MoonDPO
Memory-Efficient DPO for Hallucination Mitigation in Small VLMs
Applies LoRA-based DPO to Moondream2 (1.9B) using preference pairs automatically generated from COCO annotations, without human or API labels. The DPO objective is derived and implemented from scratch, and the full pipeline is reproducible on a 16 GB laptop.
Preliminary (proof-of-concept run): CHAIRi 0.135 → 0.124, CHAIRs 0.215 → 0.200; POPE F1 essentially unchanged across splits. Caption length and objects-per-caption stay flat — the improvement is not from “saying less.” Single seed, small training budget; scaling data and running multiple seeds to establish the effect.
Research Setup
- Base model
- Moondream2 (1.9B)
- Adaptation
- LoRA + DPO
- Preference data
- COCO-derived pairs
- Compute
- 16 GB laptop
- Evaluation
- POPE + CHAIR