QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Roy Harrington <roy@...> wrote:
>
> Hi David,
> 
> The only way to get specific ratios of two inks is to mix the inks by
> hand and load the
> mixture into one of the ink carts.  The printers only output up to 3
> different ink drop sizes
> so the printer itself can't do what you are asking for. 

This is true indeed if you actually need a dithering of the digital positive/negative the printer's resolution. However, if you can live with lower resolution it is feasible to mix on the "dither dot" level using standard inks. As said, I did so for a photo-polymer intaglio-process. I resized the original file to 2880dpi, applied the Andromeda screen filter (resolution ~300 lpi). The resulting (black) dots where then printed in several ink mixes. As you can overload a bit, you can get quite good mixing. With a 8x loupe I could not recognize individual dots.

So it depends quite a bit on the resolution you require. The photopolymer process I used could not handle finer resolutions anyhow, so the process worked fine for me. 

Joost