[red514]

Hi All,
I've been testing some techniques using index and halftones and i've run into an issue.
I'm attempting to take an index print and out put with dots rather then squares (i need a lighter print and in theory this would be ideal).
I did a couple jobs on dark grounds that came out great. I used a 180ppi index separation and reduced the transparency to about 40% (this would generate 40% halftones) and output using 55lpi. what i didn't realize was that it wasn't converting each pixel to a halftone dot because my halftones at 40% were larger dots then my index pixels.

I just want to take an index pixel and have it print as a dot rather then a square. Is there an easy way to achieve this that i've over looked? i'm going to try more tests, i'm thinking there's probably an equation that would solve this.
if my image is 180ppi and i'm using 55lpi there's probably a percentage of transparency that would generate the halftone dots exactly the same placement as the pixel.

 

[ProSeparatorNJ]

That's an interesting problem. The problem is not the size of the square dot, but rather the opacity of it. Basically, a halftone is anything which isn't 100% solid color. So, as soon as you try something such as reducing the transparency, you're making halftones out of everything, including color that might have been solid black. I don't know what kind of result you will get, but If I had to do something like that and didn't have the original art, I would first try to get rid of the square dot. I might try blurring the art to remove the square dots. Then sharpening it again to start from scratch with a standard simulated process separation. If I had the original art I would simply re-separate it as a simulated process job.

 

[dot-tone]

You probably could get a (40% dot) to equal the size location of a square, but wow, you'd have to go up in line count very high. I'm not sure of the math. I never quite understood tha tpart or never took the tiem to think about it that hard. Some knnow that right off the bat. In fact, you know who might, is that guy on here that sells film and RIPs. I think he's from England or some place close to that. YOu might know who I'm talking about if you've been on here long enough. He's over at Theshirtboard also, but doesn't get on forums every day.

 

[red514]

That's an interesting problem. The problem is not the size of the square dot, but rather the opacity of it. Basically, a halftone is anything which isn't 100% solid color. So, as soon as you try something such as reducing the transparency, you're making halftones out of everything, including color that might have been solid black. I don't know what kind of result you will get, but If I had to do something like that and didn't have the original art, I would first try to get rid of the square dot. I might try blurring the art to remove the square dots. Then sharpening it again to start from scratch with a standard simulated process separation. If I had the original art I would simply re-separate it as a simulated process job.

The original index separation came out great but they want a more transparent look to the print (now i'm thinking of just asking the printshop to add some clear base or softhand to reduce the opacity).
I was going to re do the separation as simulated process but we've run out of time. Another option was 4c process but due to the high chance of color shifting (there's a nice Red in the design) during the run they won't risk it (print shop has never done 4c process before)

changing the transparency can work well depending on what you are trying to achieve. My first attempt i used 80% opacity, this worked but it wasn't generating any dots, it was actually generating the inverse (a negative space dot.. think that term makes sense). at 40% opacity it generated a dot (anything 50% or higher becomes checkered and then negative dot)
i'll post a pic of a job that came out nice, it's on a dark ground so it worked. on a light ground tho, all my shadows lost allot of detail and it's noticeable.

 

[red514]

You probably could get a (40% dot) to equal the size location of a square, but wow, you'd have to go up in line count very high. I'm not sure of the math. I never quite understood tha tpart or never took the tiem to think about it that hard. Some knnow that right off the bat. In fact, you know who might, is that guy on here that sells film and RIPs. I think he's from England or some place close to that. YOu might know who I'm talking about if you've been on here long enough. He's over at Theshirtboard also, but doesn't get on forums every day.

ya that's what i was thinking, i'll do more tests when i have time. i'll try seeing what using the same number of lpi as ppi (so a 180ppi image i'll try 180lpi) as well as different opacity's. i have a feeling this still won't work the way i'm hoping, i just want each pixel as a dot.

 

[red514]

This is a halftoned index separation. 55lpi @ 40%opacity

Trying to upload a pic from my phone but getting an error.