Leawo PhotoIns BG Remover is one part of their Photoins program -- it also offers enhancing & enlarging, all with assistance from AI [ leawo.org/photoins/ ]. One thing most AI photo apps have in common is their large size -- the actual setup file [the GOTD setup is just a downloader] is *just* under 1GB, while the installed app is over 2GB. It adds a service, phymem_ext64.sys, plus folders in ProgramData, Pictures, Users\ [UserName]\ AppData\ Local & Roaming. Aside from the service, I only recorded one new key in the registry.
To replace the background you 1st *select* the main object(s) in the photo -- once you have your selection, copy / pasting it onto another background is trivial. Making selections, & often masks from those selections, is a HUGE thing in photo editing, so editing apps all have a set of tools just for that -- those tools are often used as a selling point, as companies try to outdo the competition. The hard part is getting the edges of a selected object right, especially if there's noise in the photo, since the color of the pixels at that edge tend to blend. Worse case you get an edge that looks like steps or stairs, but you also have to watch out for stray pixels the same color as the immediate background [fringing]. Hair is often talked about as the hardest thing to select, since a stray hair may be less than a single pixel wide. Common techniques include feathering the selection, moving the selection's edges toward the object, shrinking it by one or two pixels, even drawing in your own hair using custom brushes, while editing apps can include defringing tools that look for misplaced colors at the edge.
The advantage of AI in photo editing is that it can recognize the different things in your photos. It knows what a face looks like, and has a good general idea of what the other things common in photos are. That helps with auto selecting a person, or an animal like a horse, but knowing what to look for does absolutely nothing, has no effect on how good those edges are. Photoshop has automated & semi-automated AI selection tools, but they usually require a 2nd step, & sometimes a third to refine the edges -- the goal is to save a pro [who gets paid by the photo] little bits of time here & there, since that can mean more photos edited & thus more $.
Now the proper way to do composites, e.g., background replacement, is to match the colors, exposure, lighting, shadows etc. in a photo editing app, rather than something like Leawo PhotoIns BG Remover, but I realize not everyone wants [or needs] that much realism. In those cases I recommend Franzis Cutout instead of the Leawo app -- if you missed it the last time it was on GOTD, you can get v.7 here free: projects-software.com/giveaway-deal . I'm recommending Franzis because AI sometimes glitches, AI isn't really needed for background removal / replacement, Franzis built their entire rep on photo editing, with years of experience, and finally, with the Leawo app that's a very large portion of your disk storage you're giving away.