Perceptually Uniform Color spaces

Why do we need perceptually uniform color spaces? Because working with color in code is different than working with color in traditional design tools. Traditional tools encourage designers to think in manual workflows with the color picker as the primary way of choosing color combinations. In this scenario, designers use their eyes to decide whether a color is right or wrong, and the RGB values play no role in this decision. Code is different, because programming languages encourage designers to think about colors as numbers or positions within the chosen color model. This skill is hard to learn if the numbers do not correspond with the output. Perceptually uniform color spaces allow us to align numbers in our code with the visual effect perceived in our viewers.

In some cases, perceptually uniformity is essential. A simple example like wanting to choose a random color to be readable against a dark background can be hard in irregular color spaces, because colors with the same lightness or brightness vary greatly in how bright they appear (blue and yellow both have 100% brightness in HSV, but blue is much darker than yellow). One would need to do all sorts of calculation based on the chosen hue to make the random colors equally bright.

If designers are not aware of this, it can even lead to misleading designs. A good example is the use of continuous color scales in data visualization. For certain map types, designers use a gradient to color geographic areas to reflect the value of a data point, and the user can compare colors between regions to get a sense of the data. If the designer created the color scale in a regular color space, the perceived colors will be different from the data points reflected in the color values. To have the design show the actual data, a perceptually uniform color space is required.

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