This book constitutes the refereed proceedings of the 38th Computer Graphics International Conference, CGI 2021, held virtually in September 2021. The 44 full papers presented together with 9 short papers were carefully reviewed and selected from 131 submissions. The papers are organized in the following topics: computer animation; computer vision; geometric computing; human poses and gestures; image processing; medical imaging; physics-based simulation; rendering and textures; robotics and vision; visual analytics; VR/AR; and engage.