---
title: "CET Perceptually Uniform Colour Maps"
author: "James Balamuta with material heavily taken from Peter Kovesi"
date: "`r Sys.Date()`"
bibliography: cet.bib
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{CET Perceptually Uniform Colour Maps}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

The [`cetcolor`](https://cran.r-project.org/package=cetcolor) package is designed
to bring to _R_ the colour maps created by [Peter Kovesi](http://peterkovesi.com/projects/colourmaps/) 
in @ARXIV:Kovesi:CETCOLORMAPS. These colour maps avoid points of locally high colour contrast 
leading to the perception of false anomalies in your data when there are none.
The colour maps have been designed to avoid this phenomenon by having uniform 
perceptual contrast over their whole range.

This vignette attempts to summarize information presented at <http://peterkovesi.com/projects/colourmaps/>.

## Supported Colour Maps

There are 56 supported colour maps organised according to the attributes: 

- Linear
- Diverging
- Rainbow
- Cyclic
- Isoluminant
- Colourblind

## Organisation of Colour Maps

The colour maps have a short name and a long name. The shortname is meant
to use while graphing and the long name is meant to understand how the
color map was generated. 

The shortnames are created by having at the start one or two characters to indicate whether
the map is: linear (l), diverging (d), rainbow (r), cyclic(c), isoluminant (i) or colour blind (cb).
From there, a number is appended to the end. For example, the linear greyscale is 'l1',
the heat colour map is 'l3', and the blue-white-red diverging map is 'd1' and so on.
Below, you will see each of the sections of colourmaps in a visual catalog
with their shortnames.

Each colour map is also assigned a "long" named as follows:

```
                    linear_kryw_5-100_c67_n256
                      /      /    |    \    \
Colour map attribute(s)     /     |     \    Number of colour map entries
                           /      |      \
     String indicating nominal    |       Mean chroma of colour map
     hue sequence.                |
                              Range of lightness values
```

Moreover, the colour map name may contain cyclic shift information as well
as indicating whether it has been reversed by a flag.

```                                              
              cyclic_wrwbw_90-40_c42_n256_s25_r
                                          /    \
                                         /   Indicates that the map is reversed.
                                        / 
                   Percentage of colour map length
                   that the map has been rotated by.
```

## Colour Maps

Please note, some colormaps have been "deprecated" from the initial release.
As a result, these colormaps do _not_ have a shortname and, thus, their 
long-name are displayed. In a future release, we will likely remove these
color schemes.

### Linear

```{r fig.width = 7.5, fig.height = 8}
library("cetcolor")
display_cet_attribute(attribute = "linear")
```

### Diverging

```{r fig.width = 7.5, fig.height = 5}
display_cet_attribute(attribute = "diverging")
```

### Rainbow

```{r fig.width = 7.5, fig.height = 3.25}
display_cet_attribute(attribute = "rainbow")
```

### Cyclic


```{r fig.width = 7.5, fig.height = 4}
display_cet_attribute(attribute = "cyclic")
```

### Isoluminant


```{r fig.width = 7.5, fig.height = 3.25}
display_cet_attribute(attribute = "isoluminant")
```

### Overall

```{r fig.width = 7.5, fig.height = 12}
display_cet_all()
```