Make any image glow brighter than white.

Drop the image into the tool at the top of this page, set how strong the glow should be and download the file. Post it as it is, without editing or re-saving it in another app first. It is an Ultra HDR JPEG, and on an HDR phone its bright parts render above the white of the app around them, which is what makes it look brighter than every other post in the feed.

No. The glow needs a display that can go above white, which means a recent iPhone, Pixel or Galaxy, or an HDR laptop or monitor. On everything else the same file still shows correctly, only without the extra brightness.

Because the screen you are reading this on cannot go above white. To show the effect at all, the simulation dims both halves by the same amount and lets only the glow keep its level. The ratio between the two is what your eye reads on real HDR hardware, and that ratio is honest.

No, and there is no server that could receive it. Decoding, the gain map and the packaging all run in this tab. That is also why the first conversion pauses to fetch the image engine — about 3 MB over the wire — and why every conversion after it is immediate.

A second, small greyscale image stored inside the JPEG. It tells a capable display how much brighter each pixel may be rendered than the ordinary image next to it. The container is ISO 21496-1, the same format Adobe and Google write.

One JPEG. It contains the standard image, the gain map and the metadata that links them, so nothing about uploading it is special. Old software simply ignores the extra part. Below the download button you can also take the gain map on its own, as a greyscale PNG — the layer itself, useful for checking where the threshold landed or for working with it in Photoshop, which reads gain maps. We used to offer PNG and WebP copies of the picture there and removed them: neither format can carry a gain map, so under a gain map tool they were a dead end with a label on it.

Because we cannot show you that it would carry the glow. AVIF can hold HDR, but through a different mechanism than a gain map, and the pixels a browser canvas hands out are eight-bit SDR. Asked for AVIF, Chrome silently returns a PNG instead — we measured it. An AVIF from here would be an ordinary SDR picture wearing a format that promises more, and offering that is exactly what we said we would not do.

Something in the chain re-encoded the file. Screenshots, several messengers and most scheduling tools rewrite the image and discard the gain map. Post the downloaded file directly and it survives.

It is not a trick. The gain map is ISO 21496-1, an industry standard backed by Google, Apple, Adobe and Samsung, and every recent iPhone, Pixel and Galaxy already writes one into every HDR photo it takes. Platforms have to read that metadata, or their own users' ordinary holiday photos would look washed out. What could change is a cap on how far the tone mapping is allowed to go, say around +2 EV, to tone down the most extreme cases. The file would still glow, just less aggressively.

The file itself is not a red flag: it is the same standard format a recent phone camera writes on its own, so an upload from here is not technically distinguishable from an ordinary HDR photo. It does not bypass anything and breaks no technical rule. What we cannot promise is how a platform's moderation judges an image that overwhelms the rest of a feed — some platforms treat aggressively attention-grabbing content as spam or harassment, and that is a judgment call on their end, not a technical one. We have had no reports of this happening and have not measured it either way, so we cannot rule it out. The safer choice, and usually the better-looking one, is restraint: let the highlights glow rather than blowing out the whole frame.

Yes, both are the main case. JPEG has no alpha channel, so transparency is flattened onto black before the gain map is computed, which is usually what you want for a mark that is supposed to glow.

Nothing, and there is no account. The conversion runs on your device, so it costs us nothing to give away.