anamya wrote:We do it because woot requires us to. Believe me, if I didn't have to, I wouldn't. You are only allowed six colors total on an image. (Plus negative space of shirt color.)
I don't understand why illustrator users aren't required to though. They are supposed to leave the gradients in. Doesn't make any sense to me.
Are you sure Woot requires you to?
Illustrator uses spot color, which is equivalent to the ink color you want to use. You can specify a percentage of this spot color, 0% being no color, and 100% being solid color. A gradient is a blend from 0%-100%. This is output to a film through software called a RIP. Its sole purpose is to generate halftones from these percentages. It is quite costly, usually around $500. It can also generate halftones from a Photoshop file, if it is saved as a multi-channel DCS file. Each layer, saved as a channel, is assigned a different spot color. Same principle when sent to the RIP.
The thing is, if you don't know what you're doing, it's easy to end up with something called moire. Say you use an arbitrary LPI of 52. If they then print on a mesh with 156 threads per inch, you get interference (52 * 3 = 156, which is bad).
Also, I've seen people use unattractive angles such as 90 degrees for their halftones.
And thirdly, anything over 60 LPI is too fine for screen printing. And under 10% or over 90% isn't printable either. I could go on.
I don't understand why Woot wouldn't want control over how halftones are generated. The designer could specify whether they want dots or lines, but beyond that, the printer knows best.
End of two cents.