What is the difference between color addition and color subtraction?

Answer 1

This is a lengthy subject. Here's a short answer with a link to follow up on.

The 3 primary colours of light (not to be confused with grade 4 art lessons and paint pigments) are red, blue and green. Project two of these colours on a screen and overlap them; the overlap area will be the complEmentary (not complImentary) colour, which can also be called the subtractive colour. Thus we can make 3 complementary colours by varying the combinations. Overlap all three and you get white. You now have seen 3 secondary/complementary/subtractive colours (magenta, cyan and yellow) in the overlap areas.

If you place a subtractive coloured filter in a beam of white light, it passes its own colour (which is made up of two primaries, remember) and blocks the remaining colour, in the white light beam. For example, the subtractive colour yellow is made up of the primaries red and green. They pass through, but the other primary does not, hence it is subtracted. What is subtracted? See the first sentence of this explanation. I hope you guessed "blue".

The practical application of this in Photography would be in colour printing. What can be confusing for the beginner is that the adjustment in filtration is the opposite for printing negatives that you would do for printing transparencies!

Here's the link:

http://www.rgbworld.com/color.html

Answer 2

Additive and subtractive colours are exactly as the name implies. Our eyesight requires light to see with and to differentiate colour. If we have all colours removed (subtractive), we get black. If we have all colours present (additive), we have white.

When we look at a plain piece of paper, we see all colours present so it appears white. But when we add ink to it we are filtering out the colours that are being reflected back to us from the white lightsource.

Additive colours are those that deal with light. With no light we have black of course. Using the primary colours of Red, Green and Blue in different combinations and proportions, we can create almost every colour and shade. Combine them all and white light results. Secondary colours made from equal amounts of two of the primaries are Cyan (turquoise) Magenta (pinkish-purple) and Yellow.

This method of colour mixing is how your TV and Computer Monitors work.

Subtractive colours almost always deal with physical media such as paints, dyes and others. Primary colours for subtraction are Cyan, Magenta, and Yellow, and their secondary colours are Red, Green and Blue. The way it works in this case is a little trickier to understand, but if you think of it in terms of a colour MISSING from the group, or subtracted, it will be easier to visualise. For example, looking at an otherwise white piece of paper with a patch of Cyan ink on it, you are actually seeing white with Red removed - similarly, the Yellow removes the Red and the Magenta removes the Green. Again, with all three colours removed, you end up with nothing...Black.

Typical applications are printing inks (magazines etc), paintings, modeling clays etc. The primary colours used for subtractive purposes are cyan, magenta, and yellow - and these are defined by the printing industry as CMYK (with black being represented with the K). Mixing the colours with white or black will brighten or darken the results respectively.

It should be noted that media like crayons or markers would be classified as a filter, thus would work as subtractive and additive (to a small degree) due to the variable transparency on the white background.

Note: Original thinking in the 1800's proposed that the primary colours be Red, Yellow and Blue, (making Orange, Green and Magenta secondaries) but today's current standards are the RGB model.

Answer 3

So the easy way to remember the difference between additive and subtractive color mixing is that additive color mixing is what happens when we mix lights of different colors whereas subtractive color mixing occurs when we mix paints or other colored material.