Feature Activation Map: Visual Explanation of Deep Learning Models for Image Classification

Decisions made by convolutional neural networks(CNN) can be understood and explained by visualizing discriminative regions on images. To this end, Class Activation Map (CAM) based methods were proposed as powerful interpretation tools, making the prediction of deep learning models more explainable, transparent, and trustworthy. However, all the CAM-based methods (e.g., CAM, Grad-CAM, and Relevance-CAM) can only be used for interpreting CNN models with fully-connected (FC) layers as a classifier. It is worth noting that many deep learning models classify images without FC layers, e.g., few-shot learning image classification, contrastive learning image classification, and image retrieval tasks. In this work, a post-hoc interpretation tool named feature activation map (FAM) is proposed, which can interpret deep learning models without FC layers as a classifier. In the proposed FAM algorithm, the channel-wise contribution weights are derived from the similarity scores between two image embeddings. The activation maps are linearly combined with the corresponding normalized contribution weights, forming the explanation map for visualization. The quantitative and qualitative experiments conducted on ten deep learning models for few-shot image classification, contrastive learning image classification and image retrieval tasks demonstrate the effectiveness of the proposed FAM algorithm.Comment: 14 page

Image Feature Information Extraction for Interest Point Detection: A Comprehensive Review

Interest point detection is one of the most fundamental and critical problems in computer vision and image processing. In this paper, we carry out a comprehensive review on image feature information (IFI) extraction techniques for interest point detection. To systematically introduce how the existing interest point detection methods extract IFI from an input image, we propose a taxonomy of the IFI extraction techniques for interest point detection. According to this taxonomy, we discuss different types of IFI extraction techniques for interest point detection. Furthermore, we identify the main unresolved issues related to the existing IFI extraction techniques for interest point detection and any interest point detection methods that have not been discussed before. The existing popular datasets and evaluation standards are provided and the performances for eighteen state-of-the-art approaches are evaluated and discussed. Moreover, future research directions on IFI extraction techniques for interest point detection are elaborated

Selected Topics in Advanced Optical Design and Engineering

Optical imaging has seen significant development over the last few decades thanks to the advances of light sources and innovative imaging modalities. New quests have opened for advanced optical system design and engineering that require comprehensive understanding of theory and extensive computer simulations. This dissertation discusses several selected topics in advanced optical design and engineering, including new optical design considerations for systems with ultrafast illumination, engineering of a reflective microscope system in the vacuum ultraviolet and a method to design apochromat and superachromat objectives. For optical systems with ultrafast illumination, a modified definition of Strehl ratio is proposed to quantify chromatic and temporal behavior of ultrafast laser pulses at the optical focus. A simple method to obtain approximate numerical solutions is given with the help of ray tracing software. Effects of monochromatic aberrations, material dispersion up to the second order and pupil aberrations are discussed. System engineering of an imaging microscope illuminated with hydrogen Lyman-α line at 121.6nm is discussed. Challenges of diamond turning fabrication technology are described. Alignment and testing procedures are presented. A correction phase plate design is proposed for improving the as-built system performance, and a sensitivity analysis is carried out. For future work, a new two-stage system design is proposed to address the limitations of the current system. A simple method to design apochromats is proposed, where an apochromat is formed by combining two achromatic doublets with proper scaling of the focal lengths. A scaling formula is derived to calculate the focal lengths of each component. The formula is developed for lenses in contact and remote lenses with different marginal ray heights.Release after 01/27/201

Selected Topics in Advanced Optical Design and Engineering

Optical imaging has seen significant development over the last few decades thanks to the advances of light sources and innovative imaging modalities. New quests have opened for advanced optical system design and engineering that require comprehensive understanding of theory and extensive computer simulations. This dissertation discusses several selected topics in advanced optical design and engineering, including new optical design considerations for systems with ultrafast illumination, engineering of a reflective microscope system in the vacuum ultraviolet and a method to design apochromat and superachromat objectives. For optical systems with ultrafast illumination, a modified definition of Strehl ratio is proposed to quantify chromatic and temporal behavior of ultrafast laser pulses at the optical focus. A simple method to obtain approximate numerical solutions is given with the help of ray tracing software. Effects of monochromatic aberrations, material dispersion up to the second order and pupil aberrations are discussed. System engineering of an imaging microscope illuminated with hydrogen Lyman-? line at 121.6nm is discussed. Challenges of diamond turning fabrication technology are described. Alignment and testing procedures are presented. A correction phase plate design is proposed for improving the as-built system performance, and a sensitivity analysis is carried out. For future work, a new two-stage system design is proposed to address the limitations of the current system. A simple method to design apochromats is proposed, where an apochromat is formed by combining two achromatic doublets with proper scaling of the focal lengths. A scaling formula is derived to calculate the focal lengths of each component. The formula is developed for lenses in contact and remote lenses with different marginal ray heights

Strehl ratio for optical systems with ultrafast illumination

We study ultrafast laser pulse properties as they propagate through optical systems. A modified definition of Strehl ratio is used to quantify the chromatic and temporal behavior of ultrafast laser pulses at the optical focus. We propose this parameter as a figure of merit for the design and analysis of optical systems with ultrafast illumination. A simple method to obtain approximate numerical solutions is given with the help of ray tracing software. Effects of monochromatic aberrations and material dispersion up to the second order are discussed. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.Open access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Air lens vs aspheric surface: a lens design case study

We discuss the behavior of air lenses in lens design. The structural aberration coefficients of a thin air lens are derived and compared with their glass thin lens counterpart. Examples are provided for a telephoto lens and the Monochromatic Quartet where air lenses or aspheric surfaces are used.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Compact, unit magnification, reflective imaging relay using freeform surfaces

We present a design for a unit magnification imaging relay that is compact. The design uses two mirrors, and one is used by light twice for a three-reflection system. The mirrors are specified with freeform surfaces. There are several tradeoffs of performance depending on field of view, F/#, and wavelength range. One example provides a 30-mm circular field of view at F/2.8, and another example provides a circular field of view of 40 mm in diameter at F/4 for a length of similar to 400 mm. Adding a third nearly flat mirror allows a system to provide a 50-mm field of view at F/4 for a length of 420 mm. A last example includes a beam splitter cube to allow accessing the full field of view. These systems are diffraction limited at 550 nm.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Supplementary material: Strehl ratio for optical systems with ultrafast illumination

This fileset contains supplementary material for paper titled "Strehl ratio for optical systems with ultrafast illumination"<div><div><br></div><div><br></div><div>Last Updated in JUN 2018 by Weichuan Gao</div></div

Optical design and system characterization of an imaging microscope at 121.6 nm

We present the optical design and system characterization of an imaging microscope prototype at 121.6 nm. System engineering processes are demonstrated through the construction of a Schwarzschild microscope objective, including tolerance analysis, fabrication, alignment, and testing. Further improvements on the as-built system with a correction phase plate are proposed and analyzed. Finally, the microscope assembly and the imaging properties of the prototype are demonstrated.National Science Foundation (NSF) [1306921]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]