screen printing > 4 Color and Simulated Process Printing
How to sep out Simulated-Process Color in Photoshop?
Sbrem:
I have a print that Dan separated for Pierre that mixes both, and is a fabulous print; dither/index images don't do particularly smooth gradations in the fades to shirt color, where as halftones do. As others say, index under bases can be a pain. One trick I tried was to take the underbase image to a separate file, (similar to Dan's description above) make sure it's grayscale, quadruple the resolution, then choke it. At 150, you'd be upping to 600, make sure Resample is checked.) This way you can choke them by 1 pixel or 2. Convert it back to Bitmap (threshold) and print out separately. The squares are still in the same place, just a little smaller. If you try to bring it into your 150 index file, they won't match resolution wise... Maybe you could check out something like QuickSeps, which automates the process, though it still needs tweaking. You can study some of the samples to help you wrap your head around it.
Raw Paw:
--- Quote from: Sbrem on February 10, 2020, 02:06:53 PM ---I have a print that Dan separated for Pierre that mixes both, and is a fabulous print; dither/index images don't do particularly smooth gradations in the fades to shirt color, where as halftones do. As others say, index under bases can be a pain. One trick I tried was to take the underbase image to a separate file, (similar to Dan's description above) make sure it's grayscale, quadruple the resolution, then choke it. At 150, you'd be upping to 600, make sure Resample is checked.) This way you can choke them by 1 pixel or 2. Convert it back to Bitmap (threshold) and print out separately. The squares are still in the same place, just a little smaller. If you try to bring it into your 150 index file, they won't match resolution wise... Maybe you could check out something like QuickSeps, which automates the process, though it still needs tweaking. You can study some of the samples to help you wrap your head around it.
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Awesome, thanks for this tip! This choke method you are describing is for doing a dither underbase, as opposed to a halftone underbase, correct? That is a cool trick!
Sbrem:
--- Quote from: Raw Paw on February 10, 2020, 02:43:26 PM ---
--- Quote from: Sbrem on February 10, 2020, 02:06:53 PM ---I have a print that Dan separated for Pierre that mixes both, and is a fabulous print; dither/index images don't do particularly smooth gradations in the fades to shirt color, where as halftones do. As others say, index under bases can be a pain. One trick I tried was to take the underbase image to a separate file, (similar to Dan's description above) make sure it's grayscale, quadruple the resolution, then choke it. At 150, you'd be upping to 600, make sure Resample is checked.) This way you can choke them by 1 pixel or 2. Convert it back to Bitmap (threshold) and print out separately. The squares are still in the same place, just a little smaller. If you try to bring it into your 150 index file, they won't match resolution wise... Maybe you could check out something like QuickSeps, which automates the process, though it still needs tweaking. You can study some of the samples to help you wrap your head around it.
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Awesome, thanks for this tip! This choke method you are describing is for doing a dither underbase, as opposed to a halftone underbase, correct? That is a cool trick!
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Yes, it's for choking the dither under base. You might have to upses to higher than 600, but this gives you the basic idea.
Steve
Dottonedan:
--- Quote from: kidink on February 09, 2020, 10:24:11 AM ---
--- Quote from: Dottonedan on February 08, 2020, 12:48:59 PM ---Eb made some excellent statements and suggestions. I don't have much to add to that other than to use a traditional dot on the base of an index print. Idex is dot next to dot. Fully underbased with a white dot. Yuk.
I've attached a pic of a stochastic (same square dot but mixes like sim process) print I did separations for a guy in Canada. Index is dot next to dot. We used a traditional halftone base of 55lpi on 230 mesh. This allows the shadow colors to darken more (giving more life) or dimension to the print. With a solid dot over dot, you don't get any tonal transition and need to rely totally on the DPI of the print for your eyes to blend. With Sim process, you are using shirt color, and ink blending of wet on wet...to gain a far more full color transition physically in the print process than jsut relying on the file resolution. 150ppi by the way, is low in my opinion. I use 233, on 305 mesh and 266 on 340 mesh. These two mesh counts at that resolution and (with many colors), help create excellent prints. But at the cost of more colors, more setup time.
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Looks great, can I ask why the decision was made to do this as a stochastic dot over a hafltone underbase as opposed to angled hafltone for each colour?
I'm assuming it was separted in the normal way and then converted to halftones using a RIP?
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It was used to improve the over all amount of subtle detail in the art, hold texture and to permit smooth color transitions/blends without a lot of dottiness (if that's a word). LOL.
An addition benefit as a result of the need for high mesh, is the softer hand. With traditional dot, you might be more inclined to use lower mesh/heavier coverage.
Raw Paw:
--- Quote from: Dottonedan on February 11, 2020, 02:04:12 PM ---It was used to improve the over all amount of subtle detail in the art, hold texture and to permit smooth color transitions/blends without a lot of dottiness (if that's a word). LOL.
An addition benefit as a result of the need for high mesh, is the softer hand. With traditional dot, you might be more inclined to use lower mesh/heavier coverage.
--- End quote ---
Thanks for your help in this thread. I ran some tests last week following your advice and got tremendous results. The halftone underbase provides a ton of shadow contrast, and the dither colors on top blended precisely how you had mentioned.
My exact specs (handprinted):
Discharge white underbase printed with 45 frequency halftone pattern at 61 degrees on a 230 mesh (1 load, 2 hits)
-Flash-
3 color dither @ 150dpi, printed on 305 screens with plastisol, wet on wet (all 1 load, 1 hit)
I can probably go smaller with the dots, but honestly this produced amazing results. Using smaller dots presents its own variables with our film printer, being able to easily expose and washout the screen, ect. I'd rather just go with what works and still looks great. I also did tests with a different underbase - 50 frequency halftone pattern at 61 degrees, 230 mesh - it didn't turn out as nice. The larger size of the dots and greater separation between them (at 45 freqency) seems to give more depth and contrast, probably due to avoiding dot gain. I tested the two underbase screens with 80/20 discharge underbase, white discharge underbase, and plastisol white underbase, the discharge white gave incredible results. The plain 80/20 discharge underbase needs a highlight white, and the plastisol white underbase gave much more dot gain on the dither layers on top, and also needs a white highlight to look nice.
I may continue exploring simulated process, specifically in using halftones only for color separation, but I don't like the process of using "color range" and channels... I don't like the ambiguity of it, and how much gray area there is in the process. Index separation is awesome because I can fly through it in 10 minutes and get reliable consistent results every time. The sample I printed has so much more depth than the way I have been handling index separation, which is only using discharge inks without an underbase.. We run into problems with the ink drying (Texas summer can be cruel when it comes to wb discharge), color saturation, ect. The ability to use plastisol on these jobs, without having to worry about the ink drying, or wasting activated ink, mixing new ink every day and achieving brighter colors is truly a game changer.
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