bitmap - JPEG decompression from MemoryStream c# -

in program, compress bmp jpeg 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 function receiving jpeg in memorystream, transform bitmap doing

bitmap b = new bitmap(stream); 

when display image, there lot of lines :

what doing wrong, people?

edit 1 here small visual studio solution showing problem: http://www.fast-files.com/getfile.aspx?file=79311

it beginning of screen sharing software. does: takes screenshots, compare them, compress difference , send part of program decompress , recompose image received. opens window displaying "sent" on left , recomposed image on right.

three things come mind:

1. try setting better quality 30 , see if helps;
2. check ram (and possibly video ram, though doubt gdi+ might use vga compression) hardware problems;
3. i've had similar weird problem loaded jpeg file, modified bit, , saved again. produced exception. solution make new bitmap based on old 1 , save copy. try that.