Brighten an image, dark photos made light.

To brighten an image is to make its tones lighter without losing the dark parts altogether or turning the light parts to flat white. This tool does it with five sliders, exposure, brightness, shadows, highlights and contrast, and an Auto button that picks the numbers from the picture itself. The same page also works as a way to whiten an image: the Whiten paper start makes a grey, yellow-looking scan or document photo bright and clean. It works on one picture or many at once, saves JPG, PNG or WebP, and never uploads anything.

How to brighten a photo

1. Drop one or more pictures on the box, click it to choose them, or paste one with Command V or Ctrl V. HEIC photos from an iPhone work too.
2. Press Auto. It reads the brightness of the picture on screen and sets the sliders. A line under the buttons says what it chose.
3. Fine tune with Exposure, Brightness, Shadows, Highlights and Contrast. Or start from Dark photo, Backlit, Washed out or Whiten paper.
4. Press and drag anywhere on the picture to move the line between the original and the result. Hold the B key to see the original at once.
5. Choose Format and Quality, then press Download the picture, or Download all as ZIP if you added more than one.

What each slider does

Exposure works the way a camera does. One stop (+1 EV) doubles the light that the picture holds, so it is the right slider for a photo that was simply taken too dark. The tool converts the picture to linear light, multiplies it and converts it back, which keeps colours natural. Brightness lifts the middle tones most and leaves pure black and pure white where they are, so it cannot burn out the lightest parts. Shadows lifts only the dark pixels, Highlights pulls down only the light ones, and Contrast bends the tones into an S so dark gets darker and light gets lighter. A negative contrast flattens them.

Here is what a few settings do to plain grey pixels, on a scale where 0 is black and 255 is white. These are the real values the tool uses.

Read across the Shadows row: a dark 60 rises by 26, a grey 100 by 15 and a light 180 by only 2. That is the point of the slider. Exposure +1 EV is different: it sends the light 180 up to 245, and every grey from about 188 up turns pure white.

Brighten a dark photo, a backlit one or a scan

A photo that is dark all over needs light everywhere, so use Exposure first. About +0.7 EV and some Shadows is the Dark photo start. A backlit portrait has a bright window behind a dark face. Exposure would burn out the window, so use Shadows to bring up the face and a negative Highlights to hold the sky: that is the Backlit start. A washed out photo has plenty of light but no punch, and it needs Contrast more than brightness.

For a scan or a photo of a page, Whiten paper raises exposure, brightness and contrast together. The grey paper moves up towards white while the ink stays dark. Watch the note under the graph: when more than a few percent of the picture reads as pure white, detail is lost there, and you should back off a little.

Colour, orientation and file quality

Photos from an iPhone or a camera carry a note about which way up they were taken. The tool turns the pixels the right way and saves them upright, so nothing ends up sideways. If a JPG or PNG has its own colour profile, such as Display P3, the tool works in that profile's own numbers and saves the same profile back. It does not copy camera details like the date or the place, so the saved picture holds no location. A picture with see-through parts keeps them in PNG and WebP; a JPG has no see-through, so those parts turn white.

JPG is saved with MozJPEG at the Quality you set, 92 by default, and PNG is saved without any loss. The preview on screen uses a smaller copy, up to 1400 pixels on the long side. The file you download is made from your original at its full size.

Common problems

• The light parts turned flat white. Lower Exposure, or pull Highlights down. The graph shows a tall bar at the far right when this happens.
• Brightening made it look grey and noisy. A very dark photo holds little detail. Add some Contrast after you lift it, and use less Exposure and more Shadows.
• A GIF only brightens one frame. GIFs are read as a single picture here. Use a GIF tool for moving pictures.
• The sliders were reset. By design: the next picture is a different picture. Format and Quality are remembered in this browser.

To change more than light, use the full photo editor. To turn the colours around instead, try invert colors, and to make a big photo smaller afterwards, use the image compressor.