Taming Generative Synthetic Data for X-ray Prohibited Item Detection

TL;DR

This paper introduces Xsyn, a one-stage text-to-image synthesis method for generating high-quality X-ray security images to improve prohibited item detection, reducing labor costs and outperforming previous approaches.

Contribution

Xsyn is the first one-stage synthesis pipeline that enhances X-ray image generation without extra labor, using cross-attention refinement and background occlusion modeling.

Findings

Xsyn achieves 1.2% higher mAP than previous methods.

Synthetic images improve detection performance across datasets.

The method reduces labor costs in data augmentation.

Abstract

Training prohibited item detection models requires a large amount of X-ray security images, but collecting and annotating these images is time-consuming and laborious. To address data insufficiency, X-ray security image synthesis methods composite images to scale up datasets. However, previous methods primarily follow a two-stage pipeline, where they implement labor-intensive foreground extraction in the first stage and then composite images in the second stage. Such a pipeline introduces inevitable extra labor cost and is not efficient. In this paper, we propose a one-stage X-ray security image synthesis pipeline (Xsyn) based on text-to-image generation, which incorporates two effective strategies to improve the usability of synthetic images. The Cross-Attention Refinement (CAR) strategy leverages the cross-attention map from the diffusion model to refine the bounding box annotation. The Background Occlusion Modeling (BOM) strategy explicitly models background occlusion in the latent space to enhance imaging complexity. To the best of our knowledge, compared with previous methods, Xsyn is the first to achieve high-quality X-ray security image synthesis without extra labor cost. Experiments demonstrate that our method outperforms all previous methods with 1.2% mAP improvement, and the synthetic images generated by our method are beneficial to improve prohibited item detection performance across various X-ray security datasets and detectors. Code is available at https://github.com/pILLOW-1/Xsyn/.