Subjective assessment for inverse rendered composite images in 360-deg images

Abstract

Due to the rise of social media, synthesized or composited photos are becoming increasingly widespread, and image relighting is one of the crucial technologies that is capable of creating convincingly realistic images. Our study proposes a framework for relighting a portrait subject when superimposing it onto a 360-deg image. In most image compositions, it is difficult to acquire the 3D shapes of subjects directly to rerender them in a virtual environment. A well-diffused color portrait image with a corresponding normal map is generated from our photo booth using a photometric method. In addition, a virtual environment based on a principled bidirectional scattering distribution shader and environmental 360-deg texture in the Blender software is utilized to create composite images. After considering different situations, including gender, postures, indoor or outdoor scenes, and color or color-free subjects, each of 128 composite images was played as a 4-s video clip, and various scenarios were conducted for subjective assessment. From the evaluation scores of the 30 participants, the overall satisfaction with the image composition based on the proposed framework was above average (5-point Likert scale > 3 points), and the color-free subject in the 360-deg image was significantly preferred.