/// <summary> 

	/// 生成jpg缩略图字节,本人的小软件中需要用到的功能，所以自己做了一个函数，和大家分享 

	/// 为什么要生成字节而不是文件，这是为了方便后续处理啦^_^ 

	/// </summary> 

	/// <param name="originalImagePath">原始路径</param> 

	/// <param name="quality">质量0-100</param> 

	/// <param name="width">宽度</param> 

	/// <param name="height">高度</param> 

	/// <param name="mode">模式：HW,W,H,Cut</param> 

	/// <returns></returns> 

	public static byte[] MakeJPGThumbnailBytes(string originalImagePath, long quality, int width, int height, string mode) 

	{ 

	Image originalImage = Image.FromFile(originalImagePath); 

	MemoryStream s = new MemoryStream(); 

	int towidth = width; 

	int toheight = height; 

	 

	int x = 0; 

	int y = 0; 

	int ow = originalImage.Width; 

	int oh = originalImage.Height; 

	 

	switch (mode) 

	{ 

	case "HW"://指定高宽缩放（可能变形） 

	break; 

	case "W"://指定宽，高按比例 

	toheight = originalImage.Height * width / originalImage.Width; 

	break; 

	case "H"://指定高，宽按比例 

	towidth = originalImage.Width * height / originalImage.Height; 

	break; 

	case "Cut"://指定高宽裁减（不变形） 

	if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) 

	{ 

	oh = originalImage.Height; 

	ow = originalImage.Height * towidth / toheight; 

	y = 0; 

	x = (originalImage.Width - ow) / 2; 

	} 

	else 

	{ 

	ow = originalImage.Width; 

	oh = originalImage.Width * height / towidth; 

	x = 0; 

	y = (originalImage.Height - oh) / 2; 

	} 

	break; 

	default: 

	break; 

	} 

	 

	//新建一个bmp图片 

	Image bitmap = new System.Drawing.Bitmap(towidth, toheight); 

	 

	//新建一个画板 

	Graphics g = System.Drawing.Graphics.FromImage(bitmap); 

	 

	//设置高质量插值法 

	g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; 

	 

	//设置高质量,低速度呈现平滑程度 

	g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 

	 

	//清空画布并以透明背景色填充 

	g.Clear(Color.Transparent); 

	 

	//在指定位置并且按指定大小绘制原图片的指定部分 

	g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight), 

	new Rectangle(x, y, ow, oh), 

	GraphicsUnit.Pixel); 

	 

	try 

	{ 

	//以jpg格式保存缩略图 

	EncoderParameters eps = new EncoderParameters(1); 

	EncoderParameter ep = new EncoderParameter(Encoder.Quality,quality); 

	eps.Param[0] = ep; 

	bitmap.Save(s, GetCodecInfo("image/jpeg"), eps); 

	return s.GetBuffer(); 

	} 

	catch (System.Exception e) 

	{ 

	throw e; 

	} 

	finally 

	{ 

	originalImage.Dispose(); 

	bitmap.Dispose(); 

	s.Dispose(); 

	g.Dispose(); 

	} 

	} 

	 

	/**/ 

	/// <summary> 

	/// 保存JPG时用 

	/// </summary> 

	/// <param name="mimeType"></param> 

	/// <returns>得到指定mimeType的ImageCodecInfo</returns> 

	private static ImageCodecInfo GetCodecInfo(string mimeType) 

	{ 

	ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders(); 

	foreach (ImageCodecInfo ici in CodecInfo) 

	{ 

	if (ici.MimeType == mimeType) return ici; 

	} 

	return null; 

	}