Hi, welcome to a new model
which is a follow up of the previous one.
So, we're still talking about color.
But with the main difference that in the previous module,
we focused on perceptual issues and color spaces.
Now, with the knowledge acquired in the previous module,
we can talk more about how to actually use color in visualization design.
Before I do that,
I want you to recall a few important concepts from the previous module,
that's it's important for you to keep in mind as we move through the rest of this module.
So, the first one is the idea that every color can be described by three main components,
the trichromacy theory of color.
So, that's important, every color can be described in different color spaces if you want,
but always with three main components.
Then, we talked about the problem of perceptual uniformity.
When you specify colors for data visualization,
it is very important to keep in mind that we need to
specify colors in a uniform color space.
Why? Well, because as you will see,
we typically want to create color palettes that have certain properties,
and some of these properties require that for instance,
some colors have the same lightness value or the same saturation and so on.
If we can't assure that these values are constant from the perceptual point of view,
we can't really create effective color scales.
Finally, we will keep using the important concept that color can be
described through three very intuitive and usable axis or parameters.
The first one is hue which defines the color name,
if you want the type of color.
The second one is saturation which defines the vividness or colorfulness of the color.
The last one is luminance which is the amount of
light or brightness that the color is emitting.
Okay, so let's go back to the most important question of this module.
How do we use color in visualization?
What is its main purpose?
Well, we can define color use in visualization in
a somewhat abstract way as being used for two main purposes, two specific purposes.
The first one is to quantify.
We want to use color to map
quantities to color so that when we see colors in a visualization,
we can go back to quantity.
That's purpose one.
Purpose two is label,
we want to be able to label data and objects in a way that we can
recognize and recall what type of object some object is when we see this color.
Let me show you a couple of examples.
So, the first one as we said is going from perceiving
color to linking the color to the concept of quantity.
Here, is an example.
There is a map where
