> "First, choose colors that can be easily distinguished. If possible, keep them far apart on the spectrum. If not, differentiate them some other way, such as by intensity or saturation."
Because "keep them far apart" on the spectrum might not be helpful when taken litereally, here is a link to Lines of Confusion Diagrams im CIE 1932 color space.
> "Second, use other cues if possible. Color is complex, so if you can add another component to a line on a graph, such as a dashed versus dotted pattern, or even good labeling, that helps a lot."
I find this easier said than done. My issue with alternative cues is that they often introduce a form of unintentional order or hierarchy. For example: When I want to plot two different variables and I want to avoid that one of them appears more important than the other I can do this nicely with color.
Other line attributes are not so easy. A solid line will always seem more important than a dashed or grey line and a dashed line more important than dotted one. Trying to change the dash and dot pattern so that they have similar grey values makes them hard to distinguish. I find color is the easiest way to distinguish things without introducing unintentional order.
Because "keep them far apart" on the spectrum might not be helpful when taken litereally, here is a link to Lines of Confusion Diagrams im CIE 1932 color space.
https://www.color-blindness.com/2007/01/23/confusion-lines-o...
> "Second, use other cues if possible. Color is complex, so if you can add another component to a line on a graph, such as a dashed versus dotted pattern, or even good labeling, that helps a lot."
I find this easier said than done. My issue with alternative cues is that they often introduce a form of unintentional order or hierarchy. For example: When I want to plot two different variables and I want to avoid that one of them appears more important than the other I can do this nicely with color.
Other line attributes are not so easy. A solid line will always seem more important than a dashed or grey line and a dashed line more important than dotted one. Trying to change the dash and dot pattern so that they have similar grey values makes them hard to distinguish. I find color is the easiest way to distinguish things without introducing unintentional order.