How the image brightener works
Each pixel in a photo has red, green and blue values from 0 (dark) to 255 (bright). Moving the slider adds the same amount to all three values for every pixel, or subtracts it when you go negative. That lifts or lowers the whole image evenly, which makes it predictable and fast.
Because the change is even, it also lifts the shadows and the highlights equally. Pixels that hit 255 stop there, so pushing too far turns light areas such as skies, white shirts and faces into flat white with no detail. Most photos only need a modest boost.
| Photo | Try | Watch out for |
|---|---|---|
| Slightly dark | +10 to +25 | Nothing, usually safe |
| Very dark indoor shot | +30 to +50 | Skin and lamps turning white |
| Scanned paper | +20 to +40 | Faint text fading away |
| Overexposed | −10 to −30 | Shadows getting muddy |
Brightness vs exposure vs contrast
These three settings sound alike but do different jobs:
In practice, for a photo that's simply a bit too dark, brightness does the job. Reach for exposure in a full editor when a photo is badly underexposed and you need to protect the highlights.
- Brightness (this tool) shifts every pixel up or down by the same amount.
- Exposure, in camera apps and Lightroom, scales light the way a longer or shorter exposure would, so bright areas change more than dark ones.
- Contrast stretches the gap between darks and lights. After brightening, photos can look a little flat; adding contrast with the Image Contrast tool brings back depth.
Tips for brightening dark photos
Brighten first, then add a touch of contrast; doing it the other way round tends to crush the shadows you're trying to rescue. Very dark phone photos also carry noise, grainy speckles that become more visible when brightened. If that happens, run the result through Image Denoise. And if a photo is beyond rescue, retaking it near a window will always beat any slider.
Edit a copy, not your only original. Each brightened download is saved as a new JPG, so the original stays on your device unchanged and you can always start again from it.
