# Quantitative Color Scales

## The Desired Properties of a Quantitative Color Scale

A quantitative color scale is designed to represent quantitative information. It has 2 main properties: **uniformity** and **discriminability**.

### **Uniformity**

This means that the color scale must be perceptually uniform i.e. value difference = perceived difference\
![](https://612062878-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M5-0RG_uqhxyMNjpMUW%2F-M5-0SvQ45Rarxg8L2lA%2F-M5-0Uo-vStxhnJlkZeE%2Funiformity.PNG?generation=1586990819422458\&alt=media)

To create a uniform color scale, we must start with a **single hue**/color and then **uniformly vary the luminance**/lightness, keeping the **saturation constant**.

### **Discriminability**

This refers to being able to represent as many distinct values as possible by having as many distinct colors as possible.

## Multi-Hue Color Scale

The previous subsection depicted a single hue color scale. We can also use multi-hue color scales, starting with a dark color and ending with a light color, with several other hues in the middle, in uniformly increasing order of lightness.

![](https://612062878-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M5-0RG_uqhxyMNjpMUW%2F-M5-0SvQ45Rarxg8L2lA%2F-M5-0Uo1Nz8MCqR7i10Y%2Fmulti-hue.PNG?generation=1586990819491263\&alt=media)

Some common reasons to use multi-hue color scales:

* **aesthetics**
* a larger set of colors **increases discriminability**
* allows us to **communicate two types of information** at once: we can depict quantity and also perform segmentation into regions that can be easily labeled (ex. the red region, the blue region, the yellow region etc.)


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