Adjust Image Brightness & Contrast
100% private — runs on your device, never uploaded. Works offline once loaded.
Adjust the brightness, contrast and saturation of any JPG, PNG or WebP image with live sliders. Everything runs locally in your browser.
What the three sliders are actually doing
Brightness shifts every pixel's value up or down by a flat amount, making the whole image uniformly lighter or darker. Contrast stretches or compresses the range between the darkest and lightest pixels around the midpoint, so shadows get deeper and highlights get brighter (or the opposite, if you reduce it) — it's what gives a photo 'punch' rather than looking flat. Saturation scales how far each pixel's colour sits from grey, so pushing it up makes colours more vivid and pulling it down moves the image toward black-and-white, without changing how light or dark anything is.
When these adjustments actually matter
A backlit phone photo where the subject's face came out dark against a bright window benefits from raising brightness and contrast together. Product photos shot under warm indoor lighting often look washed out or dull online and need a saturation boost to match how they looked in person. Scanned documents or old photos frequently come out flat and grey, and a contrast increase alone can make faded text or details noticeably more legible.
- Correcting underexposed or overexposed phone photos before sharing
- Making product photos pop for an online listing
- Improving legibility of scanned documents or receipts
- Matching the look of a batch of photos taken in inconsistent lighting
Why extreme adjustments cause banding
A standard JPG or PNG stores only 256 shades per colour channel. When you push brightness or contrast a long way, nearby shades that were originally distinct can get mapped to the same value, and the smooth gradient in something like a sky or a cheek can start showing visible stripes — this is called banding, and it's a permanent side effect of stretching a limited set of values rather than a bug in the tool. Working from a higher-resolution, well-exposed original and making smaller adjustments avoids it almost entirely.
A quick tip
Adjust contrast in small steps after brightness, not before — fixing exposure first gives contrast a more accurate midpoint to stretch around, and you'll usually need less of it to get a natural-looking result.
Frequently asked questions
Will this reduce quality?
Minor adjustments keep quality high. Extreme changes may introduce some banding.
Are my images uploaded?
No — adjustments happen on your device.
Will adjusting these settings reduce image quality?
Small to moderate adjustments keep quality high. Pushing brightness or contrast to the extremes can cause visible banding in smooth areas like skies, since JPG and PNG only store 256 shades per channel.
Can I preview the changes before downloading?
Yes — the sliders update the image live on the canvas, so you see the exact result before you export it.
Does lowering saturation fully to zero give me black and white?
Yes — zero saturation removes all colour information while leaving brightness and contrast untouched, producing a standard greyscale image.
Will this work on a PNG with transparency?
Yes — brightness, contrast and saturation are applied to the visible pixel colours only, and the transparent areas stay transparent.
What's the difference between raising brightness and raising contrast?
Brightness shifts every pixel lighter or darker by the same amount; contrast stretches the gap between dark and light areas, so shadows and highlights move apart even if the overall average brightness barely changes.
Can I undo an adjustment after applying it?
You can reset the sliders back to zero before exporting to return to the original image, but once you've downloaded the adjusted file, the original values aren't recoverable from it.
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