.NET 图片像素比较

        /// <summary>
        /// 图像比较.用于找出两副图片之间的差异位置
        /// </summary>
        public class ImageComparer
        {
            /// <summary>
            /// 图像颜色
            /// </summary>
            [StructLayout(LayoutKind.Explicit)]
            private struct ICColor
            {
                [FieldOffset(0)]
                public byte B;
                [FieldOffset(1)]
                public byte G;
                [FieldOffset(2)]
                public byte R;
            }

            /// <summary>
            /// 按20*20大小进行分块比较两个图像.
            /// </summary>
            /// <param name="bmp1"></param>
            /// <param name="bmp2"></param>
            /// <returns></returns>
            public static List<Rectangle> Compare(Bitmap bmp1, Bitmap bmp2)
            {
                return Compare(bmp1, bmp2, new Size(20, 20));
            }
            /// <summary>
            /// 比较两个图像
            /// </summary>
            /// <param name="bmp1"></param>
            /// <param name="bmp2"></param>
            /// <param name="block"></param>
            /// <returns></returns>
            public static List<Rectangle> Compare(Bitmap bmp1, Bitmap bmp2, Size block)
            {
                List<Rectangle> rects = new List<Rectangle>();
                PixelFormat pf = PixelFormat.Format24bppRgb;

                BitmapData bd1 = bmp1.LockBits(new Rectangle(0, 0, bmp1.Width, bmp1.Height), ImageLockMode.ReadOnly, pf);
                BitmapData bd2 = bmp2.LockBits(new Rectangle(0, 0, bmp2.Width, bmp2.Height), ImageLockMode.ReadOnly, pf);

                try
                {
                    unsafe
                    {
                        int w = 0, h = 0;

                        while (h < bd1.Height && h < bd2.Height)
                        {
                            byte* p1 = (byte*)bd1.Scan0 + h * bd1.Stride;
                            byte* p2 = (byte*)bd2.Scan0 + h * bd2.Stride;

                            w = 0;
                            while (w < bd1.Width && w < bd2.Width)
                            {
                                //按块大小进行扫描
                                for (int i = 0; i < block.Width; i++)
                                {
                                    int wi = w + i;
                                    if (wi >= bd1.Width || wi >= bd2.Width) break;

                                    for (int j = 0; j < block.Height; j++)
                                    {
                                        int hj = h + j;
                                        if (hj >= bd1.Height || hj >= bd2.Height) break;

                                        ICColor* pc1 = (ICColor*)(p1 + wi * 3 + bd1.Stride * j);
                                        ICColor* pc2 = (ICColor*)(p2 + wi * 3 + bd2.Stride * j);
                                        // if (Math.Abs(pc1->R - pc2->R)>10 || pc1->G != pc2->G || pc1->B != pc2->B)
                                        if (Math.Abs(pc1->R - pc2->R) > 100 || Math.Abs(pc1->G - pc2->G) > 100 || Math.Abs(pc1->B - pc2->B) > 100)
                                        {
                                            //当前块有某个象素点颜色值不相同.也就是有差异.

                                            int bw = Math.Min(block.Width, bd1.Width - w);
                                            int bh = Math.Min(block.Height, bd1.Height - h);
                                            rects.Add(new Rectangle(w, h, bw, bh));

                                            goto E;
                                        }
                                    }
                                }
                            E:
                                w += block.Width;
                            }

                            h += block.Height;
                        }
                    }
                }
                finally
                {
                    bmp1.UnlockBits(bd1);
                    bmp2.UnlockBits(bd2);
                }

                return rects;
            }
        }