HiFi-Score: Fine-grained Image Description Evaluation with Hierarchical Parsing Graphs

With the advancements of vision-language models, the growing demand for generating customized image descriptions under length, target regions, and other various control conditions brings new challenges for evaluation. Most existing metrics, designed primarily for single-sentence image captioning with an overall matching score, struggle to accommodate complex description requirements, resulting in insufficient accuracy and interpretability of evaluation. Therefore, we propose HiFi-Score, a hierarchical parsing graph-based fine-grained evaluation metric. Specifically, we model both text and images as parsing graphs, which organize multi-granular instances into a hierarchical structure according to their inclusion relationships, which provides a comprehensive scene analysis for both modalities from global to local. Based on the fine-grained matching between the graphs, we can evaluate the fidelity to ensure text contents are related to image and the adequacy to ensure the image is covered by text at multiple levels. Furthermore, we employ the large language model to evaluate fluency of the language expression. Human correlation experiments on four caption-level benchmarks show that the proposed metric outperforms existing metrics. At the paragraph-level, we construct a novel dataset ParaEval and demonstrate the accuracy of the HiFi-Score in evaluating long texts. We further show its superiority in assessing vision-language models and its flexibility when applied to various image description tasks.