Flashing Content

Visual content that alternates between contrasting states at a rate that can trigger seizures in people with photosensitive epilepsy. WCAG defines a flash as a pair of opposing luminance changes or a transition involving saturated red. Content with more than three flashes per second that exceed luminance or red flash thresholds may be hazardous. Flashing includes both intentional effects (strobe lights, animations) and incidental flashes (lightning, camera flashes, rapid scene cuts). WCAG Success Criterion 2.3.1 requires that content not contain anything that flashes more than three times per second, or that flashes fall below the general flash and red flash thresholds.