Batch cropping scanned album photos

I have a slow scanner, so I took photos of thousands of physical album photos with my cell phone. I was hoping that Photoshop was smart enough to detect the edges of the album photos and automatically split and crop them into separate files. Alas, that was not the case, so I used the slice tool to manually split these album photos one at a time. However, I am still left with thousands of photos that need to be cropped because the album page is still visible. Is there any way to automate the process? Is there any way to get Photoshop to detect the edges of the physical photo? Or am I stuck cropping thousands of photos manually? I have posted several of these photos for your illustration.

By the way, the straighten and crop feature did not work at all--it would convert a single album page with 5 actual photos into 40 image files because it captured every slice of the page--that's why I resorted to the slice and export tool.