Visual scale recognition is a fundamental aspect for humans to perceive physical quantities in the real world, and it is crucial for enabling human-like intelligence in multimodal large language models (MLLMs). However, existing benchmarks typically focus on a single type of quantity (e.g., time) or a specific format (e.g., dials), lacking a comprehensive evaluation of scale recognition capabilities. To address these problems, we propose ScaleBench, a visual scale recognition benchmark built using images from COCO, Open Images, and Flickr, designed to comprehensively evaluate the scale recognition capabilities of MLLMs. To ensure high data quality, we develop detailed annotation guidelines and procedures, resulting in a total of 6,574 annotated samples. Based on this benchmark, we evaluate multiple closed-source and open-source MLLMs. Experimental results reveal that the best-performing model achieves only 42.60% accuracy, far lower than the 97.40% of humans. Furthermore, we conduct in-depth experimental analyses and provide future research directions. Our benchmark and implementation codes are available at https://github.com/Sonder-hang/ScaleBench.

Medical visual question answering (MedVQA) requires models to provide accurate answers given a medical image and a corresponding question. Recently, instruction tuning of general large vision–language models (LVLMs) has become a dominant paradigm for this task, enabling open-ended predictions and effective integration of multimodal information. However, existing methods synthesize instruction data from image–caption pairs that primarily focus on visual attributes, rather than knowledge-level QA generation. This situation limits the model’s ability to learn relevant medical knowledge during training, thereby restricting its performance on MedVQA. Hence, this paper proposes MedKInstruct, which incorporates a multimodal medical knowledge graph (MMKG) to assist LVLMs in synthesizing knowledge-intensive instruction data. Additionally, we design an MMKG path–based reward function to train a stronger MedVQA model through reinforcement learning. Experimental results on the public datasets Slake and VQA-RAD show that MedKInstruct outperforms previous methods by 4.16% and 4.50%. The source code is available at the following link: https://github.com/Sonder-hang/MedKinstruct