Why Charts Fail Color Blind Readers
Many default chart palettes pair red with green, or use colors of similar brightness, making series hard to tell apart.
Rules for Readable Charts
Never rely on color alone.
Label Directly
Put series names next to lines or bars instead of in a distant legend.
Vary Brightness
Choose colors that differ in lightness, not just hue.
Add Patterns and Shapes
Use dashed lines, markers or hatching as a second cue.
Check Before You Publish
Preview your chart through a color blindness simulator to spot series that merge.