JPEG 2000 file format (.jp2)

What is a JPEG 2000 file?

In short: A JPEG 2000 file (.jp2) is an image file in the JPEG 2000 format. JPEG 2000 uses wavelet compression rather than the block-based method of ordinary JPEG, which means it degrades into softness rather than into visible squares. It can be converted to JPG, PNG or WEBP for free in a web browser with iHateFiles, without uploading it.

Published in 2000 as the JPEG committee's successor to the original JPEG.

JPEG 2000 uses wavelet compression rather than the block-based method of ordinary JPEG, which means it degrades into softness rather than into visible squares. It can be lossless or lossy in the same format, and a single file can be decoded at several resolutions.

What JPEG 2000 is good at

• No blocky artefacts, even at aggressive compression
• Lossless and lossy modes in one format
• Progressive decoding at multiple resolutions

Where JPEG 2000 falls short

• Browsers never adopted it, apart from Safari
• Slow to encode and decode
• Patent uncertainty in its early years killed its momentum

When to use JPEG 2000

You will meet JPEG 2000 in medical imaging, digital cinema and archives. For anything on the web, use WEBP or AVIF instead.

How to open a JPEG 2000 file

Medical and archival software, Safari, and professional imaging tools.

The thing that usually goes wrong

It is technically better than JPEG and lost anyway. Support, not quality, decided it.

Inside a JPEG 2000 file

JPEG 2000 was designed in 2000 to replace JPEG and comprehensively failed to, despite being better at almost everything. It uses a wavelet transform rather than the discrete cosine transform, which means it degrades into softness rather than into blocks, and it can do lossless and lossy compression in the same format.

Its most useful property is that a single file is inherently multi-resolution. A decoder can read the first fraction of the data and produce a thumbnail, read more and get a preview, read it all and get full resolution — without the file containing separate copies. That is why digital cinema and archives adopted it.

It lost the web because it arrived with patent uncertainty at exactly the wrong moment, and because JPEG was already good enough and universally supported. Safari renders JP2; Chrome and Firefox never implemented it.