RotBench: Evaluating Multimodal Large Language Models on Identifying
  Image Rotation
Authors: name: Tianyi Niu, name: Jaemin Cho, name: Elias Stengel-Eskin, name: Mohit Bansal

We investigate to what extent Multimodal Large Language Models (MLLMs) can
accurately identify the orientation of input images rotated 0{\deg}, 90{\deg},
180{\deg}, and 270{\deg}. This task demands robust visual reasoning
capabilities to detect rotational cues and contextualize spatial relationships
within images, regardless of their orientation. To evaluate MLLMs on these
abilities, we introduce RotBench -- a 350-image manually-filtered benchmark
comprising lifestyle, portrait, and landscape images. Despite the relatively
simple nature of this task, we show that several state-of-the-art open and
proprietary MLLMs, including GPT-5, o3, and Gemini-2.5-Pro, do not reliably
identify rotation in input images. Providing models with auxiliary information
-- including captions, depth maps, and more -- or using chain-of-thought
prompting offers only small and inconsistent improvements. Our results indicate
that most models are able to reliably identify right-side-up (0{\deg}) images,
while certain models are able to identify upside-down (180{\deg}) images. None
can reliably distinguish between 90{\deg} and 270{\deg}. Simultaneously showing
the image rotated in different orientations leads to moderate performance gains
for reasoning models, while a modified setup using voting improves the
performance of weaker models. We further show that fine-tuning does not improve
models' ability to distinguish 90{\deg} and 270{\deg} rotations, despite
substantially improving the identification of 180{\deg} images. Together, these
results reveal a significant gap between MLLMs' spatial reasoning capabilities
and human perception in identifying rotation.