screen printing > Separations
Ellipse Vrs Dot shape benefit "example attached"
Dottonedan:
When choosing a halftone shape when outputting films, you might ask yourself "Why would we use ellipse dot shape over a round dot?"
Using one or the other does not impact high end simulated process as much as it does lower halftone count that result in larger dots. It makes a difference in the visual appearance if your using lower halftone counts and printing a limited number of colors that lay on a contrasting color.
Using black ink on a white garment is a good example of that. The larger the dot, the more obvious the issues become. See the examples below to help explain.
You can see here that you only get about 8-9 dots of transition using (ROUND).
Here you can see that you get about 19-20 dots of transition using (ELLIPSE).
Command-Z:
I always thought ellipse was used in order to prevent moire.
DraginInk:
--- Quote from: Command-Z on April 05, 2011, 11:48:40 AM ---
I always thought ellipse was used in order to prevent moire.
--- End quote ---
Ditto.
EDIT: I guess I should add that for the last 8 or ten years the only time I break out the elliptic dots is for 4 color process which I rarely ever do any more. I started using round dots and the same angles somewhere in the automated separation program (actions) days .... I think it was Color Crunch that got me started on the roundy kick. I tried 'em ALL at some point.......
Strange... Just last week I was outputing some film and clicked on ellipse... just for old times sake.... you know what? IT WORKED! ;)
Printhouse:
I have done very little with half toning but realize that it is now time to start pushing some of my printing. I love to learn things like this.
Dottonedan:
Ellipse dots shapes are an added benefit to improving a 4 color process print (simply because of the smoother transitions) when using halftones. Not much mare to it than that.
It has very little to do with improving moire. If you are going to have moire issues, it's because of other issues the effect moire more directly and in larger, more impactful ways. Your are about 2-3% less likely to have moire issues... if you used elliptical dot shapes. Thats a guess at that specific number, but it's to illustrate how little the dot shape actually plays a role in improving moire.
The original maker of Color Crunch (Charles facini) and I had some pretty good conversations on this topic about 12 years ago and we were in agreement. 4 color process is done well with the same screen angle for all mesh. People love the "rosette" theory that you need a good rosette to create better color blends. Not true. Someone "recently" also showed me where a guru who wrote a book on the subject included that rosette pattern are needed to created better blending in CMYK. That guy made a mistake. :) Process inks are (translucent) inks and "require" the merging of dots to create other colors. Rosette patterns are formed due to an exact measurement of cross alignment thus forming this "rosette" shape. This "pattern" does not improve blending any more than a single screen angle does. If fact, it probably interferes with blending in a very small way more than it does benefit.
Tossing in the added variables of aligning "different' screen angles hoping that you don't get any moire is just compounding your potential problems. WHY?
Streamlines that process and use all of the same angles.
He's another thing to consider, Will all of the jobs that I do and the places I have worked outputting films/color separating for company's, it's been working for them all this time...without one complaint about my using all of the same screen angles. Some of these designs the company's have actually ran hundreds of thousands of shirts from. Very few were in that large of a number, but you get my point.
Another thing that gets me is that people will not blink an eye if I say sure, use a single screen angle of 22.5 degrees on all 10 screens of a (simulated process job). The moment I say to use that same screen angles with 4 color process. THEY SHREEK as if I had just cussed out Jesus himself. WHA?
LOL. This business is funny stuff.
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