Adjust the Brightness and Contrast of a Photograph

About the Brightness & Contrast Editor

Two controls are offered, and both run from 20 to 200 percent with 100 meaning no change. Brightness lifts or lowers the whole image evenly, which is the fix for a shot that came out too dark. Contrast pushes the light and dark areas further apart or pulls them together, which is what a flat, hazy or washed-out picture needs. They work independently, and the usual sequence is to correct exposure with brightness first, then restore punch with contrast.

The preview updates as you drag either slider, so the adjustment is made by eye rather than by number. Several images can be corrected together under one pair of settings, which suits a batch shot in the same conditions. As with everything here, the adjustment is computed in the browser, which is what makes this usable for photographs that are evidence or records rather than something you would post publicly.

Key Features

• Two independent sliders: Brightness and contrast are separate controls, each spanning 20 to 200 percent around a neutral 100.
• Neutral centre point: Both default to 100, so you always know where no-change sits and can return to it.
• Immediate visual feedback: The image redraws as you drag, making a subtle correction far easier to judge than typing values.
• Consistent batch treatment: Apply one pair of settings across a set of photographs taken under the same lighting.
• Export format control: Keep the input format or write PNG, JPG or WebP with a quality setting.

How to Use the Brightness & Contrast Editor

1. Add the photograph that is too dark, too bright or too flat.
2. Correct the exposure first using the brightness slider.
3. Then adjust contrast to restore separation between the light and dark areas.
4. Export, or add more images to treat the whole batch the same way.

How It Works

Both adjustments are passed to the browser's imaging pipeline as a chained filter on the drawing context, applied in a single pass as the source is painted onto the output canvas, so even large photographs respond instantly. The significant limitation is that neither control can recover information that is not there. An area already clipped to pure white holds no detail to bring back, and raising brightness simply turns it grey rather than revealing a sky; the same is true of shadows crushed to black. There is also no curves or levels control and no separate handling of shadows and highlights, so both sliders act on the whole tonal range at once.

When You Need It

A facilities manager reviewing an out-of-hours incident pulls stills from a camera covering a loading bay, and they are far too dark to show what happened. Lifting the exposure and adding contrast makes the sequence usable in the incident report. Those frames show identifiable people going about their work, which makes them personal data, so running them through a free photo editor to brighten them would create exactly the kind of uncontrolled disclosure the security policy exists to prevent. Surveyors lightening photographs of unlit roof voids and technicians documenting equipment in poorly lit plant rooms adjust for the same practical reason.