Sure you can. Red rose in a field of green for example. Human eyes evolved to see the colours the way they do precisely because they were working in a world where nearly everything is colourful and some things needed to stand out.

A field of green is not colourful.

> Possessing prominent and varied colors.

Have you looked at a field recently? Spot the flowers: https://wallpapercave.com/field-of-flowers-wallpaper - I'm not sure what you call colourful; but I call those colourful. The flowers are still hard to miss. The colour makes them more obvious.

If you want a more academic source; try https://www.stat.auckland.ac.nz/~ihaka/courses/120/Lectures/... slides 13 & 14. Colour isn't some random distraction, the human vision system uses it to help decide what to focus on. Then you get things like peacocks where they go all in on using colourful visualisations to attract attention.

> When everything is colourful you can't use colour to stand out. It's very simple. Obvious even.

Why not? Different colors stand out. Even gray on black does. They are just not colorful.

Look at this painting - [0]. Are you telling me the red tone doesn't stand out?

[0] - https://largemodernart.com/products/original-abstract-art-oi...

Come on, I think you know what we mean and are just being pedantic.

Which colour stands out here? https://business.cap.co.uk/sites/default/files/styles/cap_ex...

I seriously don't know what you meant by the following:

> When everything is colourful you can't use colour to stand out. It's very simple. Obvious even.

My example is clearly a colorful painting, very vibrant, yet certain tones stand out. What you said is literally wrong. It's neither simple nor obvious. Spell out what you meant. Your counter example isn't obvious either.