Recognizing Instagram Filtered Images with Feature De-stylization

TL;DR

This paper investigates how Instagram filters affect pretrained neural networks and introduces a lightweight de-stylization module that improves model robustness against such filters by normalizing feature space alterations.

Contribution

The paper presents a novel lightweight de-stylization module that can be integrated into CNNs to counteract the effects of Instagram filters, enhancing robustness without full retraining.

Findings

Filters cause significant feature space shifts in CNNs.

The de-stylization module improves generalization on filtered images.

Normalization parameters can be learned without retraining the entire network.

Abstract

Deep neural networks have been shown to suffer from poor generalization when small perturbations are added (like Gaussian noise), yet little work has been done to evaluate their robustness to more natural image transformations like photo filters. This paper presents a study on how popular pretrained models are affected by commonly used Instagram filters. To this end, we introduce ImageNet-Instagram, a filtered version of ImageNet, where 20 popular Instagram filters are applied to each image in ImageNet. Our analysis suggests that simple structure preserving filters which only alter the global appearance of an image can lead to large differences in the convolutional feature space. To improve generalization, we introduce a lightweight de-stylization module that predicts parameters used for scaling and shifting feature maps to "undo" the changes incurred by filters, inverting the process of style transfer tasks. We further demonstrate the module can be readily plugged into modern CNN architectures together with skip connections. We conduct extensive studies on ImageNet-Instagram, and show quantitatively and qualitatively, that the proposed module, among other things, can effectively improve generalization by simply learning normalization parameters without retraining the entire network, thus recovering the alterations in the feature space caused by the filters.