So, now, why use a multi-hue sequential color scale?
If we are happy with a single hue,
why should we use multiple hues?
Well, there are a number of important reasons.
The first one may be just aesthetics.
It's possible sometimes that using multi-hue color scales,
the result is more aesthetically pleasing,
but that's not the only point.
Another one is that by going through different color hues,
we span a larger volume of the color space,
and by doing that,
we go to a higher set,
a larger set of colors.
In turn, this means that we can create a higher,
a larger set of discriminable colors.
Colors that can be discriminated among them.
So, in a way, we have higher resolution.
When we allow ourselves to span multiple hues in the HCL color space,
now we have a larger space,
and because of that,
we have a higher resolution, which is important.
Finally, and probably even more important,
we have that by going through multiple hues,
we can communicate two pieces of information at once.
We can communicate information about the quantity that is mapped to color,
but we can also segment areas that are mapped
through color into areas that can be very easily labeled.
I can say, so this is the red color,
this is the red area,
this is the yellow area,
this is the blue area, for instance.
Let me show you an example that makes this more clear.
Here is an image that is being generated with
a multi-hue perceptually uniform color scale to represent some astronomical data, okay?
As you can see here,
there are different regions,
each regions represent areas where the quantity is similar,
but since we are going through multiple color hues,
it's also very nicely segmenting these areas
into regions that are easy to label and even name.
I can talk about the red region,
the white-blue region, and the yellow region,
and the dark-black region.
So, I can actually name them.
This is not easy to do with color scales that use only one color hue.
Let me give you another example.
This is another quantity map mapped in the UK
with three different uniform color maps that have the same property.
They span different color hues,
but they're also perceptually uniform in terms of lightness.
As you can see, not only information about quantity is well-represented,
but also information about regions.
I can segment regions according to different hues.
