Wirebook › Glossary › Lossy compression
What is lossy compression?
In one sentence: Packing that throws away some detail on purpose so the file gets smaller, like a JPEG photo or a blurry video call.
A little more
Lossy compression throws away detail you are less likely to notice so the file gets much smaller. A camera saving a JPEG drops tiny colour wobbles; a video call paints bigger blocks on a slow connection; an MP3 keeps the tune and skips faint overtones.
You cannot unpack what was thrown away. That is fine when the goal is a smaller photo or a call that still fits the pipe, and the wrong tool when you need every byte back (documents, source code, a master recording).
See it in action
- BonusWhy does zipping photos barely make them smaller?Guess which four suitcase items will squash — a repeating chorus, a letter, a camera photo and TV snow — then pack them with a real (tiny) compressor and see.7 min · interactive
- BonusWhy does a video call go blurry when the connection is slow?Dial a pretend video call's bandwidth thinner, spend a tiny 10-bit budget on eyes vs mouth vs wallpaper to still read a facial expression, then reveal the clear face.7 min · interactive
- BonusWhat happens when you squish a video too much?Squish a real (tiny) picture the way phones squish video: watch thin whiskers crumble first, then 8x8 blocks appear, then a splat.10 min · interactive
Do it for real
Free grown-up tools and guides on Tooltern, our sister site. They work in your browser and nothing is uploaded.