Need to Register?

darwinchristian · 6 Days Ago

Well, i'm happy to say that last night i printed my first process color image, with decent results, i think, for my first time...

this was printed on a test pellon though. when i tried printing onto a 100% cotton white tee, the results were not as satisfactory... leaving what i believe to be "snowflaking" due to the fibers of the cotton and the need for more ink.

i have looked over Imageit's thread: Calibrated double stoke to eliminate snowflakes
for a while, and have yet to figure out how exactly to tailor my transfer function settings to my own needs. but i guess there, as for anyone, it will take some figuring.

I have printed 99 shades of black at 55 lpi to see where the highend and lowends drop out:

the black remains fairly solid through 90%, when shading is first visible, and on the other end 10% black seems to mark the end of any tangible shading.

with this in mind, i was wondering if any of you fellos out there who have walked the hard route had any info or advice to offer me in my new travels. i don't think this would help for the transfer function, as that seems like it would need much testing on my particular setup to properly adjust.

but is there a way to keep this in mind when i do my separations... for instance tweaking my colors to use less of the shades between 0-10, and 90-100%?

i realize my line of questioning is vague. i apologize. i guess i'm just looking for any tips before i spend the next month vigorously testing everything.

derek

ImageIt · 5 Days Ago

Quote:

Originally Posted by darwinchristian


	i realize my line of questioning is vague. i apologize. i guess i'm just looking for any tips before i spend the next month vigorously testing everything.

Your problem is that the smallest dots are burning away. The "easy" answer it to drop the LPI of the halftone. Drop own to a 35 LPI and all of the dots will be big enough not to get lost.

It is possible to modify the artwork not to need calibrating with a transfer function, by adjusting the output levels in the levels dialog box.

There is a downside to using the levels command, rather than a transfer function. By using a levels command, something you want to be printed BLACK would be output using a 90% screen. By using the transfer function, BLACK would be printed at 100%, which would cause an intentional over saturation of ink. While a transfer can give 110%, at 90% it would yield 90%.

The issue with using levels is that it will take as much testing to determine the correct value as you would using a transfer function.

If you have photoshop, it should only take a day. Your already very close.

The only thing which might take you a month is to find a good tutorial on how to use a transfer function in a program other than photoshop. I just attempted to find a tutorial on the subject and couldn't come up with anything.

fred

darwinchristian · 5 Days Ago

Quote:

Originally Posted by ImageIt


	Your problem is that the smallest dots are burning away.

makes good enough sense. i used ulano's QTX emulsion for the screens, knowing full well the resolution capabilities are limited on an ultra-fast emulsion. I mean to get a good emulsion for my exposure setup and will probably consult someone over to Ulano today or tomorrow. right now i am only holding a line weight of 0.3, positive and negative.

Quote:


	There is a downside to using the levels command, rather than a transfer function.

okay. i will focus on using the transfer function as opposed to the levels adjust. (something that is still somewhat of a mystery to me...)

i use both corel and photoshop. for the image above i output from corel with 55 lpi across the board and Jeff Proctor's CMYK angles 55, 22, 5, and 80, respectively. i think i'd like to try adobe's default screens for the next go, based on the info you had posted earlier in this thread about mathematical inconsistencies between the software and the RIP.

Also Fred-
just wondering if you've expirimented with other underbases for your process work besides a 110 "bulletproof" white... I saw someone post about a halftone underbase and thought about how much sweeter that could be...

thanks for the help and encouragement.

derek

ImageIt · 5 Days Ago

Calibrating a press is like tuning a musical instrument. Calling the manufacturer of the strings you are using, will not tune the instrument. At some point you just need to play a note, and turn the peg, play a note, turn peg and keep repeating the process until the setting produces the desired note. Postscript contains a transfer function for the same reason a guitar has tuning pegs.

For screen angle, i would suggest you measure the output angles and verify that you are getting out what you are expecting. The best way i know to do this is to scan the film on a flatbed scanner and measure angle and frequency within photoshop.

I'm still working on the white underbase. We've moved to a 156 mesh, from the 110. While not bulletproof, it is still bullet resistant. We're about to start testing things like soft hand additive.

In my brand testing, i saw that the brands have different bleed though characteristics. The shirts with the least bleed also had the softest hand. Hanes was the best, fruit of the loom was good and others were worse.

fred