File Extension J2K

  • Full name
    JPEG2000 Code Stream Image
  • Developer
    Joint Photographic Experts Group
  • Popularity
Have you encountered a problem with a J2K file? Don’t you know which program opens a file with this extension? You will find all the information you need about working with a J2K file here. In the further part of this page we have added a list of programs that should open your J2K file. It is enough you choose a proper application for your operating system, download and install it.


A J2K file contains bitmap image data in JPEG 2000 format. However, it only contains the code stream, ie the data stream that contains the pure image data.

JPEG 2000 describes both a compression method and thus a codestream (data stream) as well as a file format. While the data stream is sufficient to decode the image, the file format includes additional information such as metadata.

JPEG 2000 is a digital image compression technique that provides both lossless and lossy compression. It has some advantages over JPEG. Image quality is better at high compression rates and some limitations no longer exist. Eg image size, color depths or support for alpha channels (for transparency). However, this is offset by the licensing-related situation and a significantly higher demand for computing power.

The pure data stream (codestream) is not intended to be stored in files, so no uniform extension is required. The endings jpc, j2c and J2K are common.

There are different versions of the JPEG2000 standard, not every program supports them all. Different programs also need a plugin to handle J2K files.

Programs which can open a J2K file

How to open a J2K file? Advice and guidance

Absolutely most often appearing reason that prevents you from opening the J2K file is the lack of a proper application to support it in your operating system. It is notably the first thing you need to address. When one of the programs to support a J2K file from the list is already installed, you can try to rerun the file. The system should display a message asking you to choose a primary application to support J2K files. At this point we are looking for disk space where the application was installed in and we can link it with a J2K file. Since then, our operating system will use the selected program to support all J2K files.

Other issues

Despite the described problem with J2K there may be many more problems. If the existing operations were not effective, get involved with the following matters:

- verify that the J2K file is not damaged and that it has been downloaded or copied in whole
- verify that the file has a file extension that has not been intentionally changed (for example, if it do not contain other information than its extension suggests)
- make sure again whether the J2K file type is linked in the operating system with a proper program
- make sure that the file is not infected with a virus and you have up to date software and drivers.

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