Introduction

Accessible data visualizations extend beyond aesthetics to meet established standards and accommodate diverse visual abilities. This presentation demonstrates how to create visualizations that comply with Web Content Accessibility Guidelines (WCAG) contrast requirements, support users with color vision deficiencies, and convey information through multiple encoding channels. The topics in the presentation explore practical techniques using colors, patterns, SVG accessibility features, and alternative data formats.

This presentation is designed for data scientists, visualization specialists, dashboard designers, and accessibility auditors who need to communicate findings effectively to diverse audiences. Attendees will benefit by:

• Learning practical techniques to make visualizations accessible without sacrificing analytical depth
• Gaining implementation strategies for common data visualization libraries
• Acquiring skills to expand their reach to users with visual impairments
• Taking away ready-to-use color palettes and pattern sets for immediate implementation

Topics

Color Accessibility

Data visualizations must meet WCAG contrast ratios (≥3:1) for distinguishable elements. Our optimized palette features:

• Eight distinct colors plus neutral gray for invalid data
• CIEDE2000 perceptual differences >20 between colors
• Verified compatibility with various color vision deficiencies
• Print-friendly CMYK values (ISO Coated V2 300% or Pantone C)
• Contrast ratios >3.0 (WCAG AA-level) against white and black backgrounds

Pattern Implementation

Patterns provide critical secondary encoding when color alone is insufficient, we'll present:

• Unique pattern paired with each color
• Area fills that maintain distinction at various scales
• Sequential pattern densities for quantitative data
• Pattern elements adaptable as point markers
• Implementation via SVG <pattern> tags

Technical Implementation

Practical examples will demonstrate:

• Using color contrast checkers for validation
• Implementing SVG <pattern> elements
• Creating accessible SVG with proper ARIA attributes
• Providing alternative data formats (e.g. HTML tables with semantic descriptions)
• Testing with screen readers and accessibility tools

Conclusion

Implementing these practices creates data visualizations that are not only compliant with accessibility regulations but also more effective for all users. The cusy Design System offers open-source resources to implement these techniques across various visualization libraries.