147,687 research outputs found
Class-Agnostic Counting
Nearly all existing counting methods are designed for a specific object
class. Our work, however, aims to create a counting model able to count any
class of object. To achieve this goal, we formulate counting as a matching
problem, enabling us to exploit the image self-similarity property that
naturally exists in object counting problems. We make the following three
contributions: first, a Generic Matching Network (GMN) architecture that can
potentially count any object in a class-agnostic manner; second, by
reformulating the counting problem as one of matching objects, we can take
advantage of the abundance of video data labeled for tracking, which contains
natural repetitions suitable for training a counting model. Such data enables
us to train the GMN. Third, to customize the GMN to different user
requirements, an adapter module is used to specialize the model with minimal
effort, i.e. using a few labeled examples, and adapting only a small fraction
of the trained parameters. This is a form of few-shot learning, which is
practical for domains where labels are limited due to requiring expert
knowledge (e.g. microbiology). We demonstrate the flexibility of our method on
a diverse set of existing counting benchmarks: specifically cells, cars, and
human crowds. The model achieves competitive performance on cell and crowd
counting datasets, and surpasses the state-of-the-art on the car dataset using
only three training images. When training on the entire dataset, the proposed
method outperforms all previous methods by a large margin.Comment: Asian Conference on Computer Vision (ACCV), 201
OpenCFU, a New Free and Open-Source Software to Count Cell Colonies and Other Circular Objects
Counting circular objects such as cell colonies is an important source of
information for biologists. Although this task is often time-consuming and
subjective, it is still predominantly performed manually. The aim of the
present work is to provide a new tool to enumerate circular objects from
digital pictures and video streams. Here, I demonstrate that the created
program, OpenCFU, is very robust, accurate and fast. In addition, it provides
control over the processing parameters and is implemented in an in- tuitive and
modern interface. OpenCFU is a cross-platform and open-source software freely
available at http://opencfu.sourceforge.net
Image Processing Instrumentation for Giardia lamblia Detection
Currently, the identification and enumeration of Giardia Iamblia cysts are based upon microscopic methods requiring individuals proficient in this area. It is a tedious process which consumes time that could be constructively used elsewhere. This project attempts to alleviate that burden by employing a computer to automatically process Indirect Fluorescent Antibody (IFA) prepared slides using digital image processing techniques. A computer controlled frame grabber, in conjunction with a CCD TV camera mounted on the epi-fluorescence microscope phototube, captures the light intensities of the objects in view under the microscope objective. The captured image is stored as pixels, with each pixel having a numerical value that can be altered using linear contrast enhancement and bit-slicing to emphasize the cysts and eliminate the majority of unwanted objects from the image. The altered image is then analyzed by a vector trace routine for typical area and perimeters characteristic to Giardia lamblia cysts. Objects in the image matching these characteristics are most likely cysts and are added to a running tally of the number of cysts present on the slide
1SXPS: A deep Swift X-ray Telescope point source catalog with light curves and spectra
We present the 1SXPS (Swift-XRT Point Source) catalog of 151,524 X-ray
point-sources detected by the Swift-XRT in 8 years of operation. The catalog
covers 1905 square degrees distributed approximately uniformly on the sky. We
analyze the data in two ways. First we consider all observations individually,
for which we have a typical sensitivity of ~3e-13 erg/cm2/s (0.3--10 keV). Then
we co-add all data covering the same location on the sky: these images have a
typical sensitivity of ~9e-14 erg/cm2/s (0.3--10 keV). Our sky coverage is
nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ~1.5
less sensitive. The median position error is 5.5" (90% confidence), including
systematics. Our source detection method improves on that used in previous XRT
catalogs and we report >68,000 new X-ray sources. The goals and observing
strategy of the Swift satellite allow us to probe source variability on
multiple timescales, and we find ~30,000 variable objects in our catalog. For
every source we give positions, fluxes, time series (in four energy bands and
two hardness ratios), estimates of the spectral properties, spectra and
spectral fits for the brightest sources, and variability probabilities in
multiple energy bands and timescales.Comment: 27 pages, 19 figures; accepted for publication in ApJS. The
accompanying website, http://www.swift.ac.uk/1SXPS is live; the Vizier entry
should be available shortl
Elliptical Weighted HOLICs for Weak Lensing Shear Measurement. part1:Definitions and isotropic PSF correction
We develop a new method to estimate gravitational shear by adopting an
elliptical weight function to measure background galaxy images. In doing so, we
introduce a new concept of "zero plane" which is an imaginal source plane where
shapes of all sources are perfect circles, and regard the intrinsic shear as
the result of an imaginal lensing distortion. This makes the relation between
the observed shear, the intrinsic shear and lensing distortion more simple and
thus higher-order calculation more easy. The elliptical weight function allows
us to measure the mutiplemoment of shape of background galaxies more precisely
by weighting highly to brighter parts of image and moreover to reduce
systematic error due to insufficient expansion of the weight function in the
original approach of KSB. Point Spread Function(PSF) correction in E-HOLICs
methods becomes more complicated than those in KSB methods. In this paper we
studied isotropic PSF correction in detail. By adopting the lensing distortion
as the ellipticity of the weight function, we are able to show that the shear
estimation in E-HOLICs method reduces to solve a polynomial in the absolute
magnitude of the distortion. We compare the systematic errors between our
approach and KSB using STEP2 simulation. It is confirmed that KSB method
overestimate the input shear for images with large ellipticities, and E-HOLICs
correctly estimate the input shear even for such images. Anisotropic PSF
correction and analysis of real data will be presented in forthcoming paper.Comment: 30 pages, 8 figures, submitted to Ap
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