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## Color tables

A color table is a set of colors that is used by certain plots to color variables. Color tables can be immensely important for understanding visualizations since changes in color can highlight interesting features. VisIt has several built-in color tables that can be used in visualizations. VisIt also provides a Color table window for designing custom color tables.

Color tables come in two types: continuous and discrete. A continuous color table is defined a relatively few color control points defined at certain intervals in the color table and the gaps in between the color control points are filled by smoothly interpolating the colors. This makes continuous color tables look smooth since there are several colors that are blended to form the color table. Continuous color tables are used by several plots including the Pseudocolor, Streamline, Tensor, and Vector plots. A plot that uses a continuous color table attempts to use all of the colors in the color table. Some plots that opt to only use a handful of colors from a continuous color table pick colors that are evenly distributed through the color table so that the plots end up with colors that still somewhat resemble the original colors from the continuous color table.

A discrete color table is a set of N colors that can be set individually. There are no other colors in a discrete color table other than the colors that you provide. Discrete color tables are usually used by plots like the Boundary, Contour, FilledBoundary, or Subset plots, which need only a small set of colors. Typically, these plots use a color from a discrete color table to color some object and then they use the next color to color another object, and so on. When they reach the end of the color table and still need more colors, they start again at the beginning with the first color from the discrete color table.