# JPEG **JPEG (Joint Photographic Experts Group)** is a lossy image compression format that works by breaking an image into 8×8 pixel blocks, converting each block into frequency data via the Discrete Cosine Transform (DCT), then discarding high-frequency detail the human eye is least likely to notice. The result is dramatically smaller files — typically 10:1 compression — at the cost of some original information that can never be recovered. ^overview > [!example] > A quality setting of 80–90 is usually invisible to the eye. Drop below ~40 and you'll start seeing blocky "macroblocking" artifacts — especially around sharp edges, text, and high-contrast areas. Re-saving a JPEG repeatedly compounds the loss each time.