We did some pattern dithering a year back on this site:

http://www.firstinflight.com.au

The nice thing about it is most of the backgrounds are 20kb jpgs which the dithering nicely hides.

Great stuff,

I’ve done a similar experiment back in February and posted something in March.
When I say pretty similar, I’m not kidding

http://tomaterial.blogspot.com/2008/03/dithering-in-actionscript-30.html

Posterization through paletteMap is implemented for the NO_DITHER mode…but…and here’s where I stumbled upon trying to “filterize+blendmode” the whole thing…these error diffusion kernels iteratively add to the image per pixel…the kernel runs from top left to bottom right and adds to pixels in between, finding the best color for them after they have been error-diffused….so far I haven’t come up with a blendmode + filter solution yet.

Just as an idea – how about adding the option to provide a custom color palette?

I haven’t tried it, but it might speed up your code event a little bit more if you use paletteMap first to do the quantization – here’s a posterization code from Peacock:

var levels:Number = __parameters.getValue(“levels”);
var r:Array = [];
var g:Array = [];
var b:Array = [];
var a:Array = [];

var vStepF:Number = 255 / levels;
var vStep:int = 0.5 + vStepF;
var v:int = 0;
for (var i:int = 0;i255) v=255;
a[i] = v << 24;
r[i] = v << 16;
g[i] = v << 8;
b[i] = v;
}

output.paletteMap(output,output.rect, origin,r,g,b,__parameters.getValue(“posterizeAlpha”) ? a : null);