Economist and Apache ECharts Case Study¶
Status: draft Scope: full-length Leonardo-style and OKLCH comparison of two unexpectedly strong reference palettes Source: Reference Categorical Palette Corpus
This note compares the full published palette lengths for The Economist and
Apache ECharts. Both performed unusually well in the first-five accessibility
pass, even though stylistically they are not direct templates for DFT.
The chart pairs two lenses:
- full-length Leonardo-style weighted fail-rate curves
- all-slot OKLCH hue/chroma placement for the authored colors
Delta E is a perceptual color-distance score. Lower values mean colors become harder to distinguish; higher values mean clearer separation.
The Economist¶
- full length: 10 colors
- weighted fail rate at step 5: 0.5%
- weighted fail rate at full length: 7.2%
- weakest full-set Delta E: 0.3
- weakest full-set pair:
c4-c10 (achromatopsia)
Apache ECharts¶
- full length: 11 colors
- weighted fail rate at step 5: 0.6%
- weighted fail rate at full length: 6.5%
- weakest full-set Delta E: 0.4
- weakest full-set pair:
c3-c6 (achromatopsia)
