About Brightness
Brightness scales the lightness of every pixel in an image by the percentage you set. A hundred percent leaves the picture as it is, higher values lighten it, and lower values darken it — so the setting reads directly as a multiplier and the value that does nothing is easy to reason about.
The typical reason to reach for it is an exposure that was wrong at capture time, whether from a camera metering against a bright sky or a screenshot taken with a dimmed display. It is also the fastest fix for a scan that came out grey rather than white, though for that problem contrast usually does more work once brightness has lifted the overall level.
Scaling is a blunt instrument compared with a proper exposure adjustment: pushing brightness far above a hundred percent moves light areas towards pure white and flattens the detail there, because pixels that reach the maximum have nowhere left to go. Raising it modestly and checking the highlights is the safer habit.
How to use Brightness
- 1 Choose the image to adjust.
- 2 Enter the brightness percentage — above 100 lightens, below 100 darkens.
- 3 Check the brightest areas, which lose detail first when brightening.
Frequently asked questions
What value leaves the image unchanged?
One hundred percent, because the setting is a direct multiplier on each colour channel. Reading it that way makes the numbers easy to reason about — a value of 120 lifts everything by a fifth.
Why did my highlights turn into flat white?
Because brightening scales the channels upward and any pixel that reaches the maximum is clipped there. Detail in the brightest areas is lost rather than compressed, so use a modest increase and check the highlights before going further.
Is brightness the same as exposure?
Not exactly. Exposure is a multiplicative change in the photographic sense, while this is a straightforward scaling of the pixel values. For routine lightening the two are close enough; for careful correction the dedicated exposure tool models the photographic behaviour more closely.
Free, online, and private
Free to use
Brightness is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Brightness behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Mapping | the field is divided by 100 and handed to the CSS brightness() filter, so 100 asks for a multiplier of 1 and the default 120 asks for 1.2 |
| Amount | 0 to 300, default 120; values outside that span are clamped in the run function before the filter string is built |
| At zero | the filter receives a multiplier of 0, which drives every channel to its floor rather than to some minimum visible level |
| Output format | always PNG at the original width and height |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Brightness does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- A single multiplier is the whole model. There is no separate control for shadows, midtones or highlights, no gamma curve and no per-channel level, so lifting detail out of an underexposed photograph is not something this page can do.
- Because the operation is uniform over every pixel, including the ones already at maximum, raising the amount pushes blown highlights further out of range instead of recovering them, and lowering it again does not restore what the encode already clipped.
- The arithmetic happens inside the browser filter rather than in code that can be read here, so the exact rounding is the engine's, and the output container is not selectable at all.
Tested and documented by itoolnet, the team that builds and maintains this site.