iCloud Drive to iCloud Photos

Hi, anyone know how to transfer photos from iCloud Drive to iCloud Photos? I’ve tried various different windows apps but they either won’t transfer them, or will not move whole albums. If I try to do it by downloading all albums then uploading to iCloud Photos it says some cannot be transferred because they can only be in JPG. I only ask as I have a few 1000 and while they are in iCloud Drive I cannot use the search functions for people etc as you can in iCloud Photos. Thanks.