uwp 图像处理例子

    async  void test() {

            Color replaceBlack = Color.FromArgb(224,233,55,6);
            Color replaceWhite = Color.FromArgb(224, 233, 222, 222);
           // BitmapImage bmpimg = new BitmapImage();

           WriteableBitmap source = this.imageSource1.Source as WriteableBitmap; //need make sure the .imageSource1.Source is  WriteableBitmap

            byte[] byteArray = null;
            using (Stream stream = source.PixelBuffer.AsStream())
            {
                long streamLength = stream.Length;
                byteArray = new byte[streamLength];
                await stream.ReadAsync(byteArray, 0, byteArray.Length);
                if (streamLength > 0)
                {
                    for (int i = 0; i < streamLength; i += 4)
                    {
                        if (byteArray[i + 3] != 0)
                        {
                            int b = Convert.ToInt32(byteArray[i]);
                            int g = Convert.ToInt32(byteArray[i + 1]);
                            int r = Convert.ToInt32(byteArray[i + 2]);

                            int rB = ((((b * replaceBlack.B) / 255) + (((255 - b) * replaceWhite.B) / 255)) / 2);
                            int rG = ((((g * replaceBlack.G) / 255) + (((255 - g) * replaceWhite.G) / 255)) / 2);
                            int rR = ((((r * replaceBlack.R) / 255) + (((255 - r) * replaceWhite.R) / 255)) / 2);

                            byte blue = Convert.ToByte(rB);
                            byte green = Convert.ToByte(rG);
                            byte red = Convert.ToByte(rR);

                            byteArray[i] = blue; // Blue
                            byteArray[i + 1] = green;  // Green
                            byteArray[i + 2] = red; // Red
                        }
                    }
                }
            }
            if (byteArray != null)
            {

                int lw, lh;
                lw = source.PixelWidth;
                lh = source.PixelHeight;
                WriteableBitmap wbbitmap = new WriteableBitmap(source.PixelWidth, source.PixelHeight);
                Stream s = wbbitmap.PixelBuffer.AsStream();
                s.Seek(0, SeekOrigin.Begin);

                s.Write(byteArray, 0, lw * lh * 3);
                s.Flush();

                this.imageTarget2.Source = null;
                this.imageTarget2.Source = wbbitmap;

            }

        }