Color improves a chart’s aesthetic quality, as well as its ability to effectively communicate about its data.
Categorical colors help users map non-numeric meaning to objects in a visualization. These are designed to be visually distinct from one another. The Spectrum categorical 6-color palette has been optimized to be distinguishable for users with color vision deficiencies.
Diverging colors also have numeric meaning. They’re useful when dealing with negative values or ranges that have two extremes with a baseline in the middle. Diverging palettes are a pair of 2 gradations of colors that meet in the center.
Spectrum has 3 palettes designed for use with diverging data:
Categorical colors are not ordered. Use these for categorical scales. Do not use these for ordinal, interval, or ratio scales.
Sequential colors are ordered. Use these for ordinal and interval scales. It’s also acceptable to use these for ratio scales. Do not use these for categorical scales.
Diverging colors are ordered. Use these for ordinal and ratio scales, especially when there is a meaningful middle value. These may also be used for interval scales. Do not use these for categorical scales.
Instead of giving each item a categorical color, encode them with a secondary dimension — ideally, one with few values. An exception is when the chart is paired with other charts that use color for the same categories.
Use color to separate items into categories.
Don't use color to separate items.
It’s best to use fewer than 6 colors in the Spectrum categorical color palette. Categorical colors become more difficult to comprehend starting at 6 colors, and extremely difficult to understand at 12. If you have a need for more than 6 colors, try alternative visual encoding, such as position, which can be easier to read and scales better.
Sequential colors are optimized for numeric meaning. Using these colors for dimensions can undermine the numeric association and lead users to misunderstand visualizations.
Categorical colors are optimized for maximum differentiation. Using them for sequences (ordinal, interval, or ratio scales), even when arranged by hue, makes it more difficult for users to understand.
Dark colors can often carry a subconscious association with density. Use a palette that transitions from light to dark as the numbers get larger.
Diverging colors are designed to be balanced from a central midpoint. When the maximum value in your data is not the same distance from the center as your minimum value, alter the palette to reflect those values. It’s best to crop out unneeded colors; don’t distort the palette to make them fit.
Crop diverging colors.
Don't distort diverging colors.
It’s important to be consistent with color when there are multiple charts in the same view. If a color is used to represent something in one chart, all other charts should echo that relationship.
|Dec 01, 2019||1.0.0|