title: Image conversion : RGBA to RGB
body: <p>assuming i had RGBA (32 bits) output from frame-grabber, with alpha channel unused (values retained while filled by frame-grabbers), is there any effective conversion method to RGB (24 bits) ?</p>
  
  <p>I am dealing with 5 MegaPixels streaming images so speed does matter too.
  keep in mind that data in alpha channel can be discarded.</p>