extraction of color channels out of bitmaps

hi all!

i'm trying to extract one color channel (i.e. the red channel) out of a RGB bitmap:

for(x=0;x<CAM_W;x++)
{
for(y=0;y<CAM_H;y++)
{
BitmapUtil.SetPos(TPoint(x,y));
pixel = BitmapUtil.GetPixel();

color = TRgb(pixel);

value = color.Red();

color.SetRed(value);
color.SetGreen(value);
color.SetBlue(value);

BitmapUtil.SetPixel(color.Value());
}
}

but it seems that either the color getter or the set functions of TRgb don't work correctly.

any hints?

thx in advance
mugi