What is photo compression — JPEG, WebP, AVIF, file size
What photo compression is: shrink JPG, WebP and AVIF file size, lossy vs lossless, and how to compress an image online.
Photo compression drops data you are unlikely to notice so the file shrinks. JPEG, WebP and AVIF are lossy for photographs; PNG is lossless and stays large on camera shots.
Quality sliders are not percents of file size. 80 on JPEG is not “80% of the original bytes”. Re-saving a JPEG many times stacks artifacts. Prefer the original when you still need to crop.
AVIF often wins on size at a given quality but support and encode time lag JPEG. For email and CMS, JPEG is the safe default. Transparency still needs PNG or WebP with alpha, not JPEG.
Lossy compression throws away detail a viewer may not notice. JPEG, WebP, and AVIF do this for photos. Lossless compression, typical of PNG, only packs repeated pixels and does not shrink a noisy photo much. Each extra save of a JPEG adds damage even at a high quality number. This page defines the idea. Running it on a file, or forcing PNG into JPEG, is a converter.
FAQ
JPEG or WebP?
WebP is usually smaller, AVIF smaller still. JPEG opens everywhere, including older mail clients.
Why is my PNG still large?
PNG can shrink, but photos usually get smaller as WebP or AVIF.