File format HDR also described as RGBE is graphical format created by Gregory Ward Larson. Format uses tricolored spectrum called RGB, where it saves information about shades of color in certain pixels. It is lossless format, which is today used by many programs. It was released on 4th March 2009. It was released for program Radiance, where it is used.
Originally program Radiance was created in 80s of 20th century. It was protected by license and parts of this program weren´t allowed to be shared. In 2002 was created less proteting rights, which led to the expansion of this program. Later on in 2009 was created HDR format for this package that allowed creation of pictures.
To open files created in this format you can use Adobe Photoshop, which is unfortunately not free. However there is trial version for free that stays for 30 days.