How to use gamma correction
- Choose one or more photos.
- Set Gamma between 0.2 and 5, in steps of 0.05. The default is 1.4.
- Choose Save as and a Quality if you want a lossy format.
- Press Apply, then compare with the original.
What it does and when to use it
Gamma correction bends the tone curve instead of shifting it. It is the right fix for a photo that is dark but not clipped: a room lit by a window, a face in the shade, an evening shot. It is also a quick way to make a scanned document or a screenshot of a dim interface easier to read.
Values below 1 work the other way, giving depth to a hazy or overexposed picture without crushing the shadows to solid black.
For a change that also stretches darks and lights apart, use Image Contrast. For a plain lighten or darken, Image Brightness is simpler. To check how your tones are spread before and after, look at the image histogram.
How it works
Each red, green and blue value v (0–255) passes through a lookup table built from:
output = 255 × (v ÷ 255)^(1 ÷ γ)
When γ is greater than 1, the exponent is below 1, which raises every value between 0 and 255. At v = 0 and v = 255 the result is always 0 and 255, so the end points stay fixed. Transparency is left untouched. The image is processed in a background worker on your device and is not uploaded.
Worked examples
These values come from the tool’s own formula.
| Input value | γ 0.7 | γ 1.4 (default) | γ 2.2 |
|---|---|---|---|
| 30 (deep shadow) | 12 | 55 | 96 |
| 128 (middle grey) | 95 | 156 | 186 |
| 220 (light grey) | 207 | 229 | 238 |
| 0 and 255 | 0 and 255 | 0 and 255 | 0 and 255 |
- A dim indoor photo at the default 1.4. Middle grey rises from 128 to 156 and a deep shadow from 30 to 55. Near-white tones barely move, from 220 to 229, so the window does not blow out.
- A washed-out beach photo at 0.7. Middle grey drops to 95 and light grey to 207, giving richer colour while white stays white.
Limits and tips
- Very high values make a photo look flat and milky, because all tones crowd toward white.
- Gamma treats the three colour channels the same way, so it does not fix a colour cast.
- Keep PNG or a high quality when saving if you plan more edits.
Frequently asked questions
Should I use gamma or brightness for a dark photo?
Which value should I start with?
Is this the same as the 2.2 gamma of screens?
Why does a dark photo look noisy after a big lift?
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