return colorErrorSquaredDelta.Aggregate((a, b) => (a.Value < b.Value) ? a : b).Key;
        }