Noise-Resistant Method Enables Edge Detection Without Prior Imaging

Edge detection, the process of outlining objects in a scene by identifying areas where changes in color or intensity signal boundaries between objects, is vital in computer vision applications such as object recognition, image segmentation, and feature extraction.

Traditionally, its accuracy depends on image quality. In visually noisy scenes, conventional methods aren’t effective. To tackle this challenge, a joint research team led by the Hefei University of Technology developed a noise-resistant method for detecting object edges without prior imaging.

The research, published in Intelligent Computing, presents a method called edge-sensitive single-pixel imaging. In scenarios where obtaining clear images through conventional optical methods is challenging due to factors such as severe light pollution, the new method proves effective in accurately detecting object edges despite the presence of noise.

To achieve this breakthrough, the researchers designed modulation patterns by convolving standard Hadamard single-pixel imaging patterns with second-order differential operators. This differential edge detection system significantly enhanced noise immunity, ensuring sharp and precise edge identification. Notably, the method exhibited real-time edge detection performance for moving objects, showcasing its potential for security checks in nonvisible bands.

A comparison of experimental results with different edge detection schemes. Courtesy of Mengchao Ma et al., https://spj.science.org/doi/10.34133/icomputing.0050.

The study also introduced a single-round derivative of the new method that reduces the number of modulation patterns required for edge detection, effectively halving the detection time. Despite this reduction, the method maintains a high signal-to-noise ratio and requires fewer modulation patterns compared to previously reported edge detection schemes.

Furthermore, the research team explored the new method in combination with the Laplacian and the Laplacian of Gaussian operators. Results indicated similar noise robustness, although using the former produced sharper edges, whereas using the latter yielded slightly coarser edges.

In rigorous comparisons, the new method outperformed existing schemes in terms of edge sharpness and signal-to-noise ratio. Additionally, under challenging experimental conditions with severe light pollution from a laser, both Laplacian variants surpassed standard imaging methods. The method delivered completely noise-free edge detection results, offering tremendous potential for practical applications.

The new method opens new possibilities for image processing by pre-coding modulation patterns to achieve direct results in an “image-free” manner. This eliminates the influence of noise, paving the way for incorporating other image processing procedures, such as homomorphic filtering, to further enhance results. The researchers envision optimizing the illumination patterns used in this work and exploring end-to-end optimization for future advancements.

The research was published in Intelligent Computing (www.doi.org/10.34133/icomputing.0050).