FREQUENTLY ASKED QUESTIONS (faqs)
- I am not yet a member, can I come to the next Colour Group Meeting?
- Where in the spectrum does brown come?
- Is black a colour?
- I am giving a talk at a Colour Group Meeting - What facilities are available at Centenary Building, City University?
- Are red, yellow and blue the three primary colours?
I am not yet a member, can I come to the next Colour Group Meeting?
Answer: Most Colour Group meetings are free and open to all. Occasionally you may need to register - check on our meetings page and if it doesn't mention registration you can just turn up. You will be very welcome.
Where in the spectrum does brown come?
Answer: Brown is "dark Yellow", so in isolation it looks yellow. For anything to appear brown, it needs a reference background of higher luminance.
These two words are displayed in exactly the same colour: it is the background that makes the difference: brown yellow.
Could you please settle our argument over whether black is a colour or not. Please reply soon before we fall out and hurt each other - Two bored Observers
Answer: You're both right: depending on which side of the perception/physics fence you're on! In terms of Perception, Black, like Greys and White, is an achromatic colour: a colour without hue and saturation (or "strength"). If the term is intended to be Physical (physical and psychophysical concepts are often confused) and Black refers to a total absence of visible radiation (light) then, if there is no physical stimulus, there can be no physiological response: no response-> no perception-> no colour.
I am giving a talk at a Colour Group Meeting - what facilities are available at City University?
Answer: It depends on which theatre is booked. There will be one whiteboard and one screen and usually a projector for PowerPoint, etc. You are advised to bring your own laptop although a PC is present it is usually password protected and not easily useable. 35mm projectors are not provided and an overhead projector may not be present though a webcam system is. But we suggest you contact the organiser of your meeting.
Are red, yellow and blue the three primary colours?
Answer: There
are two sets of primary colours: red, green and blue are the additive
primaries used in colour vision, colour measurement, television sets
and computer monitors (because they correspond to the sensitive elements in the human eye), but cyan, magenta and yellow subtractive primaries used in colour photography and printing. A cyan filter transmits
green and blue light (absorbing red), a magenta filter transmits red and blue light (absorbing green) and a yellow filter
transmits red and green light (absorbing blue). Perhaps this diagram will make things clearer: on the left (additive mixing) the three primary colours are projected onto a screen (note the coloured shadows and the white at the centre) and on the right (subtractive mixing) the colours are produced by laying on pigments (note the black at the centre).
Sometimes people use the words meaning what are here defined as the subtractive primaries, but this leads to confusion.
