Have you ever chosen a key colour for your interior by selecting it from your curtain or upholstery fabric but been disappointed with the colour match when you saw it in situ? If so, you may have been tricked by optical mixing.
The colour you chose may well be an exact match to the one in the fabric but our eyes tend to blend colours which sit next to each other. Georges Seurat the post impressionist painter used this effect to his advantage in order to blend colours, a technique called pointillism.
Analogous colours (colours next to each other on the colour wheel) are particularly prone to this effect, whereas complimentary colours (opposites on the colour wheel) don’t blend but strengthen each other making them appear to vibrate.
So, rather than pick a colour at close range from a swatch on a mood board, remember to stand back and choose a colour that matches the perceived or blended colour.