The restoration of nonuniform distorted infrared (IR) images is crucial for human visual perception and subsequent application tasks. However, existing methods sometimes fail to yield visually natural decompositions and perform insufficiently in the preservation of meaningful structures while suppressing disturbing noise. A spatially adaptive hybrid ℓ1 − ℓ2 variational framework for the nonuniform intensity correction of IR images is proposed. Considering the piecewise constant characteristics of latent images, a weighted ℓ1-norm regularization method is developed to constrain the local affinity of neighborhood pixels according to their intensity and structural priors, thereby significantly preserving structures while smoothly flattening areas. Additionally, an ℓ2-norm guided local smoothness constraint is incorporated with an absolute scale term provided by coarse estimation to characterize the bias field component to restrict potential solutions and enforce the bias component to be textureless. Moreover, the proposed ℓ1 − ℓ2 model is efficiently solved by an alternating direction method of multipliers scheme. Extensive experiments on both synthesized images and two real-world IR datasets indicate that the performance of the proposed method is superior to that of five existing algorithms both visually and numerically.
The detection of pavement cracks is essential for damage assessment and maintenance of pavement. Obtaining complete crack paths using traditional approaches is difficult due to the varied appearance of pavement cracks and complex texture noise. A robust graph network refining algorithm guided by multiscale curvilinear structure filtering (CFGNR) is proposed for pavement crack detection. A multiscale curvilinear structure filter consisting of curved linear templates and a local texture inhibition term is first utilized to enhance crack contours. The enhanced pavement image is then presented as a graph of overcomplete crack paths, and a graph network refining approach derived from path saliency and local contrast constraints is utilized to select the optimal subset of crack paths. Finally, an iterative path growing algorithm is employed to obtain pixel-level cracks. Experimental results on four public pavement datasets show that the proposed algorithm significantly improves the completeness of detected cracks and achieves a superior performance compared to six existing algorithms.
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