Given a color palette, is there a formula or are there rules or methods to determine if an additional color will fit with this scheme?

For instance, if I wanted to add some vegetation (grass, trees, etc.) to the following picture:


What hue / values of green would fit with the underlying scheme of the picture?

How could I determine those values other than by trial and error?

  • 2
    Most artists merely pick a color they feel will work best. What you're describing sounds like "paint by numbers", which is fine if that's the goal. It's just not customarily how original art is created.
    – Scott
    Nov 1, 2021 at 10:12
  • @Scott Perspective has some clear geometric rules, it doesn’t mean you have to follow them to the letter. However, if you can only cheat if you know the rules… I suppose the same applies to colors… Nov 1, 2021 at 11:07
  • The Masters never used any grids, yet they are referred to as "The Masters" :)
    – Scott
    Nov 1, 2021 at 19:20
  • Perhaps they did so implicitly or in a subliminal way? Nov 1, 2021 at 21:53

2 Answers 2


There are no actual rules as such for colour selection. It's more or less a subjective choice. There are no colour police and you are free to combine any colours you like. However there are several online tools you can use if you need help. You don't need to work out any complex formulas for this. These tools can do all the maths for you.

For example

Green is complementary to red on the colour wheel, because red and green are opposite each other on the wheel.

Let's take some of the colours sampled from the example image you posted. This was actually done automatically using a feature on the website to upload an image and automatically sample the colours.

enter image description here

The red here is #D95D41

If you type that colour value into the Adobe Color website you can generate some complimentary shades of green.

enter image description here

Here I've chosen the "Complementary" colour harmony rule, and set the colour controls to HSB.

It's possible to move the Saturation and Brightness sliders to create any number of shades of green which are complementary to that red colour

enter image description here

Note: I have no affiliation with Adobe or connection with that site, I merely included this site as an example. There are several other websites which offer similar functionality.

  • Sounds like a pragmatic solution. Thank you! Nov 1, 2021 at 13:58
  • Do note that Adobe Color does not use the 'true' HSB colour wheel, but a manipulated version that compresses greens in favour of yellows, reds and oranges. This is shown by the fact that the two example colours you show have H values of 11 and 158 degrees, which is definitely not 180 degrees difference. </nitpick>
    – Vincent
    Nov 1, 2021 at 14:12
  • More nitpicking from me. Who says having a green which is complimentary to the red is even desirable? 🤓 Here are four different choices for the green. The one in the bottom is the one Adobe suggests. Should it be obvious to me that it's better than the other three? Not criticizing the answer really. Just want to point out that choice of color is really subjective and not easily put into formula.
    – Wolff
    Nov 1, 2021 at 17:04
  • 1
    @Wolff - sure but if you don't know what colour to choose or are not confident making a choice, then it's as good a way as any! So, why not? Yes, it's obviously only a suggestion, and not a rule as I mentioned already. Also the OP did actually ask for a green colour.
    – Billy Kerr
    Nov 1, 2021 at 17:17
  • Yes, I guess so. Perhaps one could make a semi-random palette generator which doesn't follow any rules as such, but simply presents some choices. 🤔 It can sometimes help to see a random suggestion rather than finetuning sliders yourself. I just feel Adobe Color and other palette generators gives us the "safe" choices and makes sure every design in the world sort of follow "the rules". There are in fact almost infinite possibilities.
    – Wolff
    Nov 1, 2021 at 17:23

The color selections cannot be numerized. The colors of the items to be inserted depend on their roles. Imagine 3 scenarios:

  1. The running group runs only because there's a playfyl competition who reaches first the gigantic plate full of big fresh fruits in front of them. Their a little hulking pet in the background also tries its best, but seemingly the woman will be the winner.

  2. There's a beautiful blossoming garden. Some creatures are running there, but they do not get nor should get much attention in the middle of the glorious mixture of trees, bushes and flowers.

  3. Three persons run to get away. A beast tries to catch them. The landscape doesn't offer any places to hide, only grass and occasional small bushes.

If you expect a set of colors which do not at all look offensive nor tepid when compared to existing colors which are quite mild (except the yellow hair) you find them for example with Photoshop:

enter image description here

  1. Turn your image to Lab Color Mode
  2. Set your color picker to sample all layers and let it make a small area average, say 3x3 pixels or point sample
  3. Insert Hue/saturation adjustment layer
  4. Insert a layer mask which allows the adjustment layer to affect only a part of the image. The mask is formed automatically if you have an active selection when the adjustment layer is inserted,
  5. Adjust the hue slider. Pick colors with the color picker. You get also RGB values.

Adjusting hue doesn't change the apparent colorfulness nor brightness in Lab mode. In RGB mode the result is somehow much more irregular, but it can work, too.

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