  Vision-language (VL) models often exhibit a limited understanding of complex
expressions of visual objects (e.g., attributes, shapes, and their relations),
given complex and diverse language queries. Traditional approaches attempt to
improve VL models using hard negative synthetic text, but their effectiveness
is limited. In this paper, we harness the exceptional compositional
understanding capabilities of generative foundational models. We introduce a
novel method for structured synthetic data generation aimed at enhancing the
compositional understanding of VL models in language-based object detection.
Our framework generates densely paired positive and negative triplets (image,
text descriptions, and bounding boxes) in both image and text domains. By
leveraging these synthetic triplets, we transform 'weaker' VL models into
'stronger' models in terms of compositional understanding, a process we call
"Weak-to-Strong Compositional Learning" (WSCL). To achieve this, we propose a
new compositional contrastive learning formulation that discovers semantics and
structures in complex descriptions from synthetic triplets. As a result, VL
models trained with our synthetic data generation exhibit a significant
performance boost in the Omnilabel benchmark by up to +5AP and the D3 benchmark
by +6.9AP upon existing baselines.
