Skip to main content
ottoGraphic
ottoGraphic
Participating Frequently
November 3, 2023
Answered

Converting process colours to spot colours in Photoshop

  • November 3, 2023
  • 3 replies
  • 2025 views

Here is a question about converting process colours to spot colours in Photoshop. Is there a straightforward way to change CMYK to 2 or 3 chosen (spot) colours, let's say red, green and blue, which I would like to print with. I am a graphic artist and screen printer so I do all the printing myself. I know that the printed image won't be an accurate representation of the original photo, but I would like the best approximation possible. I've tried manually modifying the CMYKs in Multichannel, but I can't get a decent result. Does Photoshop have a way of doing this? 

    This topic has been closed for replies.
    Correct answer Stephen Marsh

    Well, much appreciated Stephen, that's given me some good bits of advice.

    Thanks for taking the time.


    @ottoGraphic – You're welcome!

    3 replies

    Jumpenjax
    Community Expert
    JumpenjaxCommunity Expert
    Community Expert
    November 3, 2023

    Image/ mode/ RGB. Unless I misunderstood what you are asking. That is the easiest way I know.

    Lee- Graphic Designer, Print Specialist, Photographer
    ottoGraphic
    ottoGraphicAuthor
    Participating Frequently
    November 4, 2023

    thanks for the suggestion, I have looked at the RGB option, but I can't find a way to turn them into printable colours. I am actually going to print manually with ink on paper.

    Stephen Marsh
    Community Expert
    Stephen MarshCommunity Expert
    Community Expert
    November 3, 2023

    Straightforward? Probably not. The easiest way would be using a multi-channel ICC profile.

     

    It really depends on the image content.

     

    Can you post a sample image?

    ottoGraphic
    ottoGraphicAuthor
    Participating Frequently
    November 3, 2023

     

    This is the photo I am experimenting with at the moment. RGB would be the obvious way, but how do I extract printable colours from that? I'll have a look at how to do the MC ICC profile.

    ottoGraphic
    ottoGraphicAuthor
    Participating Frequently
    November 4, 2023
    quote

    I am quite used to crafting my own channels, but I understand my only option in PS is to start from the CMYK channels?


    By @ottoGraphic

     

    Sometimes the C, M or Y channels are easier, but unless you start from a conversion to a specific profile, the RGB are often *similar* but not the same.

     

    R = C (cyan is a strong component of blue, so a good start for a spot blue channel)

    G = M (magenta and yellow are a strong component of red, so a good start for a spot red channel)

    B = Y

     

    Sometimes Lab mode is good, one can use the "a" channel (opposing magenta/green) or the "b" channel (opposing blue/yellow) with edits to change colour, biasing/targeting a required hue, then convert back to RGB and then make use of that channel for blending etc.

     

    Of course it isn't that simple, but it's a good start point before considering ink limiting, TVI and gray balance/neutrals.

     

    It really comes down to using Apply Image with different blend modes, opacity, inversion etc. Curves, channel mixer etc. Visual preview is hard, info panel to find what mix of channels is in play for each colour is critical.

     

    Edit: Attached is a conversion using one of those free MC profiles (use Photoshop to view of course).

     

     


    Interesting, some food for thought there. I've never used Lab mode, not sure how that works, but I'll look into it.

    I have now manually crafted the channels using a mixture of RGB and CMYK channels, masks and such like, then applied a dot screen. It's a lot of fiddling around, and I was hoping there was an easier way, but I have attached a screen shot to show the kind of result I'm after.

    kglad
    Community Expert
    kgladCommunity Expert
    Community Expert
    November 3, 2023

    in the future, to find the best place to post your message, use the list here, https://community.adobe.com/

    p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post (like this one has already been moved) if it helps you get responses.



    <"moved from using the community">
    ottoGraphic
    ottoGraphicAuthor
    Participating Frequently
    November 3, 2023

    Thanks for moving the post, I was unaware that I was using the wrong forum.

    Terms & ConditionsAccessibility statement
    Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices