[magick-users] Dither 24bit images to 16bit (aka truecolor to hicolor)

[jore at stachelig.de]

Hello all,
I use an old LCD screen with proprietary graphics card as a digital
picture frame. Unfortunately the graphics card only allows "hicolor" mode
(16 bit/pixel) at full resolution due to it's limited vram.
Thus some images, especially those with smooth gradients (like blue skies
etc.) show a quite noticeable banding. My idea is now to dither (error
diffusion or whatever) the 24bits/pixel images to 16bits/pixel for
displaying them; this shouldn't be too big a problem I guess.
Is it possible to do this with ImageMagick, or do I have to code this
myself? I would only do the conversion with IM btw, for displaying the
images I have a small self-written app that mixes images from certain
sources.

Thanks in advance,
   Joerg