JPEG decompression from MemoryStream c#

Question

In my program, I compress a BMP into a JPEG like this:

private void ConvertBmpToStreamJPG30(Bitmap b, Stream s)
{
  s.Flush();
  EncoderParameters encoderParameters = new EncoderParameters(1);
  encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 30L);
  b.Save(s, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}

Then a function is receiving the JPEG in a MemoryStream, I transform it into a Bitmap by doing

Bitmap b = new Bitmap(stream);

When I display the image, there are a lot of lines like this :

Screenshot

What am I doing wrong, people?

Edit 1 Here a small visual studio solution showing the problem: http://www.fast-files.com/getfile.aspx?file=79311

It is the beginning of a screen sharing software. What it does: It takes screenshots, compare them, compress the difference and send it to another part of the program that decompress it and recompose an image with everything received. It opens a window displaying what is "sent" on the left and the recomposed image on the right.

looks like corrupt data stream - does the jpeg open correctly in other apps? — Sten Petrov, Sep 22 '14 at 13:54
Can you produce a short but complete program demonstrating the problem? If you save the stream to disk, can you open it with explorer etc? — Jon Skeet, Sep 22 '14 at 13:54
Why Flush() before Save()? Is the position of s at the beginning of the stream? — Thomas Weller, Sep 22 '14 at 13:55
Also, can we get the exact bitmap file which produces this artifact? — Vilx-, Sep 22 '14 at 13:55
Do you know that the original BMP file does not have these problems? — user3344003, Sep 22 '14 at 19:35
Yes, I tested it by displaying the original one and it worked just fine. — Poutchyouk, Sep 23 '14 at 08:13

score 0 · Answer 1 · edited May 23 '17 at 12:21

Three things come to mind:

Try setting a better quality than 30 and see if that helps;
Check your RAM (and possibly video RAM, though I doubt that GDI+ might use VGA for compression) for hardware problems;
I've had a similar weird problem where I loaded some JPEG file, modified it a bit, and then saved it again. That produced an exception. The solution was to make a new bitmap based on the old one and save the copy. Try that.

JPEG decompression from MemoryStream c#

1 Answers1