Image compression reduces file size by removing data the human eye barely notices. Done well, you can cut a photo's size by 60–80% with no visible difference. Done badly, you get muddy gradients and blocky artifacts.
Lossy vs lossless
There are two families of compression:
- Lossy (JPG, WebP, AVIF) throws away some data permanently. Best for photos.
- Lossless (PNG, WebP lossless) keeps every pixel exact. Best for logos, screenshots and line art.
Rule of thumb: photos → lossy, graphics with sharp edges → lossless.
A simple workflow
- Start from the highest-quality original you have.
- Pick the right format for the content (photo vs graphic).
- Aim for quality 75–85 for lossy formats - the sweet spot.
- Compare before/after at 100% zoom before you ship.
Why in-browser matters
With Toolknot's image compressor everything runs locally in your browser, so your photos never leave your device. Drop a file, pick a quality level, and download the optimized result in seconds.
| Format | Best for | Transparency |
|---|---|---|
| JPG | Photos | No |
| PNG | Graphics | Yes |
| WebP | Both | Yes |
That's it - sharper images, smaller files, and nothing uploaded to a stranger's server.
Frequently asked questions
Does compressing an image reduce its quality?
Lossy compression removes some data, but at quality 75–85 the difference is invisible to the eye while file size drops 60–80%. Lossless compression keeps every pixel exact.
What is the best format for compressing photos?
Use JPG or WebP for photos. WebP typically produces smaller files than JPG at the same quality and also supports transparency.
Are my images uploaded when I compress them on Toolknot?
No. Toolknot's image compressor runs locally in your browser, so your images never leave your device.
