PICS: Pairwise Image Compositing with Spatial Interactions

Hang Zhou1  Xinxin Zuo2  Sen Wang2  Li Cheng1
University of Alberta  Concordia University
ICLR26
arXiv Code

Our method generates spatially plausible and visually realistic pairwise compositions. Each row illustrates two examples, consisting of (from left to right) the objects, the masked background, and two exemplar composite results.

Visual comparison of pairwise support relations across Paint-by-Paint, ControlCom, ObjectStitch, AnyDoor, FreeCompose, OmniPaint, and InsertAnything. Left: backgrounds and two objects; right: compositing results. The first row shows composites with the basket, and the second row shows subsequent composites obtained by adding the bread on top. Unlike prior methods that suffer from contact artifacts and fidelity loss, our approach performs parallel compositing and yields consistent results with preserved structure.

Abstract

Despite strong single-turn performance, diffusion-based image compositing often struggles to preserve coherent spatial relations in pairwise or sequential edits, where subsequent insertions may overwrite previously generated content and disrupt physical consistency. We introduce PICS, a self-supervised composition-by-decomposition paradigm that composes objects in parallel while explicitly modeling the compositional interactions among (fully-/partially-)visible objects and background. At its core, an Interaction Transformer employs mask-guided Mixture-of-Experts to route background, exclusive, and overlap regions to dedicated experts, with an adaptive $\alpha$-blending strategy that infers a compatibility-aware fusion of overlapping objects while preserving boundary fidelity. To further enhance robustness to geometric variations, we incorporate geometry-aware augmentations covering both out-of-plane and in-plane pose changes of objects. Our method delivers superior pairwise compositing quality and substantially improved stability, with extensive evaluations across virtual try-on, indoor, and street scene settings showing consistent gains over state-of-the-art baselines.

Method

Overview of PICS. Input data are constructed by decomposing the target image into a background and pairwise objects with their designated regions. (a) The interaction diffusion network composites the objects into the background. (b) The interaction transformer block, shared across both branches, models interactions among objects and with the background. (c) Expert blocks focus on distinct spatial regions. All notations are defined in the main text for clarity.