Pixel-Reasoner implements a two-stage training framework for Vision-Language Models (VLMs) to enable pixel-space reasoning. The system first performs instruction tuning on synthesized reasoning traces to familiarize models with visual operations (zoom-in, select-frame), then applies curiosity-driven reinforcement learning to balance exploration between pixel-space and textual reasoning. Targeting visual reasoning benchmarks (V* bench, TallyQA-Complex, InfographicsVQA, MVBench), it provides pre-trained models and evaluation scripts. The architecture combines adapted OpenRLHF components with custom VLM modules, Ray-based distributed training, and specialized data processors for multimodal input. Key entry points include training scripts (single/multi-node) and evaluation scripts, with data flowing from Hugging Face datasets through tokenization/image processing to PPO optimization loops.