  Different from universal object detection, referring expression comprehension
(REC) aims to locate specific objects referred to by natural language
expressions. The expression provides high-level concepts of relevant visual and
contextual patterns, which vary significantly with different expressions and
account for only a few of those encoded in the REC model. This leads us to a
question: do we really need the entire network with a fixed structure for
various referring expressions? Ideally, given an expression, only
expression-relevant components of the REC model are required. These components
should be small in number as each expression only contains very few visual and
contextual clues. This paper explores the adaptation between expressions and
REC models for dynamic inference. Concretely, we propose a neat yet efficient
framework named Language Adaptive Dynamic Subnets (LADS), which can extract
language-adaptive subnets from the REC model conditioned on the referring
expressions. By using the compact subnet, the inference can be more economical
and efficient. Extensive experiments on RefCOCO, RefCOCO+, RefCOCOg, and
Referit show that the proposed method achieves faster inference speed and
higher accuracy against state-of-the-art approaches.
