Gradient-Based Correction of Chromatic Aberration in the Joint Acquisition of Color and Near-Infrared Images

Chromatic aberration distortions, such as wavelength-dependent blur caused by imperfections in photographic lenses, have long been studied in color imaging. The problem becomes more challenging to solve in the case of color and near-infrared joint acquisition, as a wider range of wavelengths is captured. In this paper, we assume that the color image is in focus, hence, the NIR image captured with the same focus settings is blurred. We propose an algorithm that estimates the blur kernel and deblurs the NIR image, using the in-focus color image as a guide in both steps. In the deblurring step, we retrieve the lost details of the NIR image by using the sharp edges of the color image. The main diculty in this task is caused by the fact that the edges of color and NIR images are not always correlated. To handle this issue, the algorithm analyzes the dierences between the gradients of NIR and color channels. Simulation results verify the eectiveness of our algorithm, both in estimating the blur kernel and deblurring the NIR image, without producing ringing artifacts inherent to the results of other deblurring methods

Mapping and Deep Analysis of Image Dehazing: Coherent Taxonomy, Datasets, Open Challenges, Motivations, and Recommendations

Our study aims to review and analyze the most relevant studies in the image dehazing field. Many aspects have been deemed necessary to provide a broad understanding of various studies that have been examined through surveying the existing literature. These aspects are as follows: datasets that have been used in the literature, challenges that other researchers have faced, motivations, and recommendations for diminishing the obstacles in the reported literature. A systematic protocol is employed to search all relevant articles on image dehazing, with variations in keywords, in addition to searching for evaluation and benchmark studies. The search process is established on three online databases, namely, IEEE Xplore, Web of Science (WOS), and ScienceDirect (SD), from 2008 to 2021. These indices are selected because they are sufficient in terms of coverage. Along with definition of the inclusion and exclusion criteria, we include 152 articles to the final set. A total of 55 out of 152 articles focused on various studies that conducted image dehazing, and 13 out 152 studies covered most of the review papers based on scenarios and general overviews. Finally, most of the included articles centered on the development of image dehazing algorithms based on real-time scenario (84/152) articles. Image dehazing removes unwanted visual effects and is often considered an image enhancement technique, which requires a fully automated algorithm to work under real-time outdoor applications, a reliable evaluation method, and datasets based on different weather conditions. Many relevant studies have been conducted to meet these critical requirements. We conducted objective image quality assessment experimental comparison of various image dehazing algorithms. In conclusions unlike other review papers, our study distinctly reflects different observations on image dehazing areas. We believe that the result of this study can serve as a useful guideline for practitioners who are looking for a comprehensive view on image dehazing

NEW TECHNIQUES IN DERIVATIVE DOMAIN IMAGE FUSION AND THEIR APPLICATIONS

There are many applications where multiple images are fused to form a single summary greyscale or colour output, including computational photography (e.g. RGB-NIR), diffusion tensor imaging (medical), and remote sensing. Often, and intuitively, image fusion is carried out in the derivative domain (based on image gradients). In this thesis, we propose new derivative domain image fusion methods and metrics, and carry out experiments on a range of image fusion applications. After reviewing previous relevant methods in derivative domain image fusion, we make several new contributions. We present new applications for the Spectral Edge image fusion method, in thermal image fusion (using a FLIR smartphone accessory) and near-infrared image fusion (using an integrated visible and near-infrared sensor). We propose extensions of standard objective image fusion quality metrics for M to N channel image fusion measuring image fusion performance is an unsolved problem. Finally, and most importantly, we propose new methods in image fusion, which give improved results compared to previous methods (based on metric and subjective comparisons): we propose an iterative extension to the Spectral Edge image fusion method, producing improved detail transfer and colour vividness, and we propose a new derivative domain image fusion method, based on finding a local linear combination of input images to produce an output image with optimum gradient detail, without artefacts - this mapping can be calculated by finding the principal characteristic vector of the outer product of the Jacobian matrix of image derivatives, or by solving a least-squares regression (with regularization) to the target gradients calculated by the Spectral Edge theorem. We then use our new image fusion method on a range of image fusion applications, producing state of the art image fusion results with the potential for real-time performance

Semantic Image Segmentation Using Visible and Near-Infrared Channels

Recent progress in computational photography has shown that we can acquire physical information beyond visible (RGB) image representations. In particular, we can acquire near-infrared (NIR) cues with only slight modification to any standard digital camera. In this paper, we study whether this extra channel can improve semantic image segmentation. Based on a state-of-the-art segmentation framework and a novel manually segmented image database that contains 4-channel images (RGB+NIR), we study how to best incorporate the specific characteristics of the NIR response. We show that it leads to improved performances for 7 classes out of 10 in the proposed dataset and discuss the results with respect to the physical properties of the NIR response