刚刚做过这类开发，所以就先献丑了，当然所贴上的源代码都是经过验证过的，已经执行成功了，希望能够给大家一些借鉴：

以下是metro UI代码：

<Page
    x:Class="Camera.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Camera"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <Button x:Name="btnCamera" Content="打开摄像头" HorizontalAlignment="Left" Margin="48,259,0,0" VerticalAlignment="Top" Click="btnCamera_Click" Height="45"/>
        <Image x:Name="img1" HorizontalAlignment="Left" Height="609" Margin="240,78,0,0" VerticalAlignment="Top" Width="718" Stretch="Fill"/>
        <Button x:Name="btnSave" Content="保存图片" HorizontalAlignment="Left" Margin="48,369,0,0" VerticalAlignment="Top" Height="44" Click="btnSave_Click"/>
    </Grid>
</Page>

显示的界面事实上非常easy，可是这不重要，功能才是基本的，以下贴上基本的开发代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using Windows.Media.Capture;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.UI.Xaml.Media.Imaging;
using Windows.Storage.Streams;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

/*
 * 
 * 作者：李天鹏
 * 功能：调用PC上自带的camera实现拍照的功能，并保存在对应的目录下
 * */
namespace Camera
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        private StorageFile file = null;
        public MainPage()
        {
            this.InitializeComponent();

        }

        private async void btnCamera_Click(object sender, RoutedEventArgs e)
        {
            CameraCaptureUI dialog = new CameraCaptureUI();
            dialog.PhotoSettings.CroppedAspectRatio = new Size(16, 9);
            file = await dialog.CaptureFileAsync(CameraCaptureUIMode.Photo);
            if (file != null)
            {
                BitmapImage bitmapImage = new BitmapImage();
                using (IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read))
                {
                    bitmapImage.SetSource(fileStream);
                }
                img1.Source = bitmapImage;
            }
        }

        private async void btnSave_Click(object sender, RoutedEventArgs e)
        {
            if (img1.Source == null)
                return;
            else
            {
                FileSavePicker picker = new FileSavePicker();
                picker.CommitButtonText = "保存";
                picker.SuggestedFileName = "hello";
                picker.FileTypeChoices.Add("图片",new string[]{".jpg",".jpeg",".bmp",".png"});

                picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
                StorageFile filePath = await picker.PickSaveFileAsync();
                if (filePath != null)
                {
                    //打开通过摄像头拍摄的照片，并返回流，以流的形式读取文件
                    var streamRandom = await file.OpenAsync(FileAccessMode.Read);
                    //将拍摄的照片以流的形式读取到缓冲区
                    IBuffer buffer = RandomAccessStreamToBuffer(streamRandom);
                    //将缓冲区内容写入对应的目录中
                    await FileIO.WriteBufferAsync(filePath, buffer);
                }
            }
        }

        //将图片写入到缓冲区
        private IBuffer RandomAccessStreamToBuffer(IRandomAccessStream randomstream)
        {
            Stream stream = WindowsRuntimeStreamExtensions.AsStreamForRead(randomstream.GetInputStreamAt(0));
            MemoryStream memoryStream = new MemoryStream();
            if (stream != null)
            {
                byte[] bytes = ConvertStreamTobyte(stream);  //将流转化为字节型数组
                if (bytes != null)
                {
                    var binaryWriter = new BinaryWriter(memoryStream);
                    binaryWriter.Write(bytes);
                }
            }
            IBuffer buffer = WindowsRuntimeBufferExtensions.GetWindowsRuntimeBuffer(memoryStream, 0, (int)memoryStream.Length);
            return buffer;
        }

        //将流转换成二进制
        public static byte[] ConvertStreamTobyte(Stream input)
        {
            byte[] buffer = new byte[16 * 1024];
            using (MemoryStream ms = new MemoryStream())
            {
                int read;
                while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
                {
                    ms.Write(buffer, 0, read);
                }
                return ms.ToArray();
            }
        }
    }
}

改动例如以下：仅仅要勾上webcam即可了。

源代码下载：

http://download.csdn.net/detail/litianpeng1991/7548065