Delving into RL for Image Generation with CoT: A Study on DPO vs. GRPO - Tong, Chengzhuo; Guo, Ziyu; Zhang, Renrui; Shan, Wenyu; Wei, Xinyu; Xing, Zhenghao; Li, Hongsheng; Heng, Pheng-Ann (Advances in Neural Information Processing Systems, 2025)