Does Gainmaps upload my photos?

No. All processing runs locally in a browser service worker. No file leaves your device. No upload, no server.

How do I batch-encode gain map images from the terminal?

Install the gainmap CLI: npm install -g gainmap, or brew install kirkstrobeck/tap/gainmap, or curl -fsSL https://gainmaps.com/install.sh | sh.

Brighter than white

Gainmaps

Q: What is a gain map image?

A gain map image encodes an SDR photo plus a secondary brightness map. On HDR displays (Apple XDR, Android Ultra HDR, Windows Advanced Color) highlights render above SDR reference white. On SDR displays the image renders normally — the format is fully backward compatible.

The original, gain map encoded. Standard reads the SDR base. Ultra lifts the highlights.

Convert an image

a snowboarder is standing on the top of a mountain, Ultra

a snowboarder is standing on the top of a mountain, Standard

Photo by laura adai on Unsplash · Original

Type

Ultra

Same text, same display — left is SDR white, right is Ultra.

Convert your image

Drop any photo or logo. We add a gain map layer and return it to you instantly — same file format, no upload, no account, no registration. Completely private, runs in your browser.

INSTANT IN BROWSER

Drop an image

JPEG · PNG · WebP · AVIF · HEIC · SVG

Choose files

Make your logo or photos look spectacular on HDR displays. Be the hero at your company.

35 brand logos

Browse all 35 logos →

100 photographs

Browse all 100 photos →

a person standing on top of a sandy hill, Ultra — a person standing on top of a sandy hill

a person standing on top of a sandy hill, Standard — a person standing on top of a sandy hill

brown sand under blue sky during daytime, Ultra — brown sand under blue sky during daytime

brown sand under blue sky during daytime, Standard — brown sand under blue sky during daytime

What is a gain map image?

HDR is an expanded brightness range: image highlights can sit above the SDR ceiling. A gain map image encodes a normal SDR image plus a secondary brightness map. Unsupported apps render the SDR layer and ignore the rest.

EDR is Apple's term for displaying brightness above SDR reference white. HDR describes the image content. They are not the same word and are often misused interchangeably.

The cross-platform technical name is HDR gain map image. Consumer brands include Adaptive HDR (Apple) and Ultra HDR (Android/Google). This site encodes those files locally in the browser. No upload, no server.

Blacks do not necessarily get blacker. EDR lifts highlights, not the shadow floor.

Learn more in /docs →

For developers

Build gain map encoding into your pipeline or CI. MIT licensed, 100% test coverage, available via Docker, npm, Homebrew, and curl.

DockernpmHomebrewcurlCLIMIT licensed100% test coverage

From the terminal

Learn more →

Batch-encode gain map images without a browser.

npx gainmap ./photos

Add Ultra text to your project

Learn more →

npx skills add kirkstrobeck/gainmaps

The skill is the recommended path because this rendering stack has edge-treatment details that can be updated without retyping the implementation by hand. View skill source on GitHub →

Upvote on Product Hunt

Upvotes help designers and photographers find it.

View on Product Hunt →