Make image background walls transparent while retaining shadows and texture

I have 60 images where I need the entire background wall to become transparent while preserving every bit of its existing texture and the natural, mixed hard- and soft-edged shadows that fall across it. The texture stays uniform from edge to edge, so once the wall itself has been knocked out the remaining alpha channel should still reveal its subtle grain and lighting nuances. I just need the finished file returned as a high-resolution PNG with transparency intact—no compression artefacts, no colour shifts, and no visible halo where the wall used to be. Attached a sample image.