About the Brightness & Contrast Adjuster
This lightens or darkens a photo and adjusts its contrast, with a live preview so you can dial in the look. It's the quick fix for an underexposed (too dark) or washed-out (too flat) picture — rescuing a dim indoor photo, making a faded scan pop, or toning down an overexposed shot. Slide the controls until it looks right and download the result.
How it works
The image is drawn to a canvas with the browser's brightness and contrast filters applied, both as percentages. Brightness above 100% lightens and below 100% darkens; contrast above 100% makes darks darker and lights lighter (more punch), while below 100% flattens the tones. The preview updates live as you move the sliders, so you see the effect immediately, and the adjusted image downloads as a PNG.
Assumptions and behaviour
- Brightness and contrast are percentages, with 100% meaning no change; you adjust each independently.
- Changes preview live on the full image.
- The adjustment is applied to the whole image uniformly (a global adjustment, not selective).
- Output is PNG at the original dimensions.
Limitations
- It can't recover blown-out or crushed detail. Areas that are pure white (overexposed) or pure black (underexposed) in the original hold no information, so brightening or darkening won't bring back detail that isn't there.
- These are global adjustments — they affect the whole image evenly, not specific regions, and there's no curves, levels, shadows/highlights or colour balance.
- Pushing the sliders hard can introduce banding or clipping in smooth gradients.
- Output is PNG, so an adjusted photo won't be as small as a JPG — convert or compress afterwards if size matters.
Privacy
The adjustment runs entirely in your browser with the Canvas API. Your image is never uploaded or stored.
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