我的缩略图生成成功了，但是为什么比大图模糊呢？快来救救我？

Question

HttpPostedFile fpicture=UpFile.PostedFile;
int fpicturelength=fpicture.ContentLength;//文件大小
string fileType = fpicture.ContentType.ToString(); byte []pictureArray=new byte[fpicturelength];
Stream photoStream=fpicture.InputStream;
string strFileName=fpicture.FileName;
string fileName1=strFileName.Substring(strFileName.LastIndexOf("\\"));
int len=fileName1.Length;
string fileName=fileName1.Substring(1,len-1);//整个文件名
int len2 = fileName.Length;
string Extension = fileName.Substring(fileName.LastIndexOf("."));//如 .gif 扩展名
string newFileName = Guid.NewGuid().ToString();
UpFile.PostedFile.SaveAs(Server.MapPath("/Admin/images_Product/")+newFileName+Extension);
//生成缩略图
System.Drawing.Image image, aNewImage;
System.Drawing.Image.GetThumbnailImageAbort callb;
image = System.Drawing.Image.FromStream(photoStream);
image = System.Drawing.Image.FromFile(Server.MapPath("/Admin/images_Product/")+newFileName+Extension);
callb =new System.Drawing .Image.GetThumbnailImageAbort(ThumbnailCallback);
aNewImage=image.GetThumbnailImage(130, 150, callb, new System.IntPtr());
aNewImage.Save(Server.MapPath("/Admin/images_Product_thumb/")+fileName, GetImageType(fileType));public bool ThumbnailCallback()
{
return false;
} private System.Drawing.Imaging.ImageFormat GetImageType(string strContentType) 
{ 
if ((strContentType.ToString().ToLower()) == "image/pjpeg") 
{ 
return System.Drawing.Imaging.ImageFormat.Jpeg; 
} 
else if ((strContentType.ToString().ToLower()) == "image/gif") 
{ 
return System.Drawing.Imaging.ImageFormat.Gif; 
} 
else if ((strContentType.ToString().ToLower()) == "image/bmp") 
{ 
return System.Drawing.Imaging.ImageFormat.Bmp; 
} 
else if ((strContentType.ToString().ToLower()) == "image/tiff") 
{ 
return System.Drawing.Imaging.ImageFormat.Tiff; 
} 
else if ((strContentType.ToString().ToLower()) == "image/x-icon") 
{ 
return System.Drawing.Imaging.ImageFormat.Icon; 
} 
else if ((strContentType.ToString().ToLower()) == "image/x-png") 
{ 
return System.Drawing.Imaging.ImageFormat.Png; 
} 
else if ((strContentType.ToString().ToLower()) == "image/x-emf") 
{ 
return System.Drawing.Imaging.ImageFormat.Emf; 
} 
else if ((strContentType.ToString().ToLower()) == "image/x-exif") 
{ 
return System.Drawing.Imaging.ImageFormat.Exif; 
} 
else if ((strContentType.ToString().ToLower()) == "image/x-wmf") 
{ 
return System.Drawing.Imaging.ImageFormat.Wmf; 
} 
else 
{ 
return System.Drawing.Imaging.ImageFormat.MemoryBmp; 
} 
}