C# image compare

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;

namespace testsharp
{
    class test12
    {
        static byte[] ImageToBytes(Bitmap bitmap)
        {
            byte[] data = new byte[bitmap.Width * bitmap.Height * 4];
            BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);

            unsafe
            {
                for (int y = 0; y < bitmapData.Height; y++)
                {
                    byte* row = (byte*)bitmapData.Scan0 + (y * bitmapData.Stride);
                    for (int x = 0; x < bitmapData.Width; x++)
                    {
                        data[(y * bitmapData.Width + x) * 4 + 0] = row[x * 4 + 2]; //Internal R
                        data[(y * bitmapData.Width + x) * 4 + 1] = row[x * 4 + 1]; //Internal G
                        data[(y * bitmapData.Width + x) * 4 + 2] = row[x * 4 + 0]; //Internal B
                        data[(y * bitmapData.Width + x) * 4 + 3] = row[x * 4 + 3]; //Internal A
                    }
                }
            }
            bitmap.UnlockBits(bitmapData);

            return data;
        }

        static Bitmap BytesToImage(byte[] data, int width, int height)
        {
            Bitmap bitmap = new Bitmap(width, height);
            BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);

            unsafe
            {
                for (int y = 0; y < bitmapData.Height; y++)
                {
                    byte* row = (byte*)bitmapData.Scan0 + (y * bitmapData.Stride);
                    for (int x = 0; x < bitmapData.Width; x++)
                    {
                        row[x * 4 + 0] = data[(y * bitmapData.Width + x) * 4 + 2]; //Internal B
                        row[x * 4 + 1] = data[(y * bitmapData.Width + x) * 4 + 1]; //Internal G
                        row[x * 4 + 2] = data[(y * bitmapData.Width + x) * 4 + 0]; //Internal R
                        row[x * 4 + 3] = data[(y * bitmapData.Width + x) * 4 + 3]; //Internal A
                    }
                }
            }

            bitmap.UnlockBits(bitmapData);

            return bitmap;
        }

        static byte AdjustBrightness(byte b, float factor)
        {
            return (byte)(Math.Pow((float)b / 255, factor) * 255); // gamma
        }

        static void FindImageDifferences(string pathIn1, string pathIn2, string pathOut)
        {
            Image img1 = Image.FromFile(pathIn1);
            Image img2 = Image.FromFile(pathIn2);

            if (img1.Width != img2.Width || img1.Height != img2.Height)
                return;

            byte[] data1 = ImageToBytes((Bitmap)img1);
            byte[] data2 = ImageToBytes((Bitmap)img2);


            byte[] data3 = new byte[data1.Length];

            for (int i = 0; i < data3.Length; i++)
            {
                int diff = Math.Abs(data1[i] - data2[i]);
                if (diff < 40)
                    diff = 0;
                diff *= 20;
                int newValue = diff + AdjustBrightness(data1[i], 1.6f);
                if (newValue > 255)
                    data3[i] = 255;
                else
                    data3[i] = (byte)newValue;
            }
            Image imgOut = BytesToImage(data3, img1.Width, img1.Height);
            imgOut.Save(pathOut, ImageFormat.Png);

            img1.Dispose();
            img2.Dispose();
            imgOut.Dispose();
        }

        public static void Main()
        {
            string pathIn1 = @"e:\temp\i1.png";
            string pathIn2 = @"e:\temp\i2.png";
            string pathOut = @"e:\temp\out.png";

            FindImageDifferences(pathIn1, pathIn2, pathOut);
        }

    }
}