Authors: Yijiang Li, Yijun Liang, Yunjie Tian, Bingyang Wang, Ke Zhang, Zhenfei Yin, Di Fu, Philip Torr, Nuno Vasconcelos
Organizations: UC San Diego · University of Maryland, College Park · Independent Researcher · Georgia Institute of Technology · Johns Hopkins University · University of Oxford
Visual on-policy distillation relies heavily on an informative teacher-student asymmetry, through either a larger, stronger teacher or privileged supervision, such as reference answers or ground-truth regions of interest. This raises a fundamental question: where can informative asymmetry come from when nothing privileged is available? We answer this by inverting where the asymmetry comes from. Rather than adding privileged information to the teacher, we subtract information from the student. This asymmetry creates the same effective learning signal for free as a teacher with access to information unavailable to the student, without ground-truth annotations, rewards, or a separate stronger teacher model. Building on this principle, we introduce Self-Supervised Visual On-Policy Distillation (S2VOPD), a simple yet effective method that constructs on-policy learning signals from asymmetric augmented views. S2VOPD distills the teacher's distribution conditioned on the original image on-policy into the student distribution conditioned on a strongly augmented view of the same image. We systematically explore a broad design space of visual augmentations and uncover that (1) asymmetry matters: all four augmentation families improve performance, while symmetric self-distillation degrades it; (2) strength matters: performance peaks at a moderate strength; and (3) the gap must remain task-consistent: augmentations that completely remove the question-relevant evidence can induce large but uninformative discrepancies. Across six fine-grained perception benchmarks, S2VOPD improves Qwen3.5-4B from 70.7% to 77.4%, above all open-source models compared, up to Qwen3-VL at 235B, and surpasses GPT-5.4. While holding training data the same, it recovers 96% of the improvement achieved by methods with privileged information. Website is at https://williamium3000.github.io/s2vopd
Figures & tables
Figure 1: Overview of S 2 VOPD. The student generates rollouts from a corrupted view of the image; an EMA teacher scores the same generated prefixes under the clean view; a top- k generalized JSD transfers the teacher’s better-informed token distributions to the student. The augmentation applied to the student view is the sole source of supervision and the object of our study.
Operator
Effects
Strengths Range
Information reduction
Downscale
fewer pixels and visual tokens (no resize-back)
s∼U(0.3,0.6) ; 0.4 – 0.7 ; 0.25 – 0.5
Downscale, 3-tier
one of three bands drawn per sample
[0.2,0.35] , [0.35,0.5] , [0.5,0.75]
Gaussian blur
soft low-pass
radius U(0.5,1.5) ; (1.5,3.0) ; (3.0,6.0)
Spectral band-stop
removes an annulus of the 2D spectrum
inner radius 0.15 – 0.35 , width 0.15 – 0.3
Gaussian noise
additive; lowers signal-to-noise ratio
DDPM step 200 ( σ≈0.11 ), ρ=0.5
Table 1: Overview of augmentation operators on the student policy.
Method
Size
V*
Zoom
HR-4K
HR-8K
MME-RW
MME-RW-CN
Avg
Open-source models
MiniCPM-V-4.5
–
70.68
42.60
69.63
61.50
62.65
61.64
61.45
Qwen2.5-VL
7B
78.53
42.49
71.62
67.88
60.80
58.30
63.27
MiMo-VL-RL
7B
83.25
45.68
73.50
69.38
62.73
55.89
65.07
Qwen3-VL
4B
80.10
40.24
78.25
72.88
63.47
63.63
66.43
Thyme
7B
82.20
45.09
77.00
72.00
64.80
64.59
67.61
Table 2: Performance of S 2 VOPD trained on a 12k subset of FineVision ( Wiedmann et al., 2026 ) , compared with open-source, proprietary, and methods that use privileged information on fine-grained perception benchmarks (accuracy, %; Avg is the average over the 6 benchmarks).
Perception
Math reasoning
Method
V*
Zoom
HR-4K
HR-8K
MME-RW
MME-RW-CN
MathVista
MathVerse
MathVision
Avg
Qwen3.5-4B
Qwen3.5-4B
84.29
47.69
84.38
80.13
63.86
63.70
75.80
67.56
65.26
70.30
w/ privileged info.
ZwZ-4B ( Wei et al., 2026 )
92.67
55.74
81.75
79.50
68.52
68.09
71.80
40.48
52.17
67.86
Opsd ( Zhao et al., 2026a )
85.86
59.88
84.25
76.75
74.70
73.40
72.80
66.17
55.92
72.19
Table 3: Comparison with prior methods trained on the Vision-OPD training data, across six fine-grained perception and three mathematical-reasoning benchmarks at different model scales. Bold and underline mark the best and the second-best entry in each column within each base model; § indicates that best instead of last checkpoint performance is reported.
Figure 2: (a) Performance of each augmentation family applied alone; (b) Accuracy vs. the teacher–student predictive gap induced by the augmentation. We measure the teacher-student gap as the token-level JS Divergence between the teacher and the student distributions, averaged over the first ten steps of training.
Method
V*
Zoom
HR-4K
HR-8K
MME-RW
MME-RW-CN
Avg
S 2 VOPD
87.43
57.99
84.88
83.62
72.87
71.29
76.35
w/o Aug.
79.06
50.18
86.50
80.62
62.85
63.90
70.52
w/o EMA (fixed teacher)
88.48
54.08
86.75
83.25
72.15
70.98
75.95
Table 4: Component ablation on S 2 VOPD-4B. w/o aug removes the view asymmetry by showing the student the same clean image as the teacher; w/o EMA keeps the augmentation but freezes the teacher at the base model.