Brightness

Brightness is the most common fix a photo needs, and usually the simplest to get wrong by overcorrecting. Shots taken indoors under weak lighting, backlit portraits where the subject is a silhouette against a bright window, or screenshots that came out darker than the screen actually looked all share the same problem: the exposure was set (or the sensor guessed) too low for what you actually wanted to see. This tool gives you one slider, moving from 0% (pure black) through 100% (the original, untouched image) up to 200% (heavily lifted), with the result rendered live as you drag.

Under the hood, this uses the browser's own canvas brightness filter rather than a hand-rolled pixel loop — it's the same operation professional editing software calls "exposure" or "brightness" at a basic level: a uniform multiplier applied to every pixel's lightness. That makes it fast even on large photos, but it also means it's a blunt instrument compared to a real curves or levels adjustment — pushing brightness too far will wash out highlights or crush shadow detail rather than selectively recovering them. For a photo that's dark in some areas and fine in others, brightness alone won't save it; for a photo that's evenly too dark or too light, it's exactly the right tool.

Everything runs locally: the image is decoded, adjusted, and re-encoded entirely in your browser using the Canvas API, and nothing is ever uploaded anywhere. If you want to adjust more than one thing at once — brightness alongside contrast, saturation, hue, or sharpness — the combined Image Adjustor has all five sliders in one place.