WPF 调节图片的明度(亮度)

void SetBrightness(int brightness)
        {
            brightness = brightness * 255 / 100;

            WriteableBitmap wb = new WriteableBitmap(this.ImgViewBak.Source as BitmapSource);
            uint[] PixelData = new uint[wb.PixelWidth * wb.PixelHeight];
            wb.CopyPixels(PixelData, 4 * wb.PixelWidth, 0);
            for (uint y = 0; y < wb.PixelHeight; y++)
            {
                for (uint x = 0; x < wb.PixelWidth; x++)
                {
                    uint pixel = PixelData[y * wb.PixelWidth + x];
                    byte[] dd = BitConverter.GetBytes(pixel);
                    int B = (int)dd[0] + brightness;
                    int G = (int)dd[1] + brightness;
                    int R = (int)dd[2] + brightness;
                    if (B < 0) B = 0;
                    if (B > 255) B = 255;
                    if (G < 0) G = 0;
                    if (G > 255) G = 255;
                    if (R < 0) R = 0;
                    if (R > 255) R = 255;
                    dd[0] = (byte)B;
                    dd[1] = (byte)G;
                    dd[2] = (byte)R;
                    PixelData[y * wb.PixelWidth + x] = BitConverter.ToUInt32(dd, 0);
                }
            }
            wb.WritePixels(new Int32Rect(0, 0, wb.PixelWidth, wb.PixelHeight), PixelData, 4 * wb.PixelWidth, 0);
            this.ImgView.Source = wb;
        }