One of the easy ways to set the Gamma for Trans, bump and displacement maps is to use the 'materialmods script' which comes with Poser under the the scripts drop down (Next to Help).  If you select it chose 'Change Gamma" the next pop up will ask for the setting, in this case 1, the drop down on the next pop allows you to select either the current material, current figure or all Props and Figures, select the later and on the last pop up select all of the above.  Don't select all materials as you want the Gamma for the image maps set above this, usually 2.2.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.