How to brighten a dark photo on iPhone

Start here. For most dark photos the Photos app is all you need: it is already on the phone, it costs nothing, and its Adjust settings include controls PhotoTune does not have, Highlights and Shadows among them.

Apple's iPhone guides name Exposure, Brilliance, Highlights and Shadows among the light settings, and do not say what each one does. Apple's guide to Photos on Mac, which uses the same names, does. Exposure adjusts the lightness or darkness of the entire image. Brilliance brightens dark areas, pulls in highlights and adds contrast to reveal hidden detail. Highlights adjusts the highlight detail, and Shadows the detail that appears in shadows. Brightness adjusts the brightness of the photo, and Black Point sets the point at which the darkest parts become completely black, which Apple says can improve the contrast in a washed-out image.

So there are two different jobs here. Exposure is for a photo that is dark all over. Brilliance and Shadows are for a photo whose dark parts are the problem, which is usually the case when a face is darker than the window or sky behind it.

PhotoTune's Light group has three tools for a dark photo. Lighting is Exposure and Contrast for the whole photo, the same kind of control as Exposure in Photos. Auto Adjust measures the face rather than the whole frame and sets those two sliders for it in one tap. Flash, in Effects, is the one that works differently: it adds light where the face is and lets the rest of the frame fall darker.

Flash finds the face on the phone and lights a wide, soft-edged area centred on it. The light it adds rolls off as it nears white instead of clipping, so it does not turn a bright window or sky white, and the background beyond the lit area goes darker rather than brighter. Nothing is generated and no feature moves: it is light on the photo you took.

All three run on the iPhone. The photo is not sent anywhere.

Apple's guides describe one Photos setting aimed at a face: Studio Light, a Portrait Lighting effect that lights the face brightly and gives the photo an overall clean look. It works on photos taken in Portrait mode, and on supported models Photos can turn a photo of a person taken in Photo mode into a portrait first. Open the photo, tap the edit button, tap the button at the top that brings up the Portrait Lighting effects, slide your finger to Studio Light, and set its strength with the slider below the effects.

For any other photo the choice is between lifting the dark tones, which brings a dark background up with the face, and lighting the face itself, which is what PhotoTune's Flash does.

Either way, the aim is the light the person was standing in, not a different skin tone. Brighten until the eyes read clearly, compare with the original, and if the skin has turned grey or chalky, back off.

A face against a bright window often comes out dark: the window is far brighter than the face, and an exposure that keeps the window from turning white leaves the face in shadow. Anything that brightens the whole photo brightens the window with it, and a sky that was almost white goes the rest of the way. Whatever the edit turns pure white has no detail left in the edited photo.

So for a backlit photo, leave Exposure for last. In Photos, start with Brilliance or Shadows, and use Highlights for the sky. In PhotoTune, start with Flash. And if the sky was already pure white in the photo as taken, no edit brings it back: there is nothing there to recover.

A photo taken in the dark carries noise, and brightening it brightens the noise too. That grainy look is the photo's own and the best cure is less brightening: get the face to read clearly, not the room to look like daylight.

A brightened photo also tends to look flat and grey, because its darkest parts are no longer dark. Add a little contrast back, with Contrast in PhotoTune or Contrast or Black Point in Photos, and look at the photo at the size people will see it, not zoomed in on the face.

Photos from one room or one evening usually need the same fix. Apple's guide describes Copy Edits and Paste Edits in Photos for exactly this, onto one photo or a selection, and says Photos adjusts the white balance and exposure of each pasted photo to make them match better.

In PhotoTune the same job is a Preset: save the light from one photo, then apply it to the next with one tap, or to up to 100 photos at once with Apply to photos or Batch. A Preset that carries Flash aims it at the face in each photo, so it lands on whoever is in the frame. Saving a Preset, like saving a photo, needs a subscription.

PhotoTune is an iPhone app; there is no Android or web version. Saving an edited photo needs a subscription, and the annual plan starts with 3 days free. The pricing page has every plan and what the trial turns into.

What this guide says about software other than PhotoTune comes from the pages below, read on the dates shown. The PhotoTune screenshots are captures of the app.