1. Introduction
With the development of information and communication technologies, the use of the Internet and smartphone devices has become common in modern society. Accordingly, consumers can easily and quickly obtain the information they want without restrictions in time and space. In particular, image-based social network services such as Instagram and Pinterest can compress various moments of everyday life through image information. Such visual information is relatively faster and easier to share than written information. Especially, unlike photos that show objects as they are, photos with controlled light, depth, and white balance can effectively convey users' opinions, ideas, emotion, mood, etc. Recently, attempts have been made to implement photo effects using deep learning to make it easier for users to capture their intentions with smartphones instead of highend professional cameras. Among them, bokeh effect rendering is a relatively new research problem that has emerged over the past few years.