High-Frequency Injected Transformer for Effective Image Restoration

Core Concepts

The core message of this paper is to propose a Transformer-based model, called HIT, that effectively leverages high-frequency information to enhance image restoration performance while maintaining the large receptive field benefit of Transformers.

Abstract

The paper presents a new Transformer-based model called HIT (High-frequency Injected Transformer) for image restoration tasks. The key contributions are:

HIT utilizes a CNN-based extractor to capture fine high-frequency details, while ensuring the Transformer focuses on modeling global context. This design enhances high-frequency information while maintaining the large receptive field benefit of the Transformer.

HIT introduces a window-wise injection module (WIM) to integrate high-frequency information into separate windows of the feature map. To prevent the high-frequency details from being diluted by the low-pass filter-like self-attention mechanism, HIT develops a bidirectional interaction module (BIM) to achieve spatially and semantically improved representations, and a spatial enhancement unit (SEU) to preserve crucial spatial details.

Extensive experiments on 9 image restoration tasks, including denoising, deraining, deblurring, demoiréing, deshadowing, desnowing, dehazing, and low-light enhancement, demonstrate the effectiveness of HIT compared to state-of-the-art methods.

Stats

The proposed HIT model achieves a PSNR of 39.94 dB on the SIDD denoising dataset, outperforming the previous best method DIL by 0.97 dB.
On the SPAD deraining dataset, HIT-B obtains a PSNR of 49.16 dB, surpassing the previous best method DRSformer by 0.63 dB.
For low-light image enhancement on the SMID dataset, HIT-B achieves a PSNR of 29.37 dB, outperforming the previous best Retinexformer by 0.22 dB.
On the RealBlur deblurring benchmark, HIT-B surpasses the recent method FFTformer by 2.75 dB in PSNR.

Quotes

"The key idea of our HIT is High-frequency Injection in Transformer with the proposed window-wise injection module (WIM)."
"Towards preventing most useful high-frequency information from being diluted by the subsequent repeated self-attention mechanism, which serves as a low-pass filter, we tailor two schemes."

Key Insights Distilled From

Look-Around Before You Leap

by Shihao Zhou,... at arxiv.org 04-02-2024

https://arxiv.org/pdf/2404.00279.pdf

Deeper Inquiries

How can the proposed high-frequency injection and bidirectional interaction modules be extended to other Transformer-based architectures for broader applications beyond image restoration

The proposed high-frequency injection and bidirectional interaction modules in the HIT model can be extended to other Transformer-based architectures for a variety of applications beyond image restoration. One way to extend these modules is to apply them to tasks such as video processing, where capturing both local details and global context is crucial. For example, in video denoising or deblurring, the high-frequency injection module can help preserve fine details in each frame, while the bidirectional interaction module can facilitate the aggregation of features across frames to enhance temporal coherence and consistency. Additionally, these modules can be adapted for tasks like image segmentation, where maintaining high-frequency information can improve boundary delineation and object recognition.

What are the potential limitations of the current HIT design, and how can it be further improved to handle more challenging real-world degradations

While the HIT model shows promising results in image restoration tasks, there are potential limitations that can be addressed for further improvement. One limitation is the computational complexity of the model, which can be a bottleneck for real-time applications or deployment on resource-constrained devices. To address this, optimization techniques such as model pruning, quantization, or distillation can be explored to reduce the model size and inference time without compromising performance. Additionally, enhancing the robustness of the model to handle more diverse and challenging real-world degradations, such as complex motion blur or mixed artifacts, can be achieved by incorporating more diverse training data and augmentations. Furthermore, exploring self-supervised or unsupervised learning strategies can help the model generalize better to unseen degradation types and scenarios.

Given the effectiveness of leveraging high-frequency information, are there any insights that can be drawn for the general design of Transformer-based models to better capture both local and global features

The success of leveraging high-frequency information in the HIT model provides valuable insights for the general design of Transformer-based models to better capture both local and global features. One key insight is the importance of incorporating task-specific modules, such as the high-frequency injection module, to address the limitations of Transformers in capturing fine details. By designing modules that focus on different aspects of the input data, such as local patterns and long-range dependencies, Transformer-based models can achieve a more comprehensive understanding of the input and produce more accurate results. Additionally, the bidirectional interaction module highlights the significance of feature aggregation across different scales, enabling the model to learn from diverse perspectives and enhance the representation of the input data. Overall, these insights can guide the development of more effective and versatile Transformer architectures for a wide range of applications in computer vision and beyond.