Image Brightness & Contrast

About image tools

Most image problems come down to three things: the format (JPG, PNG, WebP), the pixel dimensions, and the compression level. JPG is great for photos because it discards detail the eye barely notices. PNG is lossless and supports transparency, which makes it ideal for logos, screenshots and diagrams. WebP is a newer format from Google that is usually smaller than both, but some older apps still refuse to open it.

These tools use the drawing canvas built into every modern browser. Your image is decoded locally, redrawn at the size or format you choose, and handed back as a download. Because nothing is uploaded, they work offline once the page has loaded and they are safe to use with personal photos and ID scans.

A useful rule of thumb: decide the display size first, then the format, then the quality. A 4,000-pixel phone photo shown 800 pixels wide on a website wastes about 96% of its pixels, and no compression setting can fix that as well as resizing can. For photos, JPG or WebP at 75–85% quality is usually indistinguishable from the original; for images with text, sharp edges or transparency, PNG keeps them crisp. Redrawing an image through the canvas also removes hidden EXIF metadata — camera model, date and sometimes GPS coordinates — which is a privacy benefit when you post photos publicly.

Popular ways people use image tools

• Shrinking product photos so an online shop or marketplace listing loads quickly on mobile phones.
• Resizing a portrait to the exact dimensions a passport, visa or job-application form demands.
• Converting WebP images saved from websites into JPG so that older software and printers accept them.
• Creating a QR code for a restaurant menu, a Wi-Fi network, an event poster or a business card.
• Compressing holiday photos before attaching them to an email that has a strict size limit.

How we build and test our free tools

Every tool in this collection is built and tested by The Curator team. Before a tool is published we check it against known reference results — textbook loan schedules, standard test vectors for hashes, sample files for conversions — and we re-check it whenever browsers change. Each page explains the method so you can verify the answer yourself rather than take it on trust.

The tools run as JavaScript inside your browser tab. When you choose a file, your browser reads it from your disk into memory; the tool processes it and gives you the result as a download. No copy is sent to us or to anyone else, and nothing is kept after you close the tab. That is why these tools are safe for personal documents, and why they keep working on a slow or interrupted connection once the page has loaded.

The collection is free because it is supported by advertising on these guide pages. We never charge for a tool, never add watermarks and never sell what you type. If something doesn't work as described, or you would like a tool we don't have yet, please contact us — new tools are added in regular batches based on what readers ask for.

Frequently asked questions

What do the numbers mean?

Brightness adds up to ±255 to each colour channel; contrast stretches or compresses values around the midpoint.

Does it keep transparency?

Yes — only colour channels are changed.

Is my input stored or sent anywhere?

No. Everything runs inside your browser tab and disappears when you close it.

Is the Image Brightness & Contrast really free?

Yes. There is no account, no trial and no watermark. The Curator is supported by advertising on its guide pages, never by charging for tools or selling your data.

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