It depends on your GPU. On a typical laptop with hardware video decoding, 4K 60 fps footage is processed faster than real time, usually 40–60 frames per second.

Free · No upload · 4K60

Give your dive videos their colors back.

Q: What does it cost?

Nothing. The tool is free with no limits. Corrected videos get a small watermark in the corner – free to remove. If it saves you time, you can support development with a voluntary donation.

Underwater color correction that removes the blue and green cast automatically – and runs right in your browser on your own graphics card. Your video never leaves your computer.

Start the app → How it works Donate Chrome or Edge on Windows, Mac and Android · Safari on iPhone (iOS 17+, beta). No account, no install.

Giant moray eel swimming across a Red Sea reef with a heavy blue cast, before color correction — Red Sea · giant moray · GoPro 2.7K · drag to compare

The same giant moray after automatic color correction: natural skin pattern, white sand and golden corals — Red Sea · giant moray · GoPro 2.7K · drag to compare

01/ How it works

Three steps. No settings, unless you want them.

The tool measures how much red the water has absorbed, detects the type of scene and corrects every frame with temporal smoothing so colors never flicker.

Pick your videos

Drop one file or a whole dive day. MP4/MOV in H.264 or HEVC, including 10-bit from GoPro, DJI and phones.

Check before and after

Auto picks a preset for blue water, reef, close-ups or green water. Adjust strength and compare live – or leave it on Auto.

Press start

Choose a folder and the corrected MP4 is written straight to your disk while it processes. Audio comes along.

02/ Examples

Drag the line. Every scene type.

Real GoPro frames from the Red Sea, corrected with the preset Auto picked for each scene. Nothing retouched by hand.

Hawksbill turtle on the reef, before — **Hawksbill turtle on the reef**Blue water preset

Hawksbill turtle on the reef, after — **Hawksbill turtle on the reef**Blue water preset

Eagle ray in open blue water, before — **Eagle ray in the big blue**Deep blue preset

Eagle ray in open blue water, after — **Eagle ray in the big blue**Deep blue preset

Coral reef and sand, before — **Reef and sand at 15 m**Blue water preset

Coral reef and sand, after — **Reef and sand at 15 m**Blue water preset

Camouflaged octopus next to staghorn coral, before — **Octopus hiding by the staghorn coral**Reef preset

Camouflaged octopus next to staghorn coral, after — **Octopus hiding by the staghorn coral**Reef preset

Camouflaged stonefish lying on a wreck plank, before — **Stonefish on the wreck**Reef preset

Camouflaged stonefish lying on a wreck plank, after — **Stonefish on the wreck**Reef preset

Night dive: a Phyllidia nudibranch on the coral, before — **Night dive · *Phyllidia* nudibranch**Close-up preset

Night dive: a Phyllidia nudibranch on the coral, after — **Night dive · *Phyllidia* nudibranch**Close-up preset

03/ No upload

Your video stays on your computer.

A website does not have to be a server doing work for you. This page is downloaded once and then runs as a program in your browser. The video is read from your disk, decoded and encoded by your graphics card's video engine, corrected by the GPU and written back to your disk. Turn off Wi‑Fi after the page has loaded – it still works.

That is also why it is fast: the frame never leaves the graphics card. No queue, no file size limit, no account. The only thing measured is an anonymous, cookieless page-view count – never your files.

● your disk → browser (reads the file)

● GPU video engine decodes HEVC/H.264

● GPU shader corrects the colors

● GPU video engine encodes H.264

● browser → your disk (writes the file)

● upload to a server

● cloud processing

● account, cookies, ad tracking

04/ Features

Built for real dive footage.

Resolution4K · 60 fps · 10-bitHardware decoding of HEVC and H.264 via WebCodecs. Up to 5.3K with HEVC output.

SpeedFaster than real timeTypically 40–60 fps for 4K60 on a laptop with hardware video decoding.

Scene presetsBlue water · reef · close-up · greenAuto-detected per clip, tuned on real Red Sea footage. Override any time.

CorrectionAutomatic red compensationGray-world white balance and percentile contrast, measured per frame and smoothed over time.

BatchMany files at onceQueue a whole dive day, pick one folder and let it run.

OutputMP4 with audioH.264 up to 4K at high bitrate (5.3K kept as HEVC on request). The audio track is copied unchanged – no re-encoding.

05/ Questions

Frequently asked questions.

Does the tool upload my video?

No. The page is downloaded once and then all processing runs as a program inside your browser. The video is read from your disk and written back to your disk. Nothing is sent to Nordrift or anyone else.

Which browsers work?

Google Chrome and Microsoft Edge on Windows, macOS, Linux, ChromeOS and Android, plus Safari on iPhone and iPad with iOS 17 or newer (beta: finished videos are saved via the share sheet). Firefox does not support WebCodecs yet.

How fast is it?

It depends on your GPU. On a typical laptop with hardware video decoding, 4K 60 fps is processed faster than real time, usually 40–60 frames per second. Without hardware decoding the browser falls back to software and gets slower, but it still works.

Which files are supported?

MP4 and MOV with H.264 or HEVC (H.265), including 10-bit footage from GoPro, DJI, Insta360 and phones. Output is MP4 with H.264 at up to 4K at high bitrate (5.3K sources are scaled to 4K by default, or kept at 5.3K as HEVC), and the audio is copied unchanged. GoPro telemetry tracks (GPS/gyro) are not carried over.

How does the correction work?

Water absorbs red light first. The tool measures how much red (and optionally blue) is missing relative to green, compensates per pixel, sets white balance with a gray-world estimate and stretches contrast between low and high percentiles. The parameters are measured continuously and smoothed with a median over several frames so colors do not flicker. Scene presets adjust the strength of red compensation, the percentile range and the smoothing window: blue water keeps the water blue instead of cyan, close-ups preserve highlights from torches and strobes.

Does it work offline – on a liveaboard?

Yes. Open the app once with internet; your browser keeps a copy, and www.nordrift.dk/color-correction/app then opens without a connection – the correction itself never needed the internet. In Chrome and Edge you can also install it as an app (menu ⋮ → “Install app”) to get an icon on the desktop. Don’t use “Save page as”: a saved HTML file loses folder access and storage. Reviews and the usage counters need a connection; iPhone HEIC photos need the HEIC decoder to have been loaded once online.

What does it cost?

Nothing, and there are no limits. Corrected videos get a small watermark in the corner – free to remove. If it saves you time, you can support development with a voluntary donation.

06/ Reviews

Rated in sea turtles.

Voluntary donation

Free for everyone. Supported by those who can.

The tool is built and maintained by one person in his spare time. A donation goes to development, testing on more cameras and browsers – and a coffee after the dive.

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