Onni primarily works with the collage technique —better known in the field as composite photography— where multiple images are combined into a single seamless composition. Sometimes this may involve just a few photographs, while other pieces can require hundreds.

Lighting and perspective are at the heart of creating believable compositions. Because he manages the entire process himself —from concept and photography to post-production— he maintains full creative control over the final result.

In his personal projects, Onni never uses computer-generated imagery (such as 3D or AI) or stock photos. Every element comes from his own photographs, combined into complex and imaginative new realities.