High　Dynamic　Range　(HDR)　images　improve　visual　quality　by　representing　a　wide　range　of　luminance　in　real　world.　HDR　Image　Quality　Assessment　(IQA)　is　essential　in　HDR　processing　technologies.　This　work　focus　on　the　IQA　for　the　HDR　applications　represented　by　HDR　compression.　Towards　designing　IQA　for　these　tasks,　user-end　display　information　should　not　be　considered,　given　that　these　tasks　only　focus　on　the　media　intrinsic　features.　However,　most　existing　HDR　metrics　are　associated　with　display　luminance,　hence　they　can　not　handle　IQA　during　HDR　processing.　In　this　work,　we　find　that　it　is　possible　to　evaluate　HDR　image　quality　without　prior　knowledge　of　luminance　for　display.　Based　on　this,　we　proposed　a　low　complexity　Display-Independent　Gradient　Magnitude　Similarity　(DIGMS)　metric.　Experimental　results　demonstrate　that　the　proposed　DIGMS　outperforms　the　state-of-the-arts　in　HDR　IQA.　This　work　opens　up　a　new　perspective　for　designing　IQA　algorithms　for　HDR　images.