JpegBitmapDecoder decode jpeg failed?

Question

I'm using the following code to Decode Jpge image

UnmanagedMemoryStream^ mStream = gcnew UnmanagedMemoryStream(_jpegDataBuff, _buffLength);
JpegBitmapDecoder^ decoder = gcnew JpegBitmapDecoder(mStream, BitmapCreateOptions::PreservePixelFormat, BitmapCacheOption::OnLoad);
BitmapSource^ bitmapSource = decoder->Frames[0];

I use the bitmapSource to display on control of WPF, but sometimes the the result as below

I have searched very much on internet, but I did not solve it yet!

Someone can help me?

Many Thanks,

T&T

Answer 1

From the looks of it I would say that either JPEG source is incomplete or invalid. The only exceptions JpegBitmapDecoder throws are ArgumentNullException (stream is null) and FileFormatException. The file format is most probably detected by analyzing file header. The JIF/JFIF file structure holds image description information in a relatively small header followed by a "raw" data.

I guess that decoder is built resilient to ignore invalid (rendered last before gray) and/or missing (rendered gray) blocks. I think the only way to detect is to either analyze final image (maybe checking that last 8x8px block doesn't have same color?) or source (maybe counting data blocks?).