用OpenFileDialog打开图像文件，文件名为filename
StreamReader sr = new StreamReader(filename);
Stream sm = sr.BaseStream;
imgZheng = Image.FromStream(sm);sm.Close();
sr.Close();//将读取到的Image重新写入流，转化为byte[]以便进行进一步的处理
MemoryStream mmstream = new MemoryStream();
imgZheng.Save(mmstream, ImageFormat.Png);//执行到此处时会出现“GDI+中发生一般性错误”这个错误。byte[] imgByte = null;
imgByte =  mstream.ToArray();

byte[] ImgByte = null;MemoryStream mStream = new MemoryStream();Bitmap bmp = new Bitmap(filename);bmp.Save(mStream, ImageFormat.Png);ImgByte = mStream.ToArray();bmp.Dispose();mStream.Close();MemoryStream mstream = new MemoryStream(ImgByte);imgZheng = Image.FromStream(mstream);mstream.Close();

//此时再执行Save方法，将不会报错  　　　　　　　　MemoryStream mstream = new MemoryStream();                imgZheng.Save(mstream, ImageFormat.Png);

 　　　　　　　　　　　StreamReader sr = new StreamReader(filename);Stream sm = sr.BaseStream;Image img = Image.FromStream(sm);img = Image.FromStream(sm);
　　　　　　　　　　　//将图像序列化给指定的流，再将流序列化为二进制数组。BinaryFormatter binaryFormatter = new BinaryFormatter();MemoryStream mstream = new MemoryStream();binaryFormatter.Serialize(mstream, img);byte[] ImgByte = mstream.ToArray();mstream.Close();sm.Close();sr.Close();//将二进制数组放到流中，再反序列为图像MemoryStream memostream = new MemoryStream(ImgByte);imgZheng = (Image)binaryFormatter.Deserialize(memostream);memostream.Close();

//此时再执行Save方法，将不会报错  　　　　　　　　MemoryStream mstream = new MemoryStream();                imgZheng.Save(mstream, ImageFormat.Png);

StreamReader sr = new StreamReader(filename);Stream sm = sr.BaseStream;Image img = Image.FromStream(sm);img = Image.FromStream(sm);MemoryStream mstream = new MemoryStream();img.Save(mstream, ImageFormat.Png);byte[] ImgByte = mstream.ToArray();mstream.Close();sm.Close();sr.Close();MemoryStream mmstream = new MemoryStream(ImgByte);imgZheng = Image.FromStream(mmstream);mmstream.Close();//此时再执行Save方法，将不会报错  　　　　　　　　MemoryStream mstream = new MemoryStream();                imgZheng.Save(mstream, ImageFormat.Png);