Color-only Information

Color-only information refers to content where color is the sole visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. WCAG Success Criterion 1.4.1 (Level A) requires that color is not used as the only visual means of conveying information. A secondary visual cue -- such as text, icons, patterns, or shape -- must always accompany color.

Common examples include: links that are only distinguished from surrounding text by color (no underline), required form fields marked only with a red label, status indicators that use green for success and red for error without any text or icon, chart legends that rely solely on color to distinguish data series, and error states indicated only by changing a border from gray to red.

This issue is fundamentally about redundancy. Color can and should be used to reinforce information, but it must not be the only channel. Users who cannot perceive color differences -- due to color blindness, monochrome displays, high contrast mode, or simply printing the page in grayscale -- must still be able to access the same information.

Approximately 300 million people worldwide have color vision deficiency (color blindness). The most common form, red-green color blindness, affects about 8% of men. For these users, a red error border on a form field looks identical to a green success border. Required fields marked only in red are indistinguishable from optional fields. Status badges that use only green/yellow/red are meaningless.

Users with low vision who use high contrast modes or custom color schemes also lose color-based information. Windows High Contrast mode, for example, overrides page colors entirely, stripping away any color-only visual cues.

Even users with typical color vision can be affected in certain contexts: projected presentations wash out colors, poor display calibration shifts hues, and ambient lighting can make similar colors indistinguishable. Using redundant visual indicators ensures the information reaches everyone regardless of conditions.

Scrutia identifies elements where color is the sole differentiating visual cue. It detects links without underlines or other non-color distinction, form fields marked as required only by label color, status indicators using only color, and chart elements without patterns or labels. Each finding includes the element location and a recommendation for adding a redundant non-color indicator.