1. A display apparatus that displays an image, comprising: image converting means for converting a photographed image signal, which is an image signal from photographing means for photographing an object, into a high-quality image signal of an image higher in quality than an image corresponding to the photographed image signal according to an arithmetic operation between the photographed image signal and a tap coefficient obtained by learning performed in advance; and display control means for causing display means to display the image corresponding to the high-quality image signal in a display format determined by learning performed using an image higher in quality than the image corresponding to the high-quality image signal.