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VK Viekash,1 Janarthanam Jothi Balaji,2 Vasudevan Lakshminarayanan3 1Department of Instrumentation and Control Engineering, National Institute of Technology, Tiruchirappalli, Tamil Nadu, 620015, India; 2Department of Optometry, Medical Research Foundation, Chennai, Tamil Nadu, 600 006, India; 3Theoretical and Experimental Epistemology Lab, School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, N2L 3G1, CanadaCorrespondence: Janarthanam Jothi Balaji Tel +91 44-42271500Email jothibalaji@gmail.comIntroduction: Various ocular diseases and high myopia influence the anatomical reference point Foveal Avascular Zone (FAZ) dimensions. Therefore, it is important to segment and quantify the FAZs dimensions accurately. To the best of our knowledge, there is no automated tool or algorithms available to segment the FAZ’s deep retinal layer. The paper describes a new open-access software with a Graphical User Interface (GUI) and compares the results with the ground truth (manual segmentation).Methods: Ninety-three healthy normal subjects included 30 emmetropia and 63 myopic subjects without any sight-threatening retinal conditions, were included in the study. The 6mm x 6mm using the Angioplex protocol (Cirrus 5000 Carl Zeiss Meditec Inc., Dublin, CA) was used, and all the images were aligned with the centre of the fovea. Each FAZ image corresponding to dimensions 420× 420 pixels were used in this study. These FAZ image dimensions for the superficial and deep layers were quantified using the New Automated Software Method (NAM). The NAM-based FAZ dimensions were validated with the ground truth.Results: The age distribution for all 93 subjects was 28.02 ± 10.79 (range, 10.0– 66.0) years. For normal subjects mean ± SD age distribution was 32.13 ± 16.27 years. Similarly, the myopia age distribution was 26.06 ± 6.06 years. The NAM had an accuracy of 91.40%. Moreover, the NAM on superficial layer FAZ gave a Dice Similarity Coefficient (DSC) score of 0.94 and Structural Similarity Index Metric (SSIM) of 0.97, while the NAM on deep layer FAZ gave a DSC score of 0.96 and SSIM of 0.98.Conclusion: A clinician-based GUI software was designed and tested on the FAZ images from deep and superficial layers. The NAM outperformed the device’s inbuilt algorithm when measuring the superficial layer. This open-source software package is in the public domain and can be downloaded online.Keywords: image processing, foveal avascular zone, optical coherence tomography angiography, superficial retinal layer, deep retinal layer

Janarthanam Jothi Balaji,1 Vasudevan Lakshminarayanan2 1Department of Optometry, Medical Research Foundation, Chennai, Tamil Nadu, 600006, India; 2Theoretical and Experimental Epistemology Lab, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, N2L 3G1, CanadaCorrespondence: Janarthanam Jothi BalajiDepartment of Optometry, Medical Research Foundation, Chennai, Tamil Nadu, 600006, IndiaTel +91-44-4227-1500Fax +91-44-2825-4180Email jothibalaji@gmail.comIntroduction: Optic disc tilt (ODT) or tilted optic disc is a common finding in the general population. It is due to anomalous development caused by the malclosure of the embryonic optic fissure. ODT is commonly associated with high myopia as well as other conditions. In recent days, the common method to image the optic disc (OD) is by optical coherence tomography (OCT). To the best of our knowledge, there are no datasets of ODT available in the public domain. This dataset aims to make open access raw ODT OCT images to test out new image processing segmentation algorithms.Methods: This dataset of ODT images contains both horizontal and vertical cross-sectional images obtained using spectral-domain optical coherence tomography (SD-OCT, Cirrus 5000, Carl Zeiss Meditec Inc., Dublin, CA). The optic disc cube 200× 200 program was used and all the images are aligned with the center of the optic nerve head. This dataset includes images from both clinically normal (20 eyes) and myopic subjects (101 eyes).Results: The dataset consists of clear (121) and manually marked (121) images resulting in a total of 242 images. The age distribution for all subjects combined is 27.24 ± 9.28 (range, 11.0– 69.0) years. For normal subjects mean ± SD age distribution is 32.40 ± 17.23 years. Similarly, the myopia age distribution is 26.22 ± 6.37 years. Ground truth images, ie, manually segmented by a clinical expert are provided along with other meta-data includes age, gender, laterality, refractive error classification, spherical equivalent (SE), best-corrected visual acuity (BCVA), intraocular pressure (IOP), and axial length (AXL).Conclusion: This open, public database is online at the ICPSR website of the University of Michigan. The dataset can be used to test and validate newly developed automated segmentation algorithms.Keywords: optic disc tilt, high myopia, image segmentation, image database, ophthalmology, optical coherence tomography

Does life exist outside our Solar System? A first step towards searching for life outside our Solar System is detecting life on Earth by using remote sensing applications. One powerful and unambiguous biosignature is the circular polarization resulting from the homochirality of biotic molecules and systems. We aim to investigate the possibility of identifying and characterizing life on Earth by using airborne spectropolarimetric observations from a hot air balloon during our field campaign in Switzerland, May 2022. In this work we present the optical-setup and the data obtained from aerial circular spectropolarimetric measurements of farmland, forests, lakes and urban sites. We make use of the well-calibrated FlyPol instrument that measures the fractionally induced circular polarization ($V/I$) of (reflected) light with a sensitivity of $, 13 pages, 10 figures, to be submitted in SPIE Proceedings 12214-4

Asmaa Bakroon,1 Vasudevan Lakshminarayanan1–3 1Theoretical and Experimental Epistemology Laboratory, School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada; 2Departments of Physics and Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada; 3Department of Computer Engineering, University of Waterloo, Waterloo, ON, Canada Abstract: There is a rapid increase in the number of individuals with high-functioning autism (HFA). Research on motion perception in HFA has shown deficits in processing motion information at the higher visual cortical areas (V5/middle temporal). Several hypotheses have been put forth to explain these deficits as being due to enhanced processing of small details at the expense of the global picture or as a global integration abnormality. However, there is a lot of variability in the results obtained from experiments designed to study motion in adults with autism. These could be due to the inherent diagnostic differences within even the same range of the autism spectrum and/or due to comparison of different experimental paradigms whose processing by the same visual neural areas could be different. In this review, we discuss the various results on motion processing in HFA, as well as the theories of motion perception in autism. Keywords: autism-spectrum disorder, high-functioning autism, motion perception, biological motion, form perception, random-dot kinematogram, local motion, global motion&nbsp

Ahmed Almazroa,1,2 Weiwei Sun,3 Sami Alodhayb,4 Kaamran Raahemifar,5 Vasudevan Lakshminarayanan6 1King Abdullah International Medical Research Center (KAIMRC), Riyadh, Saudi Arabia; 2Ophthalmology and Visual Science Department, University of Michigan, Ann Arbor, MI, USA; 3School of Resource and Environmental Sciences, Wuhan University, Wuchang, Wuhan, Hubei, China; 4Bin Rushed Ophthalmic Center, Riyadh, Saudi Arabia; 5Department of Electrical and Computer Engineering, University of Ryerson, Toronto, ON, 6School of Optometry, University of Waterloo, ON, Canada Abstract: Segmenting the optic disc (OD) is an important and essential step in creating a frame of reference for diagnosing optic nerve head pathologies such as glaucoma. Therefore, a reliable OD segmentation technique is necessary for automatic screening of optic nerve head abnormalities. The main contribution of this paper is in presenting a novel OD segmentation algorithm based on applying a level set method on a localized OD image. To prevent the blood vessels from interfering with the level set process, an inpainting technique was applied. As well an important contribution was to involve the variations in opinions among the ophthalmologists in detecting the disc boundaries and diagnosing the glaucoma. Most of the previous studies were trained and tested based on only one opinion, which can be assumed to be biased for the ophthalmologist. In addition, the accuracy was calculated based on the number of images that coincided with the ophthalmologists’ agreed-upon images, and not only on the overlapping images as in previous studies. The ultimate goal of this project is to develop an automated image processing system for glaucoma screening. The disc algorithm is evaluated using a new retinal fundus image dataset called RIGA (retinal images for glaucoma analysis). In the case of low-quality images, a double level set was applied, in which the first level set was considered to be localization for the OD. Five hundred and fifty images are used to test the algorithm accuracy as well as the agreement among the manual markings of six ophthalmologists. The accuracy of the algorithm in marking the optic disc area and centroid was 83.9%, and the best agreement was observed between the results of the algorithm and manual markings in 379 images. Keywords: optic disc, image segmentation, RIGA dataset, glaucoma, level set, image inpainting

Ahmed Almazroa,1 Sami Alodhayb,2 Kaamran Raahemifar,3 Vasudevan Lakshminarayanan1 1School of Optometry and Vision Science, University of Waterloo, Canada; 2Binrushd Ophthalmic Center, Riyadh, Saudi Arabia; 3Department of Electrical Engineering, Ryerson University, Toronto, Canada Abstract: We introduce here a new technique for segmenting optic cup using two-dimensional fundus images. Cup segmentation is the most challenging part of image processing of the optic nerve head due to the complexity of its structure. Using the blood vessels to segment the cup is important. Here, we report on blood vessel extraction using first a top-hat transform and Otsu’s segmentation function to detect the curves in the blood vessels (kinks) which indicate the cup boundary. This was followed by an interval type-II fuzzy entropy procedure. Finally, the Hough transform was applied to approximate the cup boundary. The algorithm was evaluated on 550 fundus images from a large dataset, which contained three different sets of images, where the cup was manually marked by six ophthalmologists. On one side, the accuracy of the algorithm was tested on the three image sets independently. The final cup detection accuracy in terms of area and centroid was calculated to be 78.2% of 441 images. Finally, we compared the algorithm performance with manual markings done by the six ophthalmologists. The agreement was determined between the ophthalmologists as well as the algorithm. The best agreement was between ophthalmologists one, two and five in 398 of 550 images, while the algorithm agreed with them in 356 images. Keywords: optic cup, image segmentation, glaucoma, blood vessel kinks, fuzzy type-II thresholding, retinal fundus images, optic disk

Before we start dealing with images as discrete measurements, we critically look at how they are measured. The typical aperture shape in today’s image acquisition equipment is square, as it is easy to fabricate on a detector chip. Koenderink [17] already noted in the 1980s that such a representation gives rise to “spurious resolution,” the appearance of nonexisting edges and comers. The effect appears clearly when we zoom in to pixel level (Figure 17.1): The face of the author certainly has no square comers all over and sharp edge discontinuities. So what is the shape of the optimal aperture?

Optical beam characterization is an important task for different applications such as imaging, metrology, light-matter interaction, optical communication, etc. An optical beam can encode information in its temporal-frequency spectrum, polarization, spatial structure, and statistical properties. Successful exploitation of the encoding capabilities of light requires the synthesis of beams with specific characteristics and monitoring of their parameters during beam propagation. This Chapter is focused on the characterization of the spatial structure of paraxial quasi-monochromatic scalar beams. The description of such beams by their mutual intensity (MI) is presented in Section 2. In Section 3 the transformation of the MI of beam during its propagation through first-order optical systems, often called ABCD systems, is studied. Note that the first-order optical systems are completely described by their ray transformation matrix. Along this Chapter we will use this matrix formalism which significantly simplifies the solutions of many discussed problems. The Wigner distribution (WD) provides an alternative way for beam characterization exploring the concept of phase space. Its definition and transformation under beam propagation is considered in Section 4. Neither the MI nor the WD can be measured directly, and their reconstruction is a cumbersome task. A more accessible characterization of beams via the moments of the WD is presented in Section 5. These moments are grouped in orders such that the lower the order the more global beam characteristics it represents. The physical meaning and properties of firstand second-order moments are discussed in Section 6. In Section 7 the Poincare sphere is introduced for classification and comparison of optical beams.

By combining the definition of the Wigner distribution function (WDF) and the matrix method of optical system modeling, we can evaluate the transformation of the former in centered systems with great complexity. The effect of stops and lens diameter are also considered and are shown to be responsible for non-linear clipping of the resulting WDF in the case of coherent illumination and non-linear modulation of the WDF when the illumination is incoherent. As an example, the study of a single lens imaging systems illustrates the applicability of the method., 16 pages, 7 figures. To appear in J. of Comp. and Appl. Math