Colorizer Class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Threading.Tasks;
using System.Threading;

namespace ImatgesIColoraines
{
    public delegate void ActualizarProgress();

    public enum Estil
    { EscalaDeGrisos, Sepia, Vermell, Verd, Blau, Invers }

    struct Pixel
    {
        public byte red;
        public byte green;
        public byte blue;
    }

    public static class Colorizer
    {
        public static event ActualizarProgress UpdProg;

        public static Bitmap ChangeColor(Bitmap img, Estil estil)
        {
            int y = 0, x = 0;
            Pixel original;
            Color cambiat = new Color();
            Bitmap nImg =(Bitmap) img.Clone();

            while (y < img.Height)
            {

                original = GetPixel(img, x, y);
                switch (estil)
                {
                    case Estil.EscalaDeGrisos:
                        cambiat =  BlackWhite(GetPixel(img, x, y));
                        break;
                    case Estil.Invers:
                        cambiat = Inverter(GetPixel(img, x, y));
                        break;
                    case Estil.Sepia:
                        cambiat = Sepia(GetPixel(img, x, y));
                        break;
                    case Estil.Vermell:
                        cambiat = RedAxe(GetPixel(img, x, y));
                        break;
                    case Estil.Verd:
                        cambiat = GreenForest(GetPixel(img, x, y));
                        break;
                    case Estil.Blau:
                        cambiat = BlueStar(GetPixel(img, x, y));
                        break;
                }

                nImg.SetPixel(x, y, cambiat);

                x++; //y++;
                if (x >= img.Width)
                {
                    x = 0;
                    y++;
                    if (UpdProg != null && y % 3 == 0)
                        UpdProg();
                }

            }

            return nImg;
        }

        private static Pixel GetPixel(Bitmap img, int x, int y)
        {
            Pixel pix;
            pix.red = img.GetPixel(x, y).R;
            pix.green = img.GetPixel(x, y).G;
            pix.blue = img.GetPixel(x, y).B;

            return pix;
        }

        private static Color BlackWhite(Pixel pix)
        {
            byte resultat = Convert.ToByte((pix.red + pix.green + pix.blue) / 3);

            return Color.FromArgb(255,resultat,resultat,resultat);
        }

        private static Color Inverter(Pixel pix)
        {
            pix.red = (byte) (255 - pix.red);
            pix.green = (byte)(255 - pix.green);
            pix.blue = (byte)(255 - pix.blue);

            return Color.FromArgb(255, pix.red, pix.green, pix.blue);
        }

        private static Color Sepia(Pixel pix)
        {
            double pixelColor;
            pixelColor = (pix.red * .393) + (pix.green * .769) + (pix.blue * .189);
            pix.red = Convert.ToByte(pixelColor > 255 ? 255 : pixelColor);
            pixelColor = (pix.red * .349) + (pix.green * .686) + (pix.blue * .168);
            pix.green = Convert.ToByte(pixelColor > 255 ? 255 : pixelColor);
            pixelColor = (pix.red * .272) + (pix.green * .534) + (pix.blue * .131);
            pix.blue = Convert.ToByte(pixelColor > 255 ? 255 : pixelColor);

            return Color.FromArgb(255, pix.red, pix.green, pix.blue);
        }

        private static Color RedAxe(Pixel pix)
        {
            pix.green = (byte)0;
            pix.blue = (byte)0;

            return Color.FromArgb(255, pix.red, pix.green, pix.blue);
        }

        private static Color GreenForest(Pixel pix)
        {
            pix.red = (byte)0;
            pix.blue = (byte)0;

            return Color.FromArgb(255, pix.red, pix.green, pix.blue);
        }

        private static Color BlueStar(Pixel pix)
        {
            pix.red = (byte)0;
            pix.green = (byte)0;

            return Color.FromArgb(255, pix.red, pix.green, pix.blue);
        }
    }
}