How to sep out Simulated-Process Color in Photoshop?

[Raw Paw]

Hello mighty warriors of the print realm,

I am very familiar with separating prints using Index / dither, as well as CMYK.  However, I have never learned how to do Simulated Process, which I understand to be a multi colored halftone image, created with spot colors, with no overlapping dots (as opposed to CMYK).  I know this has something to do with channels... which I am pretty unfamiliar with.  For CMYK separations, for instance, I switch the image mode to CMYK, which automatically separates what become the different Cyan, Magenta, Yellow and Black screens for me.  Once I have the channels separated, I apply the halftone pattern using "Image - Mode - Bitmap," and manually enter in the angles of each respective layer.  For Index color / dither, I switch from RGB mode to Indexed Color, and select my ideal colors using the "pallete" - "Custom" at 150 DPI, and the image is separated into 150 dpi pixels in a finite amount of colors.

Not sure where to begin with Simulated Process.. any help or hints would be very appreciated.  I've attached some links for what I'm looking to achieve, the shirt pictured was printed by Holy Mountain in North Carolina using HSA inks.  Also, could someone explain the advantages of Simulated Process?  Does it work better for underbasing than an Index separation or CMYK?  I was reading wet on wet is easier to achieve on a white underbase using Simulated Process, whereas with a Dither all of the colors would start to muddy together..  And CMYK on a white underbase has been a headache to ever get to work (it requires me flashing every color and wiping the bottom of the screen with every print, to eliminate dot gain... defeats the purpose of wet on wet CMYK printing).  I also love how the pictured print will never fade in color and avoids the issues of discharge, in terms of yielding a more vibrant print and avoiding fibrillation of the shirt fibers over time.  Any help is very appreciated

[ebscreen]

Index has it's place but it's probably 1 for every 200 sim-process prints we do.
Generally speaking index will require more printed colors for an accurate reproduction.
Index seps are typically easier to create however, save for the underbase. Index underbase can be a bear to create.

Sim-process is how the shirt world rolls. Dots and even solids can overlap entirely. Selections from main composite image are made
(typically using "select by color range") and design is broken down into dominant colors with secondary and tertiary (and quaternary!)
colors made up from blends of them. Also, primary and secondary colors can be made drastically different depending on whether it is over
a base or not. That's one reason I strongly prefer sim-process with a base (any base) as opposed to straight discharge.

As for where to start:

Frog says we learn by teaching but I say we learn by doing!

Get you an image of medium complexity and start playing with color selections. That's really all
there is to it. Set your color selection channels to "Spot Color" and opacity of 5-65% depending on the ink/color.
IE your yellows will be at the lower range, and your whites will be at the upper.

Beginner underbases can be made by duplicating the image, converting to greyscale, making
selection of white, and saving to new channel in original image. As you progress you will learn where you need
more or less base depending on top color.

Get real good at it, then learn you'll never be as fast or as good as the guys that do this for a living, and start sending
it out.

hope that helps.

[Dottonedan]

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.

[Raw Paw]

Get you an image of medium complexity and start playing with color selections. That's really all
there is to it. Set your color selection channels to "Spot Color" and opacity of 5-65% depending on the ink/color.
IE your yellows will be at the lower range, and your whites will be at the upper.

Beginner underbases can be made by duplicating the image, converting to greyscale, making
selection of white, and saving to new channel in original image. As you progress you will learn where you need
more or less base depending on top color.

Thank you very much for the detailed and thoughtful response.  I played around with an image last night and learned some things...  As someone who has used photoshop for around 13 years but has very little understanding of Channels, this is a whole new ballgame.  I got some ok results, need to keep researching and practicing.

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.

I think I am understanding you right, and I read someone else explaining this yesterday in my research, but this doesn't make sense based on what I have learned in my print experience...  You print a dither / index print, on top of a halftone underbase???  I could see this working really well, it had just never occurred to me as a possible option..  Very cool..  Thank you for sharing!  As for 150ppi, I should probably re-test my dither resolution, but with our setup, I have found at 150 dpi dither translates perfectly to a 230 screen, and also works well in that it is half of 300 dpi...  the standard resolution we request from clients is 300 dpi, so if I need to dither one aspect of a separation, but leave the other smooth and undithered, I can dither the selected portion in a new file, decrease the size in half from 300 to 150, then rescale the dither back up to 300 dpi using "image size - nearest neighbor."  Each dither square goes from 1x1 pixel to 2x2 pixels, and duplicates back into the original file seamlessly.  Beyond this, every dot consistently and reliably exposes to a 230 screen.  I found a dither dot smaller than that didn't lost a lot of clarity on our separation printer and we couldn't expect for every dot to expose to the screen.  We have a load of 300 mesh screens but I hardly ever use them, might have to try again

[kidink]

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.

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?

[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]

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.

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]

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.

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!

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]

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.

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?

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]

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.

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.

[Dottonedan]

Glad to help...and especially, thank you for the feedback.  We often talk about what we do, but we don't always see too much feedback from others giving it a shot.  Thanks again!