Win8 Metro(C#) 數字圖像處理--1 圖像打開，儲存作為本專欄的第一篇，必不可少的需要介紹一下圖像的打開與儲存，一便大家後面DEMO的制作。

  Win8Metro程式設計中，圖像相關的操作基本都是以流的形式進行的，圖像對象類型在Metro主要表現為兩種形式：BitmapImage和WriteableBitmap，圖像的顯示控件為Image。

  我們可以用如下方式打開和顯示一幅圖像對象。

BitmapImage srcImage=newBitmapImage (new Uri(“UriPath”), UriKind.Relative)

  其中UriPath為圖像的Uri位址，UriKind表示路徑的選擇，Urikind.Relative表示是相對路徑，也可以選擇絕對路徑Urikind.Absolute，或者Urikind.

RelativeOrAbsolute。

Image imageBox=newImage ();

imageBox.Source=srcImage;//将圖像顯示在imageBox控件中

  還有一種方法則是使用WriteableBitmap對象，這也是我這裡要詳細介紹的方法。

        privatestaticBitmapImage srcImage =newBitmapImage();

        privatestaticWriteableBitmap

wbsrcImage;

       //open image fuctiondefinition

        privateasyncvoid

OpenImage()

        {

            FileOpenPicker imagePicker =newFileOpenPicker

            {

ViewMode = PickerViewMode.Thumbnail,

               SuggestedStartLocation =PickerLocationId.PicturesLibrary,

FileTypeFilter = { ".jpg",".jpeg",".png",".bmp"

}

            };

            Guid decoderId;

            StorageFile imageFile =await

imagePicker.PickSingleFileAsync();

            if (imageFile !=null)

srcImage = newBitmapImage();

using (IRandomAccessStream stream =await

imageFile.OpenAsync(FileAccessMode.Read))

{

                   srcImage.SetSource(stream);

switch (imageFile.FileType.ToLower())

                       case".jpg":

                       case".jpeg":

                           decoderId = Windows.Graphics.Imaging.BitmapDecoder.JpegDecoderId;

                           break;

                       case".bmp":

                           decoderId = Windows.Graphics.Imaging.BitmapDecoder.BmpDecoderId;

                       case".png":

                           decoderId = Windows.Graphics.Imaging.BitmapDecoder.PngDecoderId;

                       default:

         return;

                   Windows.Graphics.Imaging.BitmapDecoder decoder =await

Windows.Graphics.Imaging.BitmapDecoder.CreateAsync(decoderId, stream);

int width = (int)decoder.PixelWidth;

      int height = (int)decoder.PixelHeight;

                   Windows.Graphics.Imaging.PixelDataProvider dataprovider =await

decoder.GetPixelDataAsync();

byte[] pixels =dataprovider.DetachPixelData();

wbsrcImage = newWriteableBitmap(width, height);

Stream pixelStream =wbsrcImage.PixelBuffer.AsStream();

//rgba in original  

//to display ,convert tobgra  

for (int i = 0; i < pixels.Length; i += 4)

                       byte temp = pixels[i];

                       pixels[i] =pixels[i + 2];

                       pixels[i +2] = temp;

                   pixelStream.Write(pixels, 0, pixels.Length);

                   pixelStream.Dispose();

                   stream.Dispose();

ImageOne.Source =wbsrcImage;

ImageOne.Width =wbsrcImage.PixelWidth;

ImageOne.Height =wbsrcImage.PixelHeight;

            }

        }

//save image fuction definition

SaveImage(WriteableBitmap src)

            FileSavePicker save =newFileSavePicker();

           save.SuggestedStartLocation =PickerLocationId.PicturesLibrary;

           save.DefaultFileExtension =".jpg";

            save.SuggestedFileName ="newimage";

           save.FileTypeChoices.Add(".bmp",newList<string>()

{ ".bmp" });

           save.FileTypeChoices.Add(".png",newList<string>()

{ ".png" });

           save.FileTypeChoices.Add(".jpg",newList<string>()

{ ".jpg",".jpeg" });

            StorageFile savedItem =await

save.PickSaveFileAsync();

            try

Guid encoderId;

switch (savedItem.FileType.ToLower())

case".jpg":

                       encoderId =BitmapEncoder.JpegEncoderId;

                       break;

case".bmp":

                       encoderId =BitmapEncoder.BmpEncoderId;

case".png":

default:

                       encoderId =BitmapEncoder.PngEncoderId;

IRandomAccessStream fileStream =await savedItem.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

BitmapEncoder encoder =awaitBitmapEncoder.CreateAsync(encoderId,

fileStream);

Stream pixelStream =src.PixelBuffer.AsStream();

                byte[] pixels =newbyte[pixelStream.Length];

               pixelStream.Read(pixels, 0, pixels.Length);

//pixal format shouldconvert to rgba8

                    byte temp = pixels[i];

pixels[i] =pixels[i + 2];

pixels[i + 2] =temp;

               encoder.SetPixelData(

BitmapPixelFormat.Rgba8,

BitmapAlphaMode.Straight,

(uint)src.PixelWidth,

(uint)src.PixelHeight,

96, // Horizontal DPI

96, // Vertical DPI

pixels

);

await encoder.FlushAsync();

            }

            catch (Exception

e)

throw e;

最後，分享一個專業的圖像處理網站（微像素），裡面有很多源代碼下載下傳：

<a href="http://www.zealpixel.com/portal.php">http://www.zealpixel.com/portal.php</a>