AutoStereogramDemo.AutoStereogramBuilder.SampleImageColorGenerator C# (CSharp) Method

        private void SampleImageColorGenerator(Bitmap bitmap, Bitmap backgroundImage, int y, int uniqueColorsCount, int[] colors)
        {
            Color?[] bitmapColors = new Color?[uniqueColorsCount];
            int nextXWithColor = -1;

            for (int x = 0; x < colors.Length; x++)
            {
                if (bitmapColors[colors[x]] == null)
                {
                    if (nextXWithColor < x)
                    {
                        for (int n = 1; n <= SubpixelsCount * 5; n++)
                            if (x + n < XResolutionInternal && bitmapColors[colors[x + n]] != null)
                            {
                                nextXWithColor = x + n;
                                break;
                            }
                    }

                    Color currentColor;
                    if (y % backgroundImage.Height < 5 && y / backgroundImage.Height != 0)
                    {
                        Color c1 = backgroundImage.GetPixel((x / SubpixelsCount) % backgroundImage.Width, backgroundImage.Height - 1);
                        Color c2 = backgroundImage.GetPixel((x / SubpixelsCount) % backgroundImage.Width, y % backgroundImage.Height);
                        double q = (y % backgroundImage.Height + 1) / 6.0;
                        currentColor = Color.FromArgb((int)Math.Round(c1.R * (1 - q) + c2.R * q), (int)Math.Round(c1.G * (1 - q) + c2.G * q), (int)Math.Round(c1.B * (1 - q) + c2.B * q));
                    }
                    else
                        currentColor = backgroundImage.GetPixel((x / SubpixelsCount) % backgroundImage.Width, y % backgroundImage.Height);

                    if (nextXWithColor > x)
                    {
                        Color nextColor = bitmapColors[colors[nextXWithColor]].Value;
                        double q = (double)(nextXWithColor - x) / (SubpixelsCount * 5 + 1);
                        bitmapColors[colors[x]] = Color.FromArgb((int)Math.Round(currentColor.R * q + nextColor.R * (1 - q)), (int)Math.Round(currentColor.G * q + nextColor.G * (1 - q)),
                         (int)Math.Round(currentColor.B * q + nextColor.B * (1 - q)));
                    }
                    else
                        bitmapColors[colors[x]] = currentColor;
                }

                if (x % SubpixelsCount == SubpixelsCount - 1)
                {
                    int r = 0, g = 0, b = 0;
                    for (int n = 0; n < SubpixelsCount; n++)
                    {
                        r += bitmapColors[colors[x - x % SubpixelsCount + n]].Value.R;
                        g += bitmapColors[colors[x - x % SubpixelsCount + n]].Value.G;
                        b += bitmapColors[colors[x - x % SubpixelsCount + n]].Value.B;
                    }

                    Color color = Color.FromArgb((int)Math.Round((double)r / SubpixelsCount), (int)Math.Round((double)g / SubpixelsCount), (int)Math.Round((double)b / SubpixelsCount));
                    bitmap.SetPixel(x / SubpixelsCount, y, color);
                }
            }
        }