This web app runs with the help of Name that Color by Chirag Mehta and uses the NBS/ISCC Color System as a color dictionary.

Why cmy-OK?

Can't tell if your rendered sky is too purple? Grass too blue? cmy-OK is meant to help colorblind designers identify colors as seen and understood by non-colorblind others.

How to use?

1. Click on the color-input field at the top of the page (or at the lower-center if on the index page) to open up a mini-window. 2. Choose a color either by clicking one within the field, or clicking the eyedropper button under the field and selecting a pixel anywhere on your screen. You may also input by value and switch between RGB, HSL, and HEX by clicking the lower part of this mini-window.

No I mean, why the name?

Oh. Well, CMYK refers to the four ink plates used in some color printing: cyan, magenta, yellow, and key (black). This web app is named cmy-OK because your file is more likely to be ok after using this. But I agree, it's not a great name because cmy-OK is actually only usable on digital images and colors.

More resources

Color-Name Dictionaries
Name that Color, developed by Chirag Mehta
Encycolorpedia