JPX file extension is one of the extensions used for data stored in JPEG 2000 format. It contains compressed graphical data, and is a improved version of the JPEG encoding standard. Images stored in JPX files offer better quality than those stored in JPEG format without changes to the image size.

JPEG 2000 format is not very popular, mainly due to high computational complexity of decompression method it uses. JPEG 2000 format is commonly used as a part of Digital Cinema Package (DCP).