Brighten or darken an image

Small moves first

Brightness shifts the whole image up or down, contrast stretches the distance between dark and light, and saturation controls how strong the colors are. Most photos that look wrong need a little contrast rather than a lot of brightness. Try contrast first and see whether the exposure still looks off.

Use shadows for an underexposed photo

The shadows slider is gamma, and it does something brightness cannot: it lifts the dark and middle tones while leaving the bright ones close to where they are. A face photographed against a bright window is the classic case. Raising brightness lifts the face and blows out the window with it; raising shadows lifts the face and leaves the window alone.

Clipping is permanent

Areas already at pure white or pure black hold no detail to recover. Brightening a crushed shadow lifts it to gray rather than revealing what was there. This is worth knowing before you spend long on a photo that cannot be saved.

How to tell whether a photo is worth working on

Raise the shadows a long way and look at the area you were hoping to rescue. If detail appears, it was there and merely dark, and you can back off to a sensible setting and keep it. If the area lifts as a flat grey patch, or breaks into coloured speckle, there is nothing recorded and no combination of settings will produce any. Noise is what a sensor writes when it has nothing to report, and amplifying it is all that brightening can do.

This is a thirty second test and it saves a great deal of time. JPEGs from phones are the most common disappointment, because the file has already discarded most of what was in the shadows before you ever opened it.

What each control does to the histogram

• Brightness shifts every value up or down by the same amount. Push it far and blacks become grey, which reads as flat and hazy rather than bright.
• Contrast pivots values around the midpoint, pushing lights up and darks down. This is what most photographs described as "dull" actually need.
• Shadows is gamma, and it is the useful one. It bends the curve rather than shifting or pivoting it, lifting dark and middle tones while leaving the brightest largely alone. A face against a bright window is the classic case: brightness lifts the face and blows the window out with it, shadows lifts the face and leaves the window where it was.
• Saturation scales colour intensity. Lifting exposure almost always leaves colour looking thin, so a small bump afterwards is normal. A large one is instantly obvious.

Save format matters here

If the source was a JPEG and you save as JPEG, the adjustment costs a second lossy encode, and the artefacts land hardest in exactly the shadow areas you just lifted. Save as PNG when the picture is going to be edited further, and go to JPEG once at the end. If you are making several attempts to find a look, work from the original each time rather than adjusting your own output, which compounds both the compression and the correction.

Common questions

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