JPEG
Thirty years of photos in 8×8 blocks.
Where it came from
JPEG was published in 1992 by the Joint Photographic Experts Group — an ISO/IEC committee that spent years balancing quality against the storage realities of the early 90s (a CD held ~650 MB). It became the universal photo format and stayed there for three decades.
How it works
The image is cut into 8×8 pixel blocks. Each block goes through the discrete cosine transform (DCT), turning pixels into frequency coefficients; high frequencies (fine detail) get quantized away — that's where the size savings and the familiar 'blocky' artifacts come from.
Chroma subsampling halves color resolution because eyes are worse at color than brightness. Quality setting (roughly 60–85) is the sweet spot for photos.
JPEG has no alpha channel — transparency requires PNG/WebP/AVIF. UWC flattens transparency to white when producing JPEG, exactly like browsers do.
Convert JPEG images
Turn JPEG into WebP or AVIF for smaller files, or into PNG when you need lossless editing.