what colour is indigo?

Seems to be a lot of people typing

what colour is indigo

into google. Why all the fuss about indigo?

In case you are one of those people I can tell you that in the spectrum indigo was generally considered to be associated with wavelengths in the range 420nm – 450nm though many would argue that it is not in the spectrum at all and that light below about 450nm is considered to be violet. Have a look at my earlier post about why indigo is generally not considered to be in the spectrum by modern colour scientists.

In terms of RGB (sRGB for the techies) it can be approximated as R=75, G=0, B=130 and this looks like this:

Though of course, the RGB on-screen representation is not the same colour as the indigo in the colour spectrum since every colour in the spectrum is outside the gamut of your RGB display and therefore cannot be properly shown.

The word indigo is named after the blue colorant obtained from plant indigofera tinctoria.

3 thoughts on “what colour is indigo?

  1. Indigo is my favourite colour. And it can be fully described. It is only seen as difficult to describe as it is between blue and violet of the rainbow and so this can be quite a range. In other words, it is the colour of the sky. Think about how the colour of the cloudless sky in winter is very different to the colour of the cloudless sky in the middle of the day in summer. All is indigo. My favourite indigo is of course the midday sky of summer! So in conclusion, indigo is easy to describe but hard to pigeon-hole as it has a huge range. (Lilac flowers are close to indigo as they also come in a variety of colours in the range).

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