I’ve been given a solid black design that I have to print in a manner which is view-able through 3D red-blue stereoscopic glasses (Old school 50’s cinema type)
When I offset the design into Red-only and GreenBlue-only channels, it gives the required effect. However, when I then convert colour space mode in Photoshop to CMYK for printing the colors become massively desaturated, the blue more than the red.
The CMYK version is spot on to how a physical print looks. However, the color is so different it completely kills the effect while wearing glasses. I was expecting to have to do some color space wrangling but I have no idea how I could alleviate this issue as it’s not usable. Is it possible to print a cyan as saturated as in the RGB image? Is this a colour space issue or an inking issue?
Sadly, these very saturated colors can’t be reproduced in CMYK.
You could try to make the image in CMYK mode, where you make sure that the red is CMYK(0, 100, 100, 0) and the cyan is CMYK(100, 0, 0, 0). Don’t make it in RGB and convert to CMYK as it might pollute the clean inks.
I believe that it’s important to only use solid colors (all CMYK values 0% or 100%). Halftone screening might fool the human eye, but I’m not sure if they will fool colored glass. The glass might not be able to filter the resulting color, but only the individual inks.
Even using two inks for the red might be problematic if your artwork has 8-bit transparency as there will be halftone dots of magenta and yellow along the lines which might not be filtered fully by the glasses.
Your best option might be to look into printing your work with two spot colors. You need to get your hands on a physical color book with samples, so you can test which colors will work with the glasses.
The most used system of spot colors is Pantone, but you should ask your print house about what they recommend. There are Pantone colors which are way more vivid than achievable with CMYK, but there is no Pantone cyan quite like RGB cyan. I don’t think it’s physically possible to achieve that color on paper.