Image Brightness & Contrast
Drop an image below, move the brightness and contrast sliders and click Adjust. You can also set the output quality to balance sharpness and file size. Transparent images stay transparent. Everything happens locally in your browser — your image never leaves your device.
Read the guide: How to adjust image brightness and contrastInput
Negative darkens, positive brightens.
Negative softens, positive makes lights lighter and darks darker.
Higher quality keeps the result sharper. Transparent images are saved as PNG; photos as JPG.
Output
Processed locally in your browser — nothing is uploaded.
How the Image Brightness & Contrast works
- Your image is loaded into an in-browser canvas — nothing is uploaded.
- Brightness adds a fixed value to every pixel's red, green and blue channels.
- Contrast scales each colour's distance from the midpoint (128) using a standard contrast factor.
- The adjusted canvas is re-encoded at the output quality you choose (transparent images become PNG, photos become JPG) and the before/after size is shown.
Useful tips
- Start with small adjustments (±20) — large values clip colours and wash out detail.
- Increase contrast to make a flat photo pop, then nudge brightness to fix overall lightness.
Frequently asked questions
Is my image sent to a server?+
No. All adjustment happens entirely in your browser using a canvas. Nothing is uploaded or stored.
How do brightness and contrast work?+
Brightness adds a fixed amount to every pixel's red, green and blue channels. Contrast scales how far each colour sits from the midpoint (128), making lights lighter and darks darker. Both run per-pixel on a canvas in your browser.
Will transparency be preserved?+
Yes. Only the RGB channels are adjusted; the alpha channel is untouched, so transparent areas stay transparent and the result is saved as PNG.
What does the output quality setting do?+
For opaque photos it sets the JPEG encoding quality — higher keeps edges sharper at a larger file size, lower shrinks the file. Transparent images are saved as PNG, which is lossless, so the quality slider doesn't apply to them.
Related guides
How to compress JPG images
Large JPG files slow down websites and fill up storage. This guide explains how JPG compression works, how the quality setting trades size for sharpness, and how to pick a sensible level for photos and graphics — all using a free tool that runs entirely in your browser.
How to compress PNG images
PNG files are large because the format is lossless and keeps every colour and pixel. This guide explains how PNG compression works, how reducing colour depth shrinks the file while preserving transparency, and how to choose a sensible level — all using a free tool that runs entirely in your browser.
How to compress WebP images
WebP produces smaller files than JPG and PNG while supporting transparency, but it can still be trimmed further by re-encoding at a lower quality. This guide explains how WebP compression works, how the quality setting trades size for sharpness, and how to pick a sensible level — all using a free tool that runs entirely in your browser.
How to reduce image file size to a target
Sometimes you need an image under a specific size — for an upload limit, an email attachment or a web budget. This guide explains how target-size optimisation balances quality and dimensions to hit a file-size limit, and how to reduce an image to 100 KB, 500 KB, 1 MB or 2 MB — all using a free tool that runs entirely in your browser.
Related tools
Compress JPG
Compress JPG images and reduce file size — choose your quality level, all in your browser.
Compress PNG
Compress PNG images and reduce file size while preserving transparency — all in your browser.
Compress WEBP
Compress WebP images with adjustable quality — all in your browser.
Upscale Image
Upscale an image by 2×, 3×, 4× or a custom factor while keeping the best possible quality — all in your browser.
