Gimp is loaded on EVERY linux computer at savannah college of art and desing . i use it occasonally . but it is usless for HDR, 16 and 32 bit image editing . and it's cumbersom. it also dosn't have half the features that photoshop does . automated phtotmerge . raw image handling , not nearly enough filters . and ther are other HDR and stiching softwares avalable for linux for free.