Keeping cartoons safe: why we check for flashing

Cartoons need a flashing check because fast flashes and certain flickering patterns can trigger seizures in people with photosensitive epilepsy. Every Duma Meow clip I make goes through a flashing-safety check and has to come out at zero flashes per second before it's published.

Here's why that matters, what counts as a risky flash, and how to keep animation safe without losing energy.

Why flashing can be dangerous

Photosensitive epilepsy is a form of epilepsy in which seizures can be triggered by flashing lights or certain visual patterns. Not everyone with epilepsy is photosensitive, and some people don't know they are until it happens. That's what makes it a public safety issue rather than a niche concern: you can't know who's watching.

Triggers can include:

• Rapid flashes between light and dark.
• Fast flicker, especially at certain frequencies.
• Strong red flashes.
• High-contrast patterns like stripes or checks that move or flicker.

If you or someone you know has seizures or concerns about light sensitivity, a doctor is the right person to talk to. This post is about making content safer, not medical advice.

A famous example

The most famous case in animation happened in Japan in December 1997. An episode of the Pokémon TV series included a sequence of rapid red and blue flashes, and a large number of viewers, many of them children, were taken to hospitals with symptoms including seizures. The incident led broadcasters to adopt stricter guidelines for flashing in TV animation.

What the guidelines say

Several organizations publish flashing guidelines. The widely used web accessibility standard, WCAG, includes a rule called "Three Flashes or Below Threshold": content shouldn't flash more than three times in any one-second period, unless the flashes are below set brightness and size limits. Broadcasters in some countries have similar rules and use automated tools to test footage.

These rules give a useful baseline. For Duma Meow, I aim stricter: zero flashes per second.

Why zero?

Short-form videos are watched on phones, often in dark rooms, at close range and on autoplay. Viewers don't choose each clip; the next one just starts. That's exactly the situation where a surprise flash could reach someone who's vulnerable.

A zero-flash rule is also simpler to work with. There's no debate about whether a scene is "just under" the threshold. If it flashes, it gets changed.

How the check works

Every clip, a vertical 1080×1920 Short, goes through a flashing-safety check. A flash, in the sense these guidelines use, is a sudden large change in brightness, especially across a big area of the frame. The pass mark for Duma Meow is zero flashes per second; a clip that doesn't hit it doesn't go out.

Checking the finished video, rather than individual pieces, is what catches everything: animation, backgrounds, transitions and effects together.

Formats that need extra care

Some Duma Meow skit formats sound like they could invite flashing, like the flash-dodge dance, the expanding brain meme or a burst of zoomies. They're held to the same zero-flash rule. The general trick for formats like these is getting the energy from motion and timing instead of light.

How to keep animation exciting without flashing

• Use motion, not light. Speed lines, squash and stretch, and fast poses feel energetic without flashing.
• Fade, don't strobe. If brightness has to change, ramp it over several frames.
• Keep big color changes small. A small glow in a corner is far safer than a full-screen flash.
• Avoid red flashes entirely.
• Watch out for patterns. Rapidly moving stripes or checkerboards can be a problem too.
• Test the final export, not just individual pieces.

Free tools and habits

Some free and commercial tools analyze video for flashing risk. Even without one, you can scrub through your edit frame by frame looking for sudden full-frame brightness jumps. Make checking part of your export routine, not something you remember occasionally.

Safety is part of the craft

Comedy should leave people laughing, not hurt. A flashing check takes a few minutes per clip, and it means anyone can watch without worrying. If you want to see how the rest of a Short comes together, read how a 15-second cartoon Short gets made or animating a dance trend with cats.

If you make animation, add a flashing check to your export checklist today and replace any strobe effect with motion before you publish.