How to Display 16-bit grayscale

Im currently displaying a grayscale image (black and white) using 8
bits. I am able to display a nice gradient from black to white in 256
steps.

video_buffer = (_uchar8)ddsd.lpSurface;
video_buffer[ row * bytes_per_line + col] = RGB( col , col, col); //Use
the same value for red, green blue to get b&w

Now, I would like to display another image (black & white grayscale)
using 16 bits per pixel. How can I display a grayscale to go from pure
black to pure white with 16 bits of resolution (2^16 steps)?

I tried this, but it didnt work:
video_buffer = (_ushort16)ddsd.lpSurface;
video_buffer[ row * bytes_per_line + col] = _RGB16BIT( col , col, col);

Aside from the fact that the eye cannot make the difference between
more than lets say
256-1024 shades of gray, there is no display hardware that can show
more than 10 bit of color as far as I know. I've seen some time ago a
commercial of a TV set that claimed 8 billion colors, but I believe is
was just "smarketing".

If you really need the extra detail, then you'll have to make use of
normal colors instead of extra gray level. That may work if you want to
display more detail of a x-ray, for example.

How to Display 16-bit grayscale - Java-Games