toGainMapHDR, which convert png, tiff etc. HDR file to Adaptive HDR (gain map heic file) / ISO HDR (PQ or HLG curve image). The program will read a image as both SDR and HDR image, then calculate ...

You might want to open two files in two separate windows to compare them. Also, if you want to edit two files simultaneously, you need to open them separately. That is why you can change Notepad ...