QTR-Quadtone RIP

Hi david,

I've made digital positives for photopolymer intaglio prints with QTR with good success.

I'm not sure if you count on QTR to create the aquatint dithering. Anyhow, at least given your requirements, it will not. You will have to create the dithering pattern in eg photoshop. I use andromeda screen filter for this. The result should be a black and white image (no gray tones). The dots are formed in Photoshop, not QTR. Any consideration with respect to percentage coverage of the dithering pattern is to be handled in photoshop, again not in QTR.

Next you'll have to create a QTR curve. I suggest you read Tom More's manual. In your case, it's actually much simpler than a normal curve as you should only be concerned by the blacks, as the image does not contain any gray levels. Apperently, you already know you need magenta and yellow in a certain ratio. But be carefull not to overload, I would be concerned that a curve with 94% of the maximumlevel of one ink + 75% of the other would be way more then the medium can absorp. 

What are you printing on? I have printed on Agfa Copyjet. After some experiments it turned out that in my case just matte black gave the highest density. Any experiments with photoblack and magenta gave much less density. But I guess that's very dependent on the situation.

Joost
 


 

--- In QuadtoneRIP@yahoogroups.com, "David" <dkfreed@...> wrote:
>
> I have an off-beat request: I'm trying to create, on transparency film, an image made up of dots, where the darker tones have the dots spaced closer together and the lighter tones have the dots spaced farther apart. 
> 
> I'm using this to create a photopolymer etching plate; for those unfamiliar with this, its probably most similar to screen printing, 
> 
> Using QTR, I'd be printing these at 720 or 1440 ppi. 
> 
> Here's the kicker: I'd like EACH DOT to be the same color, using about 94% magenta and 75% yellow ink. (The range of tones in my image file range from about 80% to white, so there is no pure black and no place in the image where the dots would totally fill up the space.)  
> 
> Could someone tell me what density and ink limit settings I'd need for both the magenta and yellow inks. 
> 
> I'm a novice to QTR. I asked this question a few years ago, but I'm not getting the results I need based on past advice. 
> 
> kind regards, david 
> 
> Best, David.
>