Convert JP2 to JPG
JPEG 2000 was designed to replace JPEG and did not, except in the places that adopted it early and never left — archives, cinema, medical imaging and some scanners. If a file like that has landed on your desk, almost nothing on a normal computer will open it. This turns it into a JPG that everything will.
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Add to Chrome — freeDrop your JP2 file here, or click to browse
Up to 50 MB. Deleted automatically after 30 minutes.
What it does
- Opens a format almost no consumer software reads
- Encoded at quality 82, a number we publish
- Handles the lossless JP2 variant as well as the lossy one
- Nothing to install
How to use JP2 to JPG
- 1
Add the JP2
Drop it in. Files ending .jp2, .j2k or .jpf are the same family and are read the same way.
- 2
Encoded as JPEG
Quality 82. If the source was a lossless JP2, this is where the loss happens — see below.
- 3
Download the JPG
It opens in every browser, phone, editor and email client.
How it works
The JPEG 2000 codestream is decoded through OpenJPEG and re-encoded as a baseline JPEG at quality 82. No resampling, no resizing — only the codec changes.
The successor that did not succeed
JPEG 2000 is a better codec than JPEG by most measures, and it lost anyway. Understanding why explains where you find it.
It replaced JPEG's discrete cosine transform with a wavelet transform, which degrades much more gracefully: instead of the blocky squares a heavily compressed JPEG produces, a heavily compressed JP2 goes soft. It added a genuinely lossless mode, progressive decoding at multiple resolutions from one file, and support for enormous images.
What it did not have was a clear patent position at the moment browsers were deciding what to support, or decoders fast enough for the hardware of 2001. JPEG was already in every camera, browser and operating system, and "somewhat better" does not beat "already everywhere".
So it went where those advantages were worth the trouble anyway: archives, which need lossless masters; digital cinema, where it is the mandated codec for distribution; medical imaging, where detail is diagnostic; and some document scanners, where progressive decoding of huge page images matters.
If you have a JP2, it very likely came from one of those four.
Which target to pick
Choose JPG when the file is going somewhere ordinary — an email, a document, a website, a form. Universal, small, and good enough for anything viewed on a screen.
Choose PNG — /jp2-to-png — when the source is a lossless JP2 and you want to keep it that way, or when the image is a document scan with text in it, where JPEG's ringing around sharp edges is most visible.
Choose neither, and keep the JP2, if it is an archival master. The conversion is for a copy you are going to use.
Where the file probably came from
Knowing this changes what you should do with it, so it is worth a moment.
An archive or library. Deposit copies are usually LOSSLESS JPEG 2000, and this conversion introduces the first loss the image has ever had. Keep the original; treat the JPG as a working copy.
Digital cinema. DCP packages mandate JPEG 2000, and the files are enormous, lossless, and in a color space (XYZ) that a general converter cannot map correctly. If your file came from a DCP and the colors look wrong, that is why.
Medical imaging. Often JPEG 2000 inside DICOM. Converting for viewing is fine; converting for anything diagnostic is not, and the lossless route /jp2-to-png is the correct one if the pixels matter.
A scanner. Some document scanners default to JP2. These are the files where converting freely is entirely reasonable — there is no master being degraded, just an awkward default.
Examples
A scan from an archive
Libraries and repositories deposit in JPEG 2000. Anything you want to do with the file afterwards probably wants a JPG.
An image from a scanner
Some document scanners write JP2 by default and the software that reads it stays on the machine it came with.
Frequently asked questions
What is JPEG 2000 and why does nothing open it?
It is a 2000-era successor to JPEG built on wavelets rather than the discrete cosine transform, which gave it genuinely better quality per byte and a lossless mode. It never displaced JPEG because the licensing situation was murky at the wrong moment, decoders were slow on the hardware of the day, and JPEG was already everywhere. It survives where it was adopted early: archives, digital cinema, medical imaging, some scanners.
Will I lose quality?
Some, and how much depends on the source. JPEG 2000 has a lossless mode that many archives use, in which case this conversion introduces the first loss the image has ever had. If the source was lossy JP2 you are re-encoding already-compressed data, which loses a little more. Either way, at quality 82 it is invisible at normal viewing size — and if you want none of it, /jp2-to-png is lossless.
Should I convert or keep the original?
Keep the original, always, if it came from an archive or a scanner. A JP2 master may be lossless and is certainly the version with the most information in it. Convert for working, sending and viewing; the JPG is a copy for use, not a replacement for the deposit.
What about .j2k and .jpf files?
Same codec, different container. `.jp2` is the boxed file format with metadata and a color specification; `.j2k` is the raw codestream; `.jpf` is the extended JPX variant. All are read here. If a file will not open, the usual cause is not the extension but an unusual color space — some medical and cinema files use ones a general converter cannot map.
Does my file leave my computer?
Yes. JPEG 2000 decoding needs a codec library that runs on our server rather than in a browser. Your file and the result are both deleted within 30 minutes by a timer, and nothing is stored, indexed or examined — there is no account and no history.
Further reading
- Cropping a JPEG Re-Encodes the Part You KeptCropping feels subtractive — you are taking pixels away, not changing them — so the part you keep should arrive untouched. In a JPEG it usually does not, and the reason is the same one that makes rotation lossy.
- Rotating a JPEG and Back Changed 560,770 PixelsRotating a photo is not editing it. Nothing about the picture changes, only which way up it is — so it is reasonable to expect the pixels to survive. With most tools they do not, and the loss is the same kind a re-save costs.
- We Re-Saved a JPEG Twenty Times and Nothing HappenedEveryone has heard that a JPEG gets worse every time you open and save it, and most people have seen the artwork made by re-saving an image five hundred times to prove it. So we measured it properly. Re-saving at the same quality, twenty times, changed the image by nothing at all — and then we found the conditions where it degrades badly.