作为第一篇文章，本人将介绍Instagram中Brannan 滤镜的实现过程，当然，是自己的模拟而已，结果差异敬请谅解。

    先看下效果图：

1 PS实现步骤：

1.1 打开测试图像，复制图层，命名为图层a；

1.2 对图层a进行去色操作，然后，打开色阶-绿色-调整如下：

1.3对当前图层a选择图层混合模式-滤色；

1.4新建图层b，填充颜色RGB(36,1, 34)，选择图层混合模式-柔光，不透明度60%：

1.5新建图层c，填充颜色RGB(253,253,241)，选择图层混合模式-正片叠底：

1.6合并所有图层，即可得到相应的效果图了；

2，程序实现：

<span style="font-size:14px;">public static Bitmap DoGrayEffect(Bitmap srcBitmap, int pxMode)

{

    Bitmap src = new Bitmap(srcBitmap);

    int w = src.Width;

    int h = src.Height;

    PixelFormat format = (pxMode == 0 ? PixelFormat.Format24bppRgb : PixelFormat.Format32bppArgb);

    BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, format);

    Desaturate((byte*)srcData.Scan0, w, h, srcData.Stride, pxMode);

    src.UnlockBits(srcData);

    return src;

}</span>

<span style="font-size:14px;"> //色阶调整

public static Bitmap DoLevelAdjust(Bitmap srcBitmap, int DestChannel, int InputLeftLimit, int InputMiddle, int InputRightLimit, int OutputLeftLimit, int OutputRightLimit, int pxMode)

{

    Bitmap src = new Bitmap(srcBitmap);

    int w = src.Width;

    int h = src.Height;

    PixelFormat format = (pxMode == 0 ? PixelFormat.Format24bppRgb : PixelFormat.Format32bppArgb);

    BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, format);

    LevelAdjust((byte*)srcData.Scan0, w, h, srcData.Stride, DestChannel, InputLeftLimit, InputMiddle, InputRightLimit, OutputLeftLimit, OutputRightLimit, pxMode);

    src.UnlockBits(srcData);

    return src;

}</span>

<span style="font-size:14px;">//图层混合模式

        public static Bitmap DoEffect(Bitmap srcBitmap, Bitmap mxBitmap, int pxMode, int effectMode)

        {

            Bitmap src = new Bitmap(srcBitmap);

            Bitmap mx = new Bitmap(mxBitmap);

            int w = src.Width;

            int h = src.Height;

            PixelFormat format = (pxMode == 0 ? PixelFormat.Format24bppRgb : PixelFormat.Format32bppArgb);

            BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, format);

            BitmapData mxData = mx.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, format);

            DoSpecialEffect((byte*)srcData.Scan0, (byte*)mxData.Scan0, w, h, srcData.Stride, pxMode, effectMode);

            src.UnlockBits(srcData);

            mx.UnlockBits(mxData);

            return src;

        }

        //单色图层混合模式

        public static Bitmap DoSingleColorEffect(Bitmap srcBitmap, int r, int g, int b, int pxMode, int effectMode)

        {

            Bitmap src = new Bitmap(srcBitmap);

            int w = src.Width;

            int h = src.Height;

            PixelFormat format = (pxMode == 0 ? PixelFormat.Format24bppRgb : PixelFormat.Format32bppArgb);

            BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, format);

            byte* p = (byte*)srcData.Scan0;

            int seg = (pxMode == 0 ? 3 : 4);

            for (int y = 0; y < h; y++)

            {

                for (int x = 0; x < w; x++)

                {

                    DoPixelEffect(p, r, g, b, effectMode);

                    p += seg;

                }

                p += srcData.Stride - w * seg;

            }

            src.UnlockBits(srcData);

            return src;

        }</span>

<span style="font-size:14px;">        //Brannan 滤镜

        public static Bitmap BrannanFilter(Bitmap srcBitmap, int pxMode)

        {

            Bitmap temp = DoGrayEffect(srcBitmap, 0);//去色

            Bitmap leBmp = DoLevelAdjust(temp, 2, 0, 128, 232, 0, 250, 0);//绿色色阶调整

            Bitmap filterBmp = DoEffect(srcBitmap, leBmp, 0, (int)EffectMode.MODE_FILTERCOLOR);//滤色

            temp = DoSingleColorEffect(filterBmp, 22, 1, 20, 0, (int)EffectMode.MODE_SMOOTHLIGHT);//柔化

            temp = DoSingleColorEffect(temp, 253, 253, 241, 0, (int)EffectMode.MODE_MULTIPLY);//正片叠底

            return temp;

        }</span>

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