Fix a blue or green cast without ruining the water

Decide what should stay blue or green

The harbour-seal photograph is almost entirely green before restoration: water, seagrass, sand and the seal’s coat sit in a narrow band of colour. Removing green from the whole frame would not solve that problem. It would push the sand and grey-brown coat towards magenta while draining the living green from the habitat.

Start by finding differences the cast has hidden. Black neoprene should remain black. A grey cylinder should not be blue. Pale sand should not be pink, but it need not be paper white. Brown reef growth and green vegetation should not collapse into one hue. Open water, meanwhile, should still look like water.

This is a visual judgement, not a search for a perfectly neutral pixel.

Read a blue frame from front to back

Clear offshore water often produces a blue-dominant photograph because water preferentially absorbs longer wavelengths.[1][2] In the wide reef example, the pale sand channel, nearby reef, striped fish and distant water do not begin with equal colour or contrast. Warming the frame until the far reef looks colourful would contaminate the sand and can turn pale fish markings yellow or pink.

Blue also carries useful depth. A cooler, softer background helps a nearby subject sit forward in the composition. If an edit makes foreground and horizon equally warm, the scene loses both atmosphere and a believable sense of range.

Judge the correction on recognisable materials first. Then decide whether the remaining blue water supports the photograph or dominates it.

Read a green frame by material

Green water may come from suspended matter, plankton, dissolved material and the spectrum of the available light. It is not a reliable depth gauge, and it is not automatically an error. Attenuation also varies with water conditions, not only distance.[3] Temperate kelp, seagrass and algae contain green and yellow-green colour that should survive the edit.

In the seal frame, look separately at the coat, muzzle, sand openings and grass. A useful result gives those materials distinct colour and tone while leaving the water visibly turbid. If a tint correction cleans the water but makes the grass grey and the muzzle pink, it has corrected the display colour rather than the photograph.

Restore first, then shape the water

Five Meters derives a full cross-channel transform from its underwater model. Unlike temperature and tint, which act as broad channel gains, the transform can combine the recorded red, green and blue signals when producing every output channel—so materials that sat in a narrow cast can separate again without forcing every surface toward the same warm tone.

After that restoration, the Water controls use a model-derived feathered matte to concentrate hue, saturation and luminance changes on likely water while subjects stay protected. Check boundaries around fins, vegetation and blue equipment as you refine; small Water adjustments usually finish a believable blue or green frame.

Stop before the cast becomes its opposite

Reduce the edit if sand or bubbles turn pink, black gear becomes brown, kelp loses its green variation or open water becomes neutral grey. Also inspect shadows for coloured noise: a strong correction can expose how little clean warm-channel information the camera recorded.

The aim is not to prove the original colour of every surface. It is to recover useful separation from the captured channels while retaining the water, visibility and light of the dive.