What is a JP2 file?

"What is a JP2 file? And what do I do with it after I download it from your site?"

These two questions arise frequently with users of Botanicus, so we thought we would make a blog entry to address the topic.

JP2 is the file extension for the JPEG2000 image file format. Think of it as the next generation of the more commonly known JPEG file format. It was introduced in the year 2000 (hence the name), and in principal, it's very similar to JPEG in that they are both compressed image file formats. Because of the compressed file size, JPEG's have long been one of the web standards for displaying images and graphics. The major downfall to JPEG images is that the compression has a negative effect on image quality. The more an image is compressed when saving a JPEG, the smaller the file size will be but also the more the quality deteriorates. JPEG2000 files on the other hand can be compressed to much smaller file sizes with far less deterioration in image quality, which makes it an ideal format for us to serve images to the users of Botanicus.

JP2 files, however, have a disadvantage of their own. Many software authors have failed to embrace this new format yet, and thus programs have been slow in development to offer the ability to open the files. This creates a bit of a challenge for Botanicus users who want to view the files locally on their computer after downloading... Luckily there are four options we recommend for opening JP2 files (three of which are free):

• IrfanView - A freeware image viewer with limited image editing capabilities.
• Adobe Photoshop - Current versions offer support for JP2 files, however you will need a plug-in to open JP2 files in older versions.
• MrSID Decode - A free utility available for download from Lizardtech that allows for the decompression of JP2 files to TIF files.
• ExpressView browser plug-in - A free downloadable plug-in also available from Lizardtech for standard browsers (including Safari for Mac users) that allows JP2 files to be resaved to other more readily usable formats (JPEG, TIF, etc.).

There are numerous other options available as well (especially as support for JPEG2000 files continues to grow). For more information on other programs that can open JP2 files, please visit the "Application support" section of the Wikipedia entry for JPEG2000. There you will find an extensive list of other popular programs that currently support the JPEG2000 file format.

Mike Blomberg
Imaging Lab Coordinator
Missouri Botanical Garden