Drawing alpha masked images

[Mobeen]

I am making a simple demo in which i m trying to draw a 2d image to show the misses left. Now the image is an 8bit png with alpha channel stored to mask out the ship image but when i render the image the alpha mask is not applied, I am doing this
drawImage2d(img, point2d<s32>(570,10));

Wuold i have to mask alpha myself???
Thanks
Mobeen