Image Exposure

A stop is a doubling or halving of light. Plus one stop doubles the light in every pixel and minus one stop halves it, plus two stops multiplies it by four and so on. Photographers use stops to describe aperture, shutter speed and ISO changes.

Image files store values with a gamma curve, so doubling the stored number is not the same as doubling the light. The tool converts each value to linear light with the sRGB curve, multiplies it and converts back, which matches how a real exposure change looks.

A mid gray of 118, which is about 18 percent of white in linear light, becomes about 162 at plus one stop and about 85 at minus one stop. Bright values move less in stored numbers, and anything that would exceed white is clipped.

Any value from -5 to 5 stops, including decimals such as 0.3 or -1.7. The default is plus one stop. Values beyond two stops in either direction are strong and are mostly useful for creative effects.

Yes, highlights that already sit near white are clipped when the exposure goes up, and detail there cannot be recovered. If only the shadows are too dark, Image Levels or Image Local Contrast may give better results.

Brightness tools usually scale or shift the stored values directly, while exposure scales the actual light. Exposure keeps colors and the relation between tones more natural, especially when brightening dark photos.

All three channels are scaled by the same factor, so hues stay the same. Strong increases can make bright colors clip toward white and lose saturation.

Yes, the alpha channel is not changed. Only the red, green and blue values are adjusted.

JPEG, PNG, GIF, WebP, TIFF and AVIF images up to 5 MB are supported. Animated files use their first frame and images over 4000 pixels on a side are scaled down to fit. The output is PNG.

Raising exposure reveals what the file contains, but an 8-bit JPEG has few levels in deep shadows, so heavy boosts show noise and banding. Moderate corrections of one or two stops usually look clean.