How do you calculate shade value so two different colors share

how do you find the gray equivalent of a color. say i had a blue in CMYK. how do i find the gray version of that color?

>>254507
doubleclick the color in illustrator and pulldown to grayscale

>>254507
No easy answer. Almost any software (including Ai) will give you the wrong answer by default. Most software will give you a very wrong answer (e.g. sRGB averaging or GIMPs "lightness"), other software will give you a less wrong answer (using ITU-BT REC. 709), but in the end it doesn't mean the colors will actually come out equiluminous from your printer.

You can compute it if you have the color-profile of the printer.

>>254679
>You can compute it if you have the color-profile of the printer.
how?

thanks for the informative post

>>254702
there is almost no way to obtain a color-profile other than to measure it yourself with a colorimeter. Some (but this is pretty rare) manufacturers give color-profiles for their printers, but those are also only really accurate if you use the type of paper they've been created with.

Once you have it, you can create a document with that colorprofile in krita or sth and probably go from there, IDK, the steps aren't quite clear to me right now, but there's probs a way.

>>254495
you make an educated guess then goto the press check