Adding photographic grain via Camera Raw Filter's Effects panel (Amount, Size, Roughness) on a final merged/stamped layer, to visually unify a sharp real subject with a smoother AI-generated background.
Increasing grain size in Camera Raw also introduces a slight accompanying blur — normally a side effect, but treated here as desirable because that's how grain behaves in old/vintage photos. The "flaw" of blur-from-grain becomes a naturalizing texture match between the sharp subject and the smoother AI content, rather than something to avoid.
Final step of Generative Fill Background Compositing Workflow, applied after color grading (Post-Generative-Fill Color Grading Stack (Light Flare + LUT + Clipped Curves)) and blur (Tilt-Shift Blur to Mask Low-Resolution AI Backgrounds).
Generative Fill Background Compositing Workflow, Tilt-Shift Blur to Mask Low-Resolution AI Backgrounds
This finishing step is not AI-specific: fully manual (zero-AI) composite courses teach the identical practice as a mandatory last pass. PHLEARN's remade panorama-compositing course explicitly matches resolution and grain across every layer of a dozens-of-photographs composite so the final image "looks like it was shot on one camera" — the same rationale used for grain-matching AI-generated composite layers, applied to a hand-built one. See Depth-Ordered Compositing Workflow (Background-to-Foreground Build Sequence) for the full build sequence this closes out.