making dot patterns in photos

[Visualaid]

good morning everyone,
customer gave me a 4 color job that needs to be 2 colors. I've got all that done, but when it came to making each picture duotone and sending it through the rip, the 2 colors were laying directly ontop of each other and they have same dot pattern so I am told one of the colors won't show up?
So I figured out a place in photoshop to make duotones and change the dot pattern with "curves", yet I don't know what I'm doing with the curve chart, I just mess with it until I can see both colors in a duotone picture in ROAM.
Can anyone tell me an easier way to change a dot pattern?
I thought Indesign or the RIP would have magically done it for me.
We put this job on a 4 color press which in my opinion should have been a 4 color job instead a 2 color job. I've never had to change dot patterns before, so why do I have to with duotones....
Please help

 

[Bret Hesler]

You need to change the angles of the colors in the RIP so that one is on 45 and the other is on 15 or 75. If you do not know how to do that, change the duotones to Black and Cyan or Black and Magenta.

Bret

 

[Visualaid]

angles in rip

angles in rip

i was digging around in the rip with a file after reading your reply, i do not see any menu to change angles of colors when double-clicking a file in the output controller. it gives page layout option and configure device option.

i can't believe a simple duotone file is this tough.

 

[DavidMa]

what two colors are you using for your duotone?

 

[michaelejahn]

Harlequin RIP ? Changing screen angles is easy

Harlequin RIP ? Changing screen angles is easy

i was digging around in the rip with a file after reading your reply, i do not see any menu to change angles of colors when double-clicking a file in the output controller. it gives page layout option and configure device option.

i can't believe a simple duotone file is this tough.

It is not that tough. People have been doing this since the 1990 when we printed directly from applications like Quark to a Linotronic.

You mentioned ROAM - Can I will assume you are using a Global Graphics RIP ? I will be happy to help you mouse through the dialog boxes to show you where you can change your screen angles.

if you email me off forum at michaelejahn ( at ) composeusa ( dot ) com we can set up a time - today is great (Today is Friday, July 15th, 2010 it is 7:00am pst here in California)

You may not be familiar with changing screen angles and probably have not had to many situations where you had spot colors (or better said, spot tints) where you needed to concern yourself with modifying the screen angle of a color. No Problem - it is pretty simple.

Even if you had a different RIP - there are several ways to do this. You can even do this from within the Print Dialog box within many adobe applications such as Adobe Illustrator...

To change the screen frequency, screen angle, and shape of halftone dots for a plate, double-click the ink name. Alternatively, click the existing setting in the Document Ink Options list, and make the desired changes. Note however, that the default angles and frequencies are determined by the selected PPD file, and using this approach might mean you need to set up your rip to let the PostScript file override the RIP settings.