- [Instructor] A color model is a way of describing
how colors can be reproduced,
and the two we will look at here are the most common,
RGB and CMYK.
RGB is an energy-based model and where you'll come across
that most obviously is actually right in front of you,
right now, on your screen.
RGB is said to be an additive model
as increasing the energy of its three primary colors,
red, green, and blue in various combinations
gives us around 16 3/4 million colors.
Let's take a look at that with these three sliders,
"Star Trek" style, of course,
but you'll have to make your own sounds.
And the resulting colors will be shown in the diagram above
which we'll now make completely black.
At the moment, all the three circles are black
as there is no light energy at all,
but if we increase the red slider
you can see how the top circle is becoming more red
until we hit its maximum energy.
Now we'll increase the green slider and you'll see that
as the intensity there increases, where it overlaps
we're heading towards yellow,
which is achieved when we reach both at maximum energy.
As we repeat that with the blue slider, you'll see
that the overlap with red is giving us magenta,
with green, cyan, and all three together
at maximum intensity gives us white light,
so that's the maximum RGB values.
And by the way hex colors
are just RGB values expressed using base-16,
which was a necessity back in the early days
of the web as six numbers we're faster to process than nine.
But let's switch now to CMY,
where the background is based on the white of paper.
What we're doing this time would be subtracting
from the paper's whiteness by adding ink.
And you'll see that once we meet full density on all three,
our secondary colors are red, green, and blue.
In the middle we have a weak black.
So now we'll take a look at four color plates of an image,
so you'll understand where the K,
which actually stands for key, comes in.
As we add ink to this paper
you'll see that each pass increases the number of colors
we see in the image.
Black boosts the range by adding depth to the darker areas
which changes our perceptions
of the other tones in the image.