Principles of colour

posted under by Philip Howlett
Light is such an important part of film, and that's why it's important to understand how light works. Reading the "principles of colour" on the cybercollege website, I was reminded of a lot of things I learned in science at school.

White light is a combination of all the colours in the spectrum. This can be illustrated by shining light through a prism. Nothing new there. What I didn't know is that when cyan, magneta and yellow are combined, they create black. This black can sometimes be described as 'muddy' and to overcome this the colour printing process CYMK was created. I've seen this abbreviation before in Photoshop, but I've never understood what it was. I now know that the K stands for black. I also didn't realise that when you use a filter to cover a light that it's actually blocking colours of the spectrum. I always presumed that a translucent red filter was just turning light red. The science behind is that it actually blocks every other colour in the spectrum, just allowing red through.

Red, Green and Blue are the primary colours of television. I already understood this as I've used a lot of visual equipment which take advantage of RGB connections. The reason that only these three colours are needed is that they can be combined to create many other colours. When a video is recorded the colours are separated, then when the video is played on a television the colours are combined.

Simultaneous contrast is another concept I've been aware of, but never knew it was a technical term. I'd noticed that on certain televisions the picture could look better than on others. For instance a television with a black and shiny frame can help to produce a better contrast in the picture than one with a white frame. This has been taken advantage of by the Philips "ambilight" tele's which change their back light colour depending on the colours on the screen.



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