Learn from orientation prior for radiograph super-resolution: Orientation operator transformer

Abstract

Background and objective: High-resolution radiographic images play a pivotal role in the early diagnosis and treatment of skeletal muscle-related diseases. It is promising to enhance image quality by introducing single-image super-resolution (SISR) model into the radiology image field. However, the conventional image pipeline, which can learn a mixed mapping between SR and denoising from the color space and inter-pixel patterns, poses a particular challenge for radiographic images with limited pattern features. To address this issue, this paper introduces a novel approach: Orientation Operator Transformer - O²former.

Methods: We incorporate an orientation operator in the encoder to enhance sensitivity to denoising mapping and to integrate orientation prior. Furthermore, we propose a multi-scale feature fusion strategy to amalgamate features captured by different receptive fields with the directional prior, thereby providing a more effective latent representation for the decoder. Based on these innovative components, we propose a transformer-based SISR model, i.e., O²former, specifically designed for radiographic images.

Results: The experimental results demonstrate that our method achieves the best or second-best performance in the objective metrics compared with the competitors at ×4 upsampling factor. For qualitative, more objective details are observed to be recovered.

Conclusions: In this study, we propose a novel framework called O²former for radiological image super-resolution tasks, which improves the reconstruction model's performance by introducing an orientation operator and multi-scale feature fusion strategy. Our approach is promising to further promote the radiographic image enhancement field.

Keywords: Feature fusion; Orientation feature; Radiographs; Super-resolution.