Sunday, July 26, 2015

Rainbow in infra-red

Most usually, when processing infra-red photographs, they are converted to black and white; basically because infra-red doesn't have any colour that we can see. In black and white, white means lots of infra-red, and black means little or none - it's a convenient representation of something we can't actually see.

However, our cameras have sensors that capture light in three channels; red, green and blue. Even values of infra-red radiation get captured in these three channels though infra-red wavelengths have very little red and no green or blue at all. So, when we process an infra-red picture, it is still made up of red, green and blue data and, if we produce a picture from these three channels of data, it is usually known as a 'false colour infra-red' - which can look quite unnatural; hence why black and white is often favoured.

However, when a rainbow appeared today, I wondered how it would show up if photographed in infra-red and the colour channels were retained. So, because every man woman and child in the world are dying to know the answer to this question, here it is:
Rainbow over Oxford - false colour infra-red photograph

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