I picked up a low pressure sodium lamp and am working on a Halloween demonstration. I’m hoping to make a display that appears one way under normal light, but looks totally different under the monochromatic 589nm sodium vapor light.
So basically, I’m looking to generate a color wheel where I pick a shade of gray and get a list of colors that would look that gray under sodium vapor light.
…I feel like there must be a Python library for thing or something…
So I’m really not sure how this works anymore but if you figure out which frequencies alias you can use https://academo.org/demos/wavelength-to-colour-relationship/ to do a conversion.
Hmmmmmmmmm… From a high level perspective you need to know the reflectivity of your combined pigments at that wavelength. If it’s the same, they will look the same.
I don’t know of anything easy you can use, but would suggest trying to find reflectance curves for each pigment you have available and making combinations that subtract to the same value at 589nm, or since 589 should be basically yellow, make up some colors where Y is constant and you change the ratio of C to R and try them out?
That’s true! Using RGB alone will not be enough to calculate this! Two materials that might appear equally yellow under white sunlight may appear different shades of yellow under sodium light. Technology Connections did a great video about the difference: https://piped.video/watch?v=uYbdx4I7STg
edit: he starts talking about sodium light in particular at 11:14
Is there an equation for this? Like y = f(x) where y is your choice of gray and x is your color. Maybe you can empirically find “f” by fitting randomly created “x” with the resulting “y”.
If “f” can be approximated and maybe there’s something special about it so that you can find the inverse. Otherwise, you could always just generate a bunch of “x*” again, feed through “f”, and see whether the output “y*” matches your chosen gray.
Would it count as easy to make the colors in a photo editing tool (picking things of the same value and saturation but different hues) and then converting to the CMYK designation?
