1. Image.FromFile()返回的是某个继承自Image的具体类的对象，在这里，就是Bitmap或者Metafile其中之一。这应该算是factory pattern的一种形式。所以，Image类确实不能直接创建对象的，但这里Image.FromFile()返回的是Bitmap或者Metafile的对象。
2. Bitmap不仅仅对应于bmp，其实只要是像素式的图片格式（矢量格式不行），理论上都可以用Bitmap，就像YJPC789(雪地里的一颗星) 所说的。Image所抽象的是Bitmap和Metafile两个子类，你可以看一下msdn里的介绍。
////// 将图片Image转换成Byte[]/// /// image对象/// 后缀名///public static byte[] ImageToBytes(Image Image, System.Drawing.Imaging.ImageFormat imageFormat){ if (Image == null) { return null; } byte[] data = http://www.cnblogs.com/peasana/archive/2012/02/13/null; using (MemoryStream ms= new MemoryStream()) { using (Bitmap Bitmap = new Bitmap(Image)) { Bitmap.Save(ms, imageFormat); ms.Position = 0; data = http://www.cnblogs.com/peasana/archive/2012/02/13/new byte[ms.Length]; ms.Read(data, 0, Convert.ToInt32(ms.Length)); ms.Flush(); } } return data;} /// /// byte[]转换成Image/// /// 二进制图片流///Image public static System.Drawing.Image byteArrayToImage(byte[] byteArrayIn){ if (byteArrayIn == null) return null; using (System.IO.MemoryStream ms = new System.IO.MemoryStream(byteArrayIn)) { System.Drawing.Image returnImage = System.Drawing.Image.FromStream(ms); ms.Flush(); return returnImage; }}//Image转换Bitmap1. Bitmap img = new Bitmap(imgSelect.Image);2. Bitmap bmp = (Bitmap)pictureBox1.Image;//Bitmap转换成Imageusing System.IO;private static System.Windows.Controls.Image Bitmap2Image(System.Drawing.Bitmap Bi){ MemoryStream ms = new MemoryStream(); Bi.Save(ms, System.Drawing.Imaging.ImageFormat.Png); BitmapImage bImage = new BitmapImage(); bImage.BeginInit(); bImage.StreamSource = new MemoryStream(ms.ToArray()); bImage.EndInit(); ms.Dispose(); Bi.Dispose(); System.Windows.Controls.Image i = new System.Windows.Controls.Image(); i.Source = bImage; return i ;}//byte[] 转换 Bitmappublic static Bitmap BytesToBitmap(byte[] Bytes) { MemoryStream stream = null; try { stream = new MemoryStream(Bytes); return new Bitmap((Image)new Bitmap(stream)); } catch (ArgumentNullException ex) { throw ex; } catch (ArgumentException ex) { throw ex; } finally { stream.Close(); } } //Bitmap转byte[] public static byte[] BitmapToBytes(Bitmap Bitmap) { MemoryStream ms = null; try { ms = new MemoryStream(); Bitmap.Save(ms, Bitmap.RawFormat); byte[] byteImage = new Byte[ms.Length]; byteImage = ms.ToArray(); return byteImage; } catch (ArgumentNullException ex) { throw ex; } finally { ms.Close(); } }
参考文章
，