Convert Index Colors to Layers or Channels

[Ciminelli]

Hello Photoshop community!

This might be a niche idea for photoshop as it caters to my specific profession but I feel that what I am looking for wouldn't be all that hard for photoshop to accommodate.

I own and operate a screen printing facility that primarily prints custom apparel for touring musicians and entertainers. The screen printing process requires that we separate art in to a chosen palette of spot colors--it's very rare that we print using a CMYK process.

We are commonly provided art files that are complicated to work with and generally not "print ready". Taking rasterized files and breaking them in to spot colors is a HUGE headache and sometimes downright impossible to do manually. I've tried many scripts and tutorials and I do consider myself pretty proficient in photoshop but nothing I do manually can separate an image quite right. As a result, we're forced to spend hundreds of dollars a year on separation software and even that doesn't always work.

What I would love is the functionality of the Image > Mode > Indexed Color wherein my final result is separated in to individual channels that I can see in the channels window. If I could extract channels or even layers from the 'Indexed Color' process, that would allow me to separate any art file in to the spot colors that I need to run a screen print. It would also take little to no time/effort which can't be said for current separation processes.

I'm extremely envious of CMYK printers because Photoshop provides these channels to them by default. For all of us spot color printers, this functionality would be INCREDIBLE. I'm no programmer but I feel like Photoshop has the capability of doing this already via the Indexed Color process but as it functions right now, I don't get custom channels as a result--just a flattened art file that doesn't really help me in any way.

That's my idea--if anybody has a solution for this already, I would LOVE to hear.

Thanks!

[Stephen Marsh]

@Ciminelli 

I have upvoted your feature request.

Compared to offset/litho or digital, screenprint can use many more colours – but certainly less than the indexed color 256 max palette.

Are you currently successfully using Indexed Color mode? If so, how do you do things manually? How do you reduce/simplify complex artwork down to a smaller restrictive palette?

Although tedious, you can dupe the current file X amount of times for each indexed colour, then use Image > Mode > Color Table and make all colours white and make the target colour black, so that in effect you have a document as a solid black & white separation, then convert to Grayscale mode and repeat for the other docs, before merging channels back to a single doc and then making the separate channels spot channels.

This can be semi-automated to various degrees using actions or scripts.

[Stephen Marsh]

As a proof of concept, I tested an action to semi-automate the creation of 3 spot colour work via indexed colour mode. A separate action would be required for 2 colours, 4 colours, 5 colours etc. 

[rayek.elfin]

What I would love is the functionality of the Image > Mode > Indexed Color wherein my final result is separated in to individual channels that I can see in the channels window. If I could extract channels or even layers from the 'Indexed Color' process, that would allow me to separate any art file in to the spot colors that I need to run a screen print. It would also take little to no time/effort which can't be said for current separation processes.

By @Ciminelli

Separating colours into (named) layers can be done automatically in Krita. Krita is free and open source: download it from krita.org.

Import your indexed coloured version and choose Layer-->Split--> Split Layer.

It will even automatically name the layers according to the colours. And it is possible to use your own palette, if need be - handy for your spot colour scheme. Save the result to PSD and load the result back in Photoshop (if required) to convert those to spot colours.

It may potentially save you a lot of time and headaches when prepping for screen printing.

By the way, Photoshop's conversion to indexed mode leaves something to be desired. There are better tools to generate an indexed colour reduced version at higher quality and with far more contol over the end result. I prefer Color Quantizer myself.

https://www.softpedia.com/get/Multimedia/Graphic/Graphic-Others/Color-quantizer.shtml

Krita also has an interesting Palettise function that allows you to feed it a specific limited colour palette and an Indexed Colours function for additional control.