如何在C＃中将位图对象保存为jpeg文件

Question

我有一个返回位图对象的函数。如何在C＃中将这样的对象保存为jpg文件？

到目前为止，我有这段代码

b = MakeGrayscale(b);
b.Save("C:\\test.jpg");

我收到此错误消息

{“GDI +中发生了一般错误。”}

StackTrace

   at System.Drawing.Image.Save(String filename, ImageCodecInfo encoder, EncoderParameters encoderParams)
   at System.Drawing.Image.Save(String filename, ImageFormat format)
   at System.Drawing.Image.Save(String filename)
   at Convert.Program.Plot(Byte[]& fileBufferArray, Int32 fileSize, Int32 offset) in C:\Users\Administrator\Documents\Visual Studio 2010\Projects\Convert\Convert\Program.cs:line 151
   at Convert.Program.Main(String[] args) in C:\Users\Administrator\Documents\Visual Studio 2010\Projects\Convert\Convert\Program.cs:line 42
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

有人可以帮助我吗？