Introducing Resizable Region Packing Problem in Image Generation, with a Heuristic Solution

Abstract

The problem of image data generation in computer vision has traditionally been a harder problem to solve, than discriminative problems. Such data generation entails placing relevant objects of appropriate sizes each, at meaningful location in a scene canvas. There have been two classes of popular approaches to such generation: graphics based, and generative models-based. Optimization problems are known to lurk in the background for both these classes of approaches. In this paper, we introduce a novel, practically useful manifestation of the classical Bin Packing problem in the context of generation of synthetic image data. We conjecture that the newly introduced problem, Resizable Anchored Region Packing(RARP) Problem, is NP-hard, and provide detailed arguments about our conjecture. As a first solution, we present a novel heuristic algorithm that is generic enough and therefore scales and packs arbitrary number of arbitrary-shaped regions at arbitrary locations, into an image canvas. The algorithm follows greedy approach to iteratively pack region pairs in a careful way, while obeying the optimization constraints. The algorithm is validated by an implementation that was used to generate a large-scale synthetic anomaly detection dataset, with highly varying degree of bin packing parameters per image sample i.e. RARP instance. Visual inspection of such data and checking of the correctness of each solution proves the effectiveness of our algorithm. With generative modeling being on rise in deep learning, and synthetic data generation poised to become mainstream, we expect that the newly introduced problem will be valued in the imaging scientific community.