Read high dynamic range (HDR) image
hdr = hdrread(filename)
hdr = hdrread(filename) reads the high dynamic range (HDR) image from the file specified by filename. hdr is an m-by-n-by-3 RGB array in the range [0,inf) of type single. For scene-referred data sets, these values usually are scene illumination in radiance units. To display these images, use an appropriate tone-mapping operator.
 Larson, Greg W. "Radiance File Formats"http://radsite.lbl.gov/radiance/refer/filefmts.pdf