Project Themes: Visual Accessibility, Geovisualization, Simultaneous Contrast, Inclusive Design, Open-Source Tools
Research Team
PI: P. William Limpisathian, Susannah Cox
The Modular Accessible Perceptibility (MAP) Toolkit is a new open-source solution for detecting perceptual accessibility issues in mobile map interfaces—especially those caused by simultaneous contrast. Unlike legacy standards that rely on simple brightness contrast, MAP incorporates advanced perceptual color science to reveal when designs may look legible but actually mislead users due to human visual system dynamics. The toolkit includes a perceptual engine, diagnostic tool, and an Android-based mobile app (built outside the Google ecosystem) to support inclusive geovisualization and mobile UI design.
Objective
This project aims to develop and validate the MAP Simultaneous Contrast Detection Toolkit, a perceptually grounded software tool for evaluating visual legibility in mobile map interfaces. The MAP Toolkit will help designers identify and address perceptual contrast risks—especially those caused by simultaneous contrast—that are not detected by current accessibility checkers. Our goal is to empower developers with a deeper, data-driven understanding of visual accessibility, contributing to a more inclusive mobile design ecosystem.
Background
Current accessibility tools, such as those built around WCAG 2.0 and 3.0 standards, evaluate color contrast based primarily on lightness (luminance) ratios. While helpful for text readability, these metrics fall short when applied to complex graphics like maps or multicolored interfaces, where simultaneous contrast can cause perceptual shifts in color appearance based on surrounding hues.
Simultaneous contrast is a visual phenomenon in which a color’s perceived chroma, hue, or lightness shifts due to its proximity to other colors. This can significantly alter how users interpret map symbols, layers, or navigation elements—especially in mobile environments where screen size, lighting conditions, and attention demands are high.
The MAP Toolkit combines advanced perceptual modeling with open-source software to address this issue head-on.
Proposed Research Questions
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How can perceptual models of human color vision (CAM16-UCS and CAM16 CCz) be translated into practical tools for UI and map interface evaluation?
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What new insights can simultaneous contrast detection provide that are missed by WCAG contrast ratios?
Hypothesis
We hypothesize that standard WCAG contrast tools overlook critical perceptual effects—particularly simultaneous chromatic shifts—that can undermine legibility in map interfaces. By incorporating these effects into our perceptual model and building them into a usable tool and Android-based app, we will enable designers to detect issues early and improve accessibility outcomes for diverse user groups, including those with color vision deficiencies or neurodiverse perceptual profiles.
Innovation and Implementation
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MAP Engine: A Python-based perceptual analysis backend using CAM16-UCS and CCz modeling to assess chroma-based perceptual risk.
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DSimu Score: A novel metric that flags color pairings prone to simultaneous contrast distortions.
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MAP Contrast Index: An aggregated perceptual legibility score for entire interfaces.
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Android App (Outside Google Ecosystem): A FOSS mobile app installable via platforms like F-Droid that enables designers to upload UI images or capture live screenshots and receive real-time MAP diagnostics.
Possible Implications
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Design Accessibility: Provides designers with perceptually informed tools to build more legible and inclusive maps and interfaces.
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Tool Innovation: Offers a robust alternative to WCAG-based standards, particularly for non-textual, complex visual information like geospatial content.
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Open Access: By releasing this as an open-source toolkit and app, we support community contributions and future extensibility across digital platforms.
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Inclusivity by Design: Encourages accessibility thinking from the earliest design phases, particularly for mobile platforms where space and color carry more cognitive load.
In summary, the MAP Toolkit project moves beyond legacy accessibility checks to offer a forward-looking, scientifically grounded, and open-source approach to visual accessibility in maps and interfaces. By surfacing perceptual contrast issues before they become usability problems, the toolkit helps designers see accessibility more clearly—and build more inclusive tools for all.