draw a 16bpp unindexed image on PC linux

["sanju reddy gopidi" <sanjugopidi rediffmail com>]

Hi all
Iam facing bit problem using GDK APIs.
Current APIs for 8bpp display on X86 desktop Linux are:
GdkRgbCmap *colormap;
colormap = gdk_rgb_cmap_new (shared_stuff->shared_colors, 256);
gdk_draw_indexed_image (widget->window, widget->style->fg_gc[GTK_STATE_NORMAL],
                            image_start_x_coord, image_start_y_coord, image_width, image_height,
                            GDK_RGB_DITHER_MAX, rgbbuf, image_width, colormap);

And this is working excellently for 8bpp on Linux desktop(is PC simulator)

Now i want to replace these APIs with the APIs which are meant for 16bpp.
But as iam novice to this GDKGTK stuff Please help me in this 
APIs

Which APIs i should use for drawing un indexed images?

Thanks in advance!!
Sanjeev