Dithering for clocks, etc

That looks really neat! There are actually some options that might help you to do it without having to have separate images for each colour (or dither/non-dithered):

• When given a 1 or 2 bit unpaletted image, g.drawImage will use the background + foreground colors - so using a pre-dithered black and white image will then allow you to draw that out in whatever colors you want (or fg+bg the same to have no dither). Using 2 bit allows you to get black+white, plus another color used to signal transparency.
  
• It might be possible to use g.drawImages to layer up the number as well as your dither pattern