To help Wall Street buy tens of thousands of houses, Martin Kay and his colleagues taught a computer to spot a sunny kitchen.

Ever since last decade’s foreclosure crisis, institutional investors have been gobbling up single-family houses and becoming landlords. They have criteria just like individual buyers: three or more bedrooms, two baths, a garage, good schools, low crime, high rental yields—and bright, sunlit kitchens. Unlike them, investors buy in volume and don’t have time to go to thousands of showings.

Enter...