Author Topic: Halftone file for DIY films/screen testing and some pointers on calibration  (Read 51196 times)

Offline blue moon

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attached is the halftone test file for the screens and films.
This is what we use to calibrate the film output and see what we can hold on the screen.

Anybody interested in getting their RIP output calibrated can send the films to me for readings. I check it out and email the values to be entered in the RIP to produce calibrated output. My time is limited, so I can commit to one or maybe two of these per week. Films will go in the queue and will be checked on first come, first served bases.

If using it to check the screens, see what is the smallest percentage that opens. It is OK to spend a little bit more time washing those out, as we work harder in those areas too. What matters is that you can repeat the results.

For anybody sending the films to us, I very strongly suggest printing two copies and saving one as a reference. It is also a good idea to actually fill out the information on the top (instead of leaving our info) so you know the settings used. I've found that over the years we switch this and that and I have reference films that I don't know what's on them. Gradient and opacity should look the same. If there is any variation, there is a problem with your software.

45lpi is a good place to start as it is in my opinion a minimum needed to produce good prints (7-85% should be good). At 45lpi those numbers should be achieved pretty easily. Step up is 55lpi in 5-90% range and to get really good anything at 55 or smaller in 3%-95%. 230 mesh for 45lpi and 305 for 55lpi. These are guidelines, not rules, so feel free to experiment.

Let me know if there are any issues with the file. I have it as an ai and eps if needed.

pierre
« Last Edit: May 04, 2013, 09:31:34 AM by blue moon »
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!


Offline blue moon

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Re: Halftone test file for the films and screen
« Reply #1 on: May 03, 2013, 07:30:08 PM »
few things to look for is any banding in the gradient strip, jaggy transition from halftone to solid on top of the strip and closed in dots at 90% or more. Your film output device should be producing very small holes at 99% whereas 100% should be solid.

traditionally, ghostrip produced 60%+ at 50% and AR is usually above 70%. This is based on tests with our equipment and other ppl sending films for reading.

pierre
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!

Offline blue moon

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Re: Halftone test file for the films and screen
« Reply #2 on: May 03, 2013, 07:42:49 PM »
and here is ball park what a 50% image should look like. The rows should be slightly closer together, but the distance (end to end) between the dots is about right.

If your dots are joining before 70%, the dot size is too big.

pierre
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!

Offline Screened Gear

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Pierre,

I applaud your willingness to help here. You my friend get 10 respect points.
« Last Edit: May 04, 2013, 12:43:17 AM by Jon »

Offline Screened Gear

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Well I haven't looked at my printers dots in a while. I think I need to calibrate it a little (not as smooth as they should be)

Here is my 50 and 45% dots. I am off but not as much as i figured. Still need to get my rip set perfect for my new printer. These photos are at 800 percent magnification. I know a little over kill. They are also blurry.

« Last Edit: May 03, 2013, 08:19:52 PM by Jon »

Offline blue moon

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that looks like a round dot to me . . . do you have it set up as elliptical?

pierre
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!

Offline Screened Gear

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They look square to me. It was set to elliptical. It was done with ghost script.

Offline Dottonedan

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Jon,  is your printer using toner or digital ink?  Looks like toner. Pretty undefined edges.
Artist & Sim Process separator, Co owner of The Shirt Board, Past M&R Digital tech installer for I-Image machines. Over 28 yrs in the apparel industry. Apparel sales, http://www.designsbydottone.com  e-mail art@designsbydottone.com 615-821-7850

Offline GaryG

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That's on film correct?
What printer?

Looks like --white paper-- and texture of it making edges rough
or inkjet ink splatter... Which is pretty normal at that magnification.

Offline blue moon

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the round dots convert to squares around 50%. It is not as prominent with the elliptical dots. Here's a picture of our 50% dots produced at high speed settings (they clean up when printed in one direction only).

pierre
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!

Offline GaryG

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Definitely 2 different output devices. It would be nice to know
which ones?

We have a Epson 1900 with 8 cartridges. Specs mentioned smaller
droplet than say a 1400.

Seems ours spatters in-between Jon's and yours Pierre.

Offline blue moon

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the image is from the 4800. Dots on the 1400 are much cleaner than the 4800, but it was just too slow and cumbersome to use. going to printing in one direction cleans the dots up quite a bit. I'll see if I can print a test page and take some pix . .

pierre
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!

Offline blue moon

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here's the single direction print, it is a little bit cleaner. output is not calibrated for single pass, so the dot size is a little bit different. One big difference is that there are no stray dots and what is there is just a little less bumpy.

pierre
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!

Offline GaryG

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I know the secret to your success Pierre-
You clean up all your halftone edges with an X-acto knife. lol

Offline blue moon

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and the same dots at 2880x2880 . . .
Yes, we've won our share of awards, and yes, I've tested stuff and read the scientific papers, but ultimately take everything I say with more than just a grain of salt! So if you are looking for trouble, just do as I say or even better, do something I said years ago!