In the virtual realm, individuals with photosensitive epilepsy (PSE) encounter challenges when using devices, resulting in exposure to unpredictable seizure-causing visual stimuli. The current norm for preventing epileptic flashes in media is to detect asynchronously when a flash will occur in a video, then notifying the user. However, there is a lack of a real-time and computationally efficient solution for dealing with this issue. To address this issue and enhance accessibility for photosensitive viewers, FlashGuard, a novel approach, was devised to assess the rate of change of colors in frames across the user's screen and appropriately mitigate stimuli, based on perceptually aligned color space analysis in the CIELAB color space. The detection system is built on analyzing differences in color, and the mitigation system works by reducing luminance and smoothing color transitions. This study provides novel insight into how intrinsic color properties contribute to perceptual differences in flashing for PSE individuals, calling for the adoption of broadened WCAG guidelines to better account for risk. These insights and implementations pave the way for stronger protections for individuals with PSE from dangerous triggers in digital media, both in policy and in software.