Page 101 - Graphic Design and Print Production Fundamentals

Graphic Design 89
brighter colour is to be expected. Continuing on: combining green and blue gives us a light blue that we
call cyan, while the combination of red and blue produces magenta.

Since each of these colours is produced by subtracting one of the additive primaries from the full
complement of white light, we refer to this colour set of cyan, magenta, and yellow (CMY) as the
subtractive primaries. Each of the subtractive primaries acts as a filter for its complementary colour
in the additive primary colour set. Cyan absorbs all red light, reflecting only green and blue. Magenta
absorbs all green light, returning only red and blue; while yellow absorbs all blue light and reflects back
only red and green. What colour would you see if you shone green light on a magenta patch?

Just as we can produce any colour sensation in the transmission of light by mixing the appropriate
quantities of red, green, and blue, we can produce the corresponding colour sensation when we put ink
on paper by absorbing the necessary portions of the visible spectrum so that only the required amounts
of red, green, and blue are reflected back. This is how cyan, magenta, and yellow work as our primary
colours in the printing environment, and why we also call them the reflective primaries.

Opponency

The second half of the role that our human physiology plays in the observer’s part of the colour event is
the concept of opponency. Our eyes’ tristimulus response (a response to the red, green, and blue portions
of incoming light) is the input, but the interpretation occurs when we map that input to a location in
a colour space determined by three axes of opposing sensations. We have a built-in colour map where
we define our colour perception by identifying the perceived colour based on its degree of greenness to
redness, blueness to yellowness, and darkness to lightness.

These three pairs of opposites — green-red, blue-yellow, dark-light — are the fundamental guide posts
we use to position any colour we perceive on our internal colour map. These opponent colour pairs are
exclusive colour entities, occupying opposing ends of the range of our interpretation. Unlike a yellowish-
orange or a reddish-purple, we cannot imagine a colour having the properties of red and green or blue
and yellow at the same time.