The extension JPG2 marks files containing a bitmap image in JPEG 2000 format.
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. Unlike JPEG, this metadata is not in EXIF format, but JPEG 2000 stores the same data as XML. Adobe's Extensible Metadata Platform (XMP) is also supported as a metadata format.
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.
There are different versions of the JPEG 2000 standard, not every program supports them all. Different programs also need a plugin to handle JPG2 files. Jpg2 files usually contain data in the first standard (Part 1) of the JPEG 2000 format.
The file extension JPG2 is used very rarely, changing the extension in jp2 can be helpful.
Most often resolving problems with opening JPG2 files is very simple. Just install an appropriate program that supports such files. All of the listed programs support JPG2 files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of JPG2 files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate JPG2 files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the XnView applications is not on the list, select "Browse" option in order to manually locate the directory where XnView has been installed.
Sometimes problems with opening JPG2 files may not lie with the application itself, but can arise due to other causes, such as: