Adjust Brightness

What is Adjust Brightness?

Brightness is the average lightness of an image, the value you would get if you blurred the entire photo into a single flat gray. Brightness adjustment shifts every pixel up or down on the tonal scale by the same amount, so a +20 shift adds 20 units of value to every red, green and blue channel. This is the simplest possible exposure correction: it cannot recover blown-out highlights or pull detail out of crushed shadows, but it is exactly the right tool when a photo is just a little under- or over-exposed. This tool runs the adjustment on an HTML5 Canvas in a single pixel pass, so even a 20-megapixel image previews instantly as you drag the slider. The slider ranges from -100 to +100, where ±10-20 is a subtle correction (the kind a phone gallery app does automatically), ±30-50 is a deliberate stylistic choice, and ±70+ pushes the photo into either silhouette or overexposed white territory.

Why use this tool?

Adjustment runs on the GPU via Canvas filter where available, falling back to a CPU pixel-pass on older browsers. Either way, even a full-resolution camera photo previews in well under a second. The live slider gives you direct visual feedback rather than the guess-and-export cycle of many photo editors. The pixel-pass is non-destructive until you click download, your original file is never modified and no upload happens. Output keeps the input's format, dimensions and metadata. PNG transparency is preserved through the adjustment.

Common use cases

The clearest case is a phone photo taken in tricky light. Indoor portraits often come out a touch too dark because the camera metered the bright window in the background. A +15 brightness pass restores the face to a natural exposure. Outdoor noon photos can do the opposite, the camera underexposes to protect the sky, leaving the foreground in shadow. Other workflows: lifting screenshots that look fine on a phone but too dim on a laptop screen; rescuing scanned documents where the original page was off-white or gray; making thumbnail images pop in social-media feeds; producing a deliberately bright, airy look for product photography. If a photo also looks flat, contrast adjustment usually does more work than brightness, see our Adjust Contrast tool. For colour-cast fixes (warm/cool, magenta/green), use Adjust Colors instead, brightness affects all channels equally and cannot correct color shifts.

How to use Adjust Brightness

1. 1Drop a JPG, PNG or WebP image into the upload area
2. 2Drag the brightness slider, the preview updates in real time
3. 3Stop when the result looks right, ±15-30 is typical, ±50+ is dramatic
4. 4Download the result in the same format as the source

Frequently asked questions

How is brightness different from exposure in a camera app?

Brightness is a flat shift applied uniformly to every pixel. Camera exposure controls aperture, shutter and ISO, which change how much light the sensor captured in the first place. After-the-fact brightness cannot recover information that was not captured (blown-out skies stay blown out), but it is the right tool for adjusting how an already-captured image appears.

Can I brighten a very underexposed photo back to looking normal?

Partially. A photo that is 1-2 stops underexposed brightens cleanly. A photo that is 4+ stops underexposed reveals heavy noise in the shadows as you lift them, since the shadow data was barely above the sensor noise floor. For severely underexposed photos, also use Adjust Colors to desaturate the noise.

Will brightening introduce noise or banding?

On a high-quality original, no visible change. On low-light phone photos or aggressive shadow lifts, yes, the shadow noise that was hidden in the dark becomes visible when those values are pulled up the tonal scale. Apply a small Blur Image pass (radius 1-2) to soften noise after a heavy brightness lift.

Why does the photo look washed out after I brightened it a lot?

Because uniform brightness lift compresses the upper tonal range, mid-tones move toward white but pure-white pixels cannot go any higher, so contrast drops. The remedy is to follow brightness with a small contrast boost using our Adjust Contrast tool, which restores the punch.

Does this work on transparent PNGs and animated GIFs?

PNG transparency is fully preserved, the alpha channel is independent and untouched. Animated GIFs are handled as still images, the first frame is adjusted but the animation is lost on export. For animated output you would need a video-style editor.

Are my files uploaded to a server?

No. The brightness adjustment runs entirely in your browser on a Canvas. The file is read once, adjusted in memory, and offered for download. No server is involved at any point, which is why the tool is safe to use on personal photos, screenshots of private information, or any image you would not want uploaded.

1. 1If you are editing a batch of photos shot in the same lighting conditions, find the right brightness setting on one, then apply the same numeric shift to the rest in a batch run via Bulk Convert Images.
2. 2For thumbnails and feed previews, lean about +10 brighter than feels right on a calibrated monitor. Phone screens display darker than desktops, and a slightly over-bright export looks correct on the device most viewers will use.
3. 3Brightness combines with the auto-exposure of HDR display modes on phones. If the original was shot in HDR, a +20 brightness shift can land much brighter on the viewer's device than your monitor suggests, test on a phone before committing.

How does it compare?

Most phone editors offer a single 'Brilliance' or 'Auto' slider that bundles brightness, contrast and saturation together. This tool separates them so you can tune brightness alone without colour shifts you did not ask for.

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