JPEG Network Graphics (.jng)

The JNG (JPEG Network Graphics) file format is an innovative hybrid that merges the compression benefits of JPEG with the transparency feature of PNG. Originating from the PNG Development Group's efforts, JNG is part of the MNG (Multiple-image Network Graphics) suite. Its core function is to embed JPEG-compressed imagery into a PNG-like file, complete with an alpha channel for transparency. This dual capability enables the creation of images that are both lossily compressed, akin to JPEG, and transparent, like PNG.

JNG's utility shines in scenarios requiring static images within animated sequences, linking it to the broader MNG framework. Typically, a JNG file represents a single animation frame within an MNG sequence. While PNGs are known for lossless compression, JNG opts for lossy compression, which can introduce JPEG-like artifacts but also reduces file size significantly. Encapsulating JPEG-compressed data within a PNG wrapper, JNG files may include transparency through an alpha channel, though this feature is not consistently employed across all JNG files.