i just did a google search for “rgb equivalent of 100c 100m 100y”
—and after reading this interesting post of yours—
it seems there may be one small and somewhat simple consideration that’s getting overlooked in this discussion. it may help clarify for some. —the Keep It Simple approach is often applicable even when dealing with color formula — bottom line being the intended end-use of the color formula you are creating. Any color-critical task is always going to be more clear-cut and you will pull-out-less-hair if you keep in mind the question: is my intended end-use of the color going to be ON-SCREEN or ON-PAPER[and/or other print substrate(s)]. Trying to find some kind of utopian hybrid color or color space between RGB and CMYK is always going to be more likely to cause frustration. i suppose my rant/response stems from my search which developed from trying exercise some very basic print-color-control when using a free graphics progam such as GIMP (which does not create CMYK files) when i don’t have my obvious favorite Photoshop, but the files created are going to be printed with CMYK inks. Well, actually in my case I simply want to omit the use of any black ink by replacing all values in the image that would require black ink to be created with the RGB numbers/percentages that equate to a dark-grey virtually black that can be created with c100, m100, y100. So my end-use is somewhat strange (RGB for printing), while many folks are probably trying to to take CMYK-to-RGB for the sake of accurate on-screen display. Photoshop is the right tool for this little task I’m trying and it makes it really simple, but maybe i just enjoy the challenge of trying to figure out if some simple things like this can be done with the free program(s).