Colour theory is one of the most important design aspects for an analyst to consider when building a dashboard. This post will explore the different aspects of colour theory, followed by a breakdown of the colour formats that are accepted in Tableau.
Colour Theory
Colour theory refers to the principles and techniques used to choose colours effectively in the design of a dashboard. Often a client will have a colour palette already selected for use within their style sheet, when selecting your own colour palette, there are 4 key considerations:
Contrast and Intensity: Use high contrast colours between the background and foreground colours to make text and other elements easier to read. Additionally, increasing the transparency of colours can make them less offensive to the end user.
Meaning and Semantics: Different colours can evoke different emotions and associations. For example, red is often associated with danger or urgency, while blue is often associated with calmness and reliability. Consider the associations behind a colour when utilising it in a dashboard.
Harmony: Use colours that work well together to create a cohesive and visually appealing design. One way to do this is to use a colour scheme, such as a monochromatic scheme (using different shades of the same colour) or a complementary scheme (using colours that are opposite each other on the colour wheel).
Accessibility: Make sure that the colours you choose are legible and accessible to users with different visual impairments. This includes choosing high-contrast colours for text and using colour-blind-friendly palettes.
By considering these principles and techniques, you can create a dashboard that is visually appealing, easy to read, and effective at communicating information.
Colour Formats
Tableau gives you many options in choosing colours for your dashboard. For example, by using the colour selector to the right of the screen, you can explore a range of hues and saturations. Exploring this section will allow you to choose a very specific colour. However, it is difficult, if not near impossible, to replicate this colour a second time using trial and error. In this situation, we are able to use the information provided in a format determined by a colour model. Tableau utilises two main different colour models, the RGB model and HEX codes - seen towards the bottom right of the colour palette below:
RGB Colour Model
In the RGB colour model, colours are created by combining different intensities of red, green, and blue light. Each colour channel (red, green, and blue) is represented by a value ranging from 0 to 255, with 0 representing zero intensity and 255 representing the maximum intensity. For example, the RGB colour code for red is (255, 0, 0), which means that the red channel is set to its maximum value of 255, while the green and blue channels are set to 0.
HEX Colour Codes
HEX colour codes are written as a six-digit code, using the letters "A" through "F" and the numbers "0" through "9," preceded by a pound sign (#). This is formatted into 3 groups of 2 digits, corresponding to the Red, Green, and Blue values of the colour in a #RRGGBB format. The two digits for each colour represent a value from 00 to FF in hexadecimal, which is a base-16 number system.FF represents the maximum value, corresponding to the decimal value 255, and 00 is the minimum value and corresponds to the decimal value 0. For example, the HEX colour code for red is #FF0000, which is made up of two digits for red (FF), two digits for green (00), and two digits for blue (00).
These models each produce similar information, presented in different formats.