Plast Reconstr Surg Glob Open
December 2024
Photoacoustic imaging (PAI) can evaluate lymphatic vessels with a high resolution (0.2 mm) compared with other methods. LUB0, a new PAI device that is smaller than the PAI-05 used since 2020 (both from Luxonus, Inc.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
December 2023
Spectral photoacoustic imaging (PAI) is a new technology that is able to provide 3D geometric structure associated with 1D wavelength-dependent absorption information of the interior of a target in a non-invasive manner. It has potentially broad applications in clinical and medical diagnosis. Unfortunately, the usability of spectral PAI is severely affected by a time-consuming data scanning process and complex noise.
View Article and Find Full Text PDFSkin is composed of different layers, including the stratum corneum, epidermal living layer and papillary and reticular dermis. Each has specific optical properties due to differences in their biological components. Alterations in the skin's cutaneous biological components resulting from photoaging caused by chronic exposure to UV light affect the deterioration of appearance associated with the skin's optical properties.
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July 2023
Reconstruction of high dynamic range image from a single low dynamic range image captured by a conventional RGB camera, which suffers from over- or under-exposure, is an ill-posed problem. In contrast, recent neuromorphic cameras like event camera and spike camera can record high dynamic range scenes in the form of intensity maps, but with much lower spatial resolution and no color information. In this article, we propose a hybrid imaging system (denoted as NeurImg) that captures and fuses the visual information from a neuromorphic camera and ordinary images from an RGB camera to reconstruct high-quality high dynamic range images and videos.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
August 2021
This paper proposes a method to estimate depth from a single multispectral image by using a lens property known as chromatic aberration. Chromatic aberration causes light passing through a lens to be refracted depending on the wavelength. The refraction causes the angle of rays to vary depending on their wavelength and a change in focal length, which leads to a defocus blur for different wavelengths.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
August 2021
This paper introduces a novel depth recovery method based on light absorption in water. Water absorbs light at almost all wavelengths whose absorption coefficient is related to the wavelength. Based on the Beer-Lambert model, we introduce a bispectral depth recovery method that leverages the light absorption difference between two near-infrared wavelengths captured with a distant point source and orthographic cameras.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
February 2021
Here, we propose a novel method to estimate the parameters of non-planar objects with thin film surfaces. Being able to estimate the optical parameters of objects with thin film surfaces has a wide range of applications from industrial inspections to biological and archaeology research. However, there are many challenging issues that need to be overcome to model such parameters.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
January 2021
This paper presents a precise, stable, and invertible reflectance model for photometric stereo. This microfacet-based model is applicable to all types of isotropic surface reflectance, covering cases from diffusion to specular reflections. We introduce a single variable to physically quantify the surface smoothness, and by monotonically sliding this variable between 0 and 1, our model enables a versatile representation that can smoothly transform between an ellipsoid of revolution and the equation for Lambertian reflectance.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
December 2022
Recognizing wet surfaces and their degrees of wetness is essential for many computer vision applications. Surface wetness can inform us slippery spots on a road to autonomous vehicles, muddy areas of a trail to humanoid robots, and the freshness of groceries to us. The fact that surfaces darken when wet, i.
View Article and Find Full Text PDFRecently, many hyperspectral (HS) image superresolution methods that merge a low spatial resolution HS image and a high spatial resolution three-channel RGB image have been proposed in spectral imaging. A largely ignored fact is that most existing commercial RGB cameras capture high resolution images by a single CCD/CMOS sensor equipped with a color filter array (CFA). In this paper, we account for the common imaging mechanism of commercial RGB cameras, and propose to use a mosaic RGB image for HS image super-resolution, which prevents demosaicing error and thus its propagation into the HS image super-resolution results.
View Article and Find Full Text PDFWe present a single-capture photometric stereo method using a hyperspectral camera. A spectrally and spatially designed illumination enables a point-wise estimation of reflectance spectra and surface normals from a single hyperspectral image. The illumination works as a reflectance probe in wide spectral regions where reflectance spectra are measured, and the full spectra are estimated by interpolation.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
January 2018
We propose uncalibrated photometric stereo methods that address the problem due to unknown isotropic reflectance. At the core of our methods is the notion of "constrained half-vector symmetry" for general isotropic BRDFs. We show that such symmetry can be observed in various real-world materials, and it leads to new techniques for shape and light source estimation.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
July 2016
In recent years, fluorescence analysis of scenes has received attention in computer vision. Fluorescence can provide additional information about scenes, and has been used in applications such as camera spectral sensitivity estimation, 3D reconstruction, and color relighting. In particular, hyperspectral images of reflective-fluorescent scenes provide a rich amount of data.
View Article and Find Full Text PDFIEEE Trans Pattern Anal Mach Intell
October 2015
We propose an uncalibrated photometric stereo method that works with general and unknown isotropic reflectances. Our method uses a pixel intensity profile, which is a sequence of radiance intensities recorded at a pixel under unknown varying directional illumination. We show that for general isotropic materials and uniformly distributed light directions, the geodesic distance between intensity profiles is linearly related to the angular difference of their corresponding surface normals, and that the intensity distribution of the intensity profile reveals reflectance properties.
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May 2016
Hyperspectral imaging is beneficial to many applications but most traditional methods do not consider fluorescent effects which are present in everyday items ranging from paper to even our food. Furthermore, everyday fluorescent items exhibit a mix of reflection and fluorescence so proper separation of these components is necessary for analyzing them. In recent years, effective imaging methods have been proposed but most require capturing the scene under multiple illuminants.
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December 2013
Traditionally, researchers tend to exclude fluorescence from color appearance algorithms in computer vision and image processing because of its complexity. In reality, fluorescence is a very common phenomenon observed in many objects, from gems and corals, to different kinds of writing paper, and to our clothes. In this paper, we provide detailed theories of fluorescence phenomenon.
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