Is there any good sofware available for linux for creating HDR images?
For panoramic HDRs and images where your (bracketed) exposures are likely to be jittery,
Hugin is IMHO the only way to go.
Although, I tend to tell it to emit HDRs, and then I import the generated HDR into QtPfsGui for the final tone-mapping to JPEG, and then do minor touch ups ( Cropping, bordering, basic levels ) with Gimp.
There are lots of techniques people use in Gimp and Photoshop alike to approximate HDR effects, but they are in my opinion Not HDRs, because they don't permit you to emit 32bit-floating point colour files of the singular image that contains the full dynamic range.
Also, some programs such as Raytracers can import HDR Images ( they are notable because they have the .hdr or .exr extension most of the time, any file you create with .jpg is not HDR, its just a tonemapped HDR down to LDR ) and use them as environmental lighting maps, to produce glossy reflections like this
I don't have a lot of experience on this, but you can use the gimp, there are some tutorials online.
ImageMagick command-line graphics library supports Cineon and DPX files. The ImageMagick offshoot/fork GraphicsMagick, on the other hand, relegates Cineon to "legacy" format status, has a far more complete DPX read/write implementation, supports LogLuv TIFF, and lists OpenEXR on its "to do" list. (ex :http://www.imagemagick.org/script/examples.php)
CinePaint handles the most: Cineon, DPX, OpenEXR, and LogLuv TIFF.
The GIMP can handle Cineon and DPX through plugins (and the Cineon plugin is more recent than the DPX plugin).
Krita supports OpenEXR natively, and inherits the ability to read Cineon and DPX from its ImageMagick dependency.
HDRIE and HDRShop are both multi-format HDR image editors
exrtools supports (surprise!) OpenEXR images, while pfstools supports OpenEXR and RGBE.