Color Theory Which colours is white light made of? Color Mixing Color can be perceived either from 1) a luminous object (TV, monitor, projector) using the Additive Approach 2) reflected pigment or ink (printouts, materials) using the Subtractive Approach Additive Color Model Used by luminous objects ex. Computers, TV, projectors When light energy is added, a color appears brighter The additive primary colours are (RGB): – Red – Green – Blue Secondary colours produced are (CMY) – Cyan – Magenta – Yellow Different percentages of red, green, & blue light are used to generate different colours White light is created when Red, Blue and Green are mixed together There is no way of making black by adding red, green and blue light sources, the screen must be black to start with. http://dev.physicslab.org/asp/ap plets/additivecolors/default.asp Our Eyes Our eyes use the additive colour approach, but how do we see colour if all wavelengths are coming in from the sun (white light)? Objects absorb all colors except the color being seen, which is reflected White light Green Surface White Light reflected White light Green Light reflected Blue Light reflected White light White Surface Blue Surface White light Red Light reflected White light No Light reflected Red Surface Black Surface Objects absorb all colors except the color being seen, which is reflected White surface = all wavelengths (blue, red, green) are being reflected Black surface = all wavelengths are being absorbed. Red surface = blue and green wavelengths are absorbed, red is reflected Green surface = blue and red wavelengths are absorbed, green is reflected. DEMO Questions, why are clouds white? Why is it not a good idea to wear black in the summer? Subtractive Color Model Used in the print media ex. inks, fabrics, paints, crayons, etc. When more color is added, a color appears darker The subtractive primary colours are (CMY): – Cyan – Magenta – Yellow Secondary colours produced by CMY colours are – Red – Green – Blue What do you notice about the primary & magenta & yellow Different percentages of cyan, light are used tosecondary generate different colours colours? There is no way of making white by adding CMY colour sources, the paper/canvas must be white to start with. Computers DON’T use the subtractive theory. 16 Because printers work on subtractive colour system and computers don’t, it’s hard to reproduce the same picture. Cookie Wheel Colour Blindness 1 out of 10 men and 1 out of 200 women have some type of color deficiency. The most common type is mistaking red and green. The second most common type is mistaking blue and yellow Blind Spot – not just on cars!