Widespread and varied uses for amusement and education evolved throughout the century. By 1900, photographic images on glass had replaced hand-painted images, but the black-and-white photographs were sometimes hand-colored with transparent dyes. The production of lantern slides had become a considerable industry, with dimensions standardized at 3.25 inches high by 4 inches wide in the US and 3.25 inches square in the UK and much of Europe.