Glossary
ControlNet
Short answer
An extension binding generation to a reference image's pose, depth or edges.
ControlNet is the most powerful control tool in the Stable Diffusion ecosystem. It extracts structural information from a reference image — human pose, depth map, edge outlines — and fits the new generation onto that structure.
It makes possible what a prompt cannot express: showing the same product from exactly the same angle against different backgrounds, preserving a room's geometry while changing its style, generating a character in a specific pose.
This is the feature that makes Stable Diffusion indispensable in interior design, product photography and character work.
Example
Supply a photo of a room as a depth reference and run "the same room, Scandinavian minimalism" and the walls and windows stay in place while only materials and furniture change.