The Shape of Events: Edge-Based Inductive Biases via Cross-Domain Distillation
Organizations: Independent Researcher · The University of Tokyo, Japan · Graduate School of Artificial Intelligence and Science, Rikkyo University, Japan · RIKEN, Japan
Abstract
Convolutional neural networks trained on ImageNet are known to exhibit a strong preference for local high-frequency texture, an inductive bias that translates into fragile robustness against distribution shifts in real-world environments. Event cameras, in contrast, record only changes in scene brightness and are therefore well suited to capturing contour information; however, due to the absence of diagnostic benchmarks in the event domain, the inductive bias that event-camera data instills in vision models has remained underexplored. In this work, we use knowledge distillation from the event domain to the RGB domain so as to exploit the rich evaluation toolkit available in the RGB domain and systematically dissect this inductive bias. Our experiments show that distillation from the event domain induces, in the RGB domain, color invariance, shape bias, and robustness to high-frequency noise. We identify the underlying mechanism as the model suppressing its dependence on high-frequency texture while acquiring a stronger dependence on edge-based object shape. This hypothesis is supported by changes in how color and spatial information are processed at the early layers, together with a spectral trade-off in which robustness to the absence of high-frequency components coexists with vulnerability to contamination of the relied-upon frequency bands and to disruption of geometric structure. We further show that this inductive bias differs from existing robustification methods and that it functions as a useful prior for diverse downstream tasks in which shape and contour information contribute alongside other cues. The code is available at https://github.com/snskysk/event2rgb-distillation .
Figures & tables
| C100 | C10 | ChXR | MNIST | Cars | DTD | STL10 | INet-sk | Cal101 | INet-v2 | Scene | SUN397 | Flwr | KITTI | ESAT | CUB | PCam | Pet | Food | Mean | INet | |
| base. (%) | 55.8 | 78.0 | 87.3 | 89.9 | 46.9 | 60.1 | 94.8 | 62.2 | 85.4 | 49.6 | 90.6 | 53.5 | 85.3 | 73.4 | 90.0 | 64.6 | 78.0 | 90.5 | 61.4 | 73.5 | 73.9 |
| ED ( ) | 5.2 | 4.8 | 4.3 | 3.4 | 2.3 | 1.9 | 1.8 | 1.4 | 1.2 | 0.9 | 0.8 | 0.8 | 0.7 | 0.7 | 0.4 | 0.3 | 0.2 | 0.1 | 0.4 | 1.6 | 4.2 |
| Adv. ( ) | 14.6 | 10.8 | 2.9 | 5.6 | 8.7 | 9.1 | 0.7 | 5.2 | 0.4 | 12.3 | 0.5 | 7.8 | 9.4 | 2.1 | 1.2 | 3.4 | 0.0 | 3.2 | 9.5 | 1.8 | 7.9 |
| Noise ( ) | 3.2 | 2.6 | 0.6 | 0.7 | 5.6 | 2.5 | 0.6 | 4.5 | 0.7 | 1.7 | 0.8 | 2.3 | 3.9 | 0.4 | 1.7 | 0.2 | 0.3 | 0.1 | 3.8 | 0.8 | 0.5 |
| SIN ( ) | 6.2 | 5.6 | 0.0 | 1.8 | 8.3 | 4.2 | 1.4 | 4.5 | 0.7 | 4.1 | 0.3 | 1.9 | 5.5 | 3.2 | 2.2 | 3.0 | 1.2 | 0.6 | 1.1 | 0.9 | 1.7 |
| Canny ( ) | 1.8 | 1.0 | 0.2 | 0.3 | 1.1 | 1.4 | 0.9 | 1.5 | 0.1 | 2.9 | 0.2 | 0.2 | 0.1 | 0.1 | 1.7 | 2.1 | 0.3 | 0.1 | 0.7 | 0.2 | 2.8 |
| Clean | Color (hue Avg.) | Shape (sketch) | High-freq (bandpass) | Transfer (LP Avg.) | Axes improved | |
|---|---|---|---|---|---|---|
| baseline (abs.) | 73.9 | 61.8 | 23.7 | 29.6 | 73.5 | — |
| ED_Student | 69.7 | 4 / 4 | ||||
| Canny_Distilled | 71.1 | 3 / 4 | ||||
| Synth_Distilled | 71.8 | 1 / 4 | ||||
| Adv. Training | 66.0 | 1 / 4 | ||||
| Noise Training | 74.4 | 3 / 4 |
Appendix figures & tables27 assets
Supplementary material from the paper’s appendix.
Appendix
| Item | Value |
|---|---|
| Input representation | DiST ( reshape_then_acc_adj_sort ), 2 ch, |
| Event slicing | Random, slice_length |
| Batch size | 512 |
| Weight decay | |
| Momentum | 0.9 |
| Epochs | 100 |
| Architecture | Optimizer | Learning rate | First-conv kernel size |
|---|---|---|---|
| ResNet-50 | Adam | 14 | |
| VGG16-BN | Adam | 14 | |
| ConvNeXt-Base | AdamW | 4 | |
| RepLKNet31B | AdamW | 4 |
| Model | Teacher | |
|---|---|---|
| baseline | 0.0 | – |
| ED_Student (main) | 0.2 | DiST ResNet-34 |
| ED_SoftLabelOnly | 1.0 | DiST ResNet-34 |
| Self Distilled | 0.2 | RGB ResNet-34 baseline |
| Gray Distilled | 0.2 | Grayscale ResNet-34 |
| B&W Distilled | 0.2 | B&W ResNet-34 |
| Model | LR | Weight decay | Epochs | LR schedule |
|---|---|---|---|---|
| baseline / ED_Student / ED_SoftLabelOnly | 120 | 5-epoch linear warmup cosine | ||
| Self / Gray / B&W Distilled | 120 | 5-epoch linear warmup cosine | ||
| SIN | 120 | 5-epoch linear warmup cosine | ||
| Adversarial Training | 50 | Cosine annealing (no warmup) | ||
| Noise Training | 120 | Cosine annealing (no warmup) |
| Operation | Setting |
|---|---|
| RandomResizedCrop | output , scale |
| RandomHorizontalFlip | |
| RandAugment | num_ops , magnitude |
| Normalize | ImageNet mean/std |
| RandomErasing |
| Operation | Setting |
|---|---|
| Resize | 256 |
| CenterCrop | 224 |
| Normalize | ImageNet mean/std |
| Operation | Setting |
|---|---|
| RandomResizedCrop | output , scale , NEAREST interpolation |
| RandomHorizontalFlip | |
| Normalize | ImageNet mean/std |
| Teacher | Student (ImageNet) | |||
|---|---|---|---|---|
| Architecture | DiST | ED_SoftLabelOnly | ED_Student | baseline |
| ResNet-34 | 48.43 | 53.50 | 69.70 | 73.90 |
| VGG16-BN | 42.13 | 24.14 | 55.90 | 69.01 |
| ConvNeXt-Base | 52.42 | 70.97 | 78.40 | 81.50 |
| ResNet-50 | 51.11 | 59.68 | 67.47 | 78.16 |
| RepLKNet31B | 51.61 | 67.43 | 76.61 | 83.45 |
| Control | Teacher input | Teacher | Student |
|---|---|---|---|
| Canny_Distilled | Canny edge map (3ch) | 55.82 | 71.15 |
| Synth_Distilled | augmentation-difference ON/OFF (2ch) | 64.52 | 71.78 |
| SOTA baseline | SOTA ED_Student | |
|---|---|---|
| Clean top-1 | 75.92 | 70.80 |
| ImageNet-Sketch top-1 | 26.98 | 28.94 |
| Hue rotation, mean over – | 63.96 | 65.76 |
| Patch shuffle, grid | 53.82 | 37.48 |
| Patch rotation, grid | 46.54 | 31.61 |
| FGSM, mean over | 34.74 | 28.70 |
| LP mean | Hue Avg. | Grayscale | Cue-conflict | Sketch | Bandpass @ | Adv. AUC | |
|---|---|---|---|---|---|---|---|
| baseline | 73.5 | 61.8 | 62.4 | 0.212 | 23.7 | 44.3 | 6.2 |
| ED_Student | 75.1 | 65.4 | 64.6 | 0.375 | 28.1 | 57.5 | 8.9 |
| ED_SoftLabelOnly | — | 52.4 | 52.6 | 0.487 | 24.5 | 45.8 | 9.1 |
| Canny_Distilled | 73.7 | 66.1 | 65.1 | 0.270 | 27.9 | 35.6 | 7.5 |
| Adversarial Training | 71.7 | 50.6 | 49.5 | 0.572 | 21.3 | 64.5 | 24.1 |
| Noise Training | 72.7 | 62.6 | 63.3 | 0.258 | 25.4 | 58.2 | 11.5 |
| ImageNet-val | grayscale | sketch | B&W | canny | silhouette | |
|---|---|---|---|---|---|---|
| baseline | 73.90 | 62.45 | 23.70 | 41.39 | 10.83 | 3.30 |
| ED_Student | 69.70 | 64.64 | 28.08 | 49.01 | 13.27 | 5.43 |
| ED_SoftLabelOnly | 53.50 | 52.58 | 24.47 | 34.87 | 11.45 | 5.42 |
| Self Distilled | 74.72 | 62.97 | 24.43 | 42.69 | 11.59 | 3.24 |
| Gray Distilled | 74.60 | 69.51 | 25.60 | 45.56 | 7.87 | 3.63 |
| B&W Distilled | 64.81 | 56.20 | 23.47 | 45.54 | 12.12 | 3.22 |
| Correlation Type | RGB Correlation | Spatial Autocorrelation |
|---|---|---|
| baseline | 0.549 | 0.391 |
| ED_Student | 0.544 | 0.398 |
| ED_SoftLabelOnly | 0.747 | 0.575 |
Event-Based Vision
Event-based vision uses asynchronous camera measurements to perceive motion and scene changes with high temporal resolution and dynamic range.
See all 236 papers