Complementary colours and how they work

Colours can be complementary (opposite) or harmonious (‘analagous’) depending on their relative positions on the color wheel, a visual aid which places colours on a continuous spectrum within a circular ‘wheel’. Adobe has a very clever interactive colour wheel which shows how this works and how you can use it to compare or ‘plan’ your colours.

So for example, the complementary colour of blue is orange, and this image shows how that can look. (You may be used to thinking of yellow as the complementary colour to blue – I do – but technically it’s orange.

In principle, complementary colours make for a strong contrast and an effective image. In principle. However, my take on this is that that colour contrast on its own is rarely enough. If the blue and orange tones are similar in brightness then there may not be all that much actual visual contrast. You’ve ticked the box and it hasn’t worked.

What’s going on in this photograph is more complex. The dark blue sky and orange-lit cathedral have complementary colours but they also have contrasting luminance values. The sky is dark, the cathedral is bright. That’s why the colours in this image leap out – it’s not just a colour contrast but a brightness contrast too.

Colour gets its strength from contrasts. Not just colour contrast, but luminance and saturation contrasts too. All three of these can work on their own, but can be even more effective when used together.