attach image without saving

[mind_freak]

i want to attach image to my e-mail but without saving to phone,i can save image to buffer by writing the code given below:

     QByteArray ba;
     QBuffer buffer(&ba);
     buffer.open(QIODevice::WriteOnly);
     bool error=imageWithOverlay.save(&buffer,"PNG");

Now how to retrive the image back from buffer and attach it to mail ??