Search results for "Methodologie"
showing 10 items of 2141 documents
Scanning microscopy with spatial sampling of the detector plane
2013
We present the implementation of a confocal scanning microscope in which the signal detection is performed through a matrix sensor, specifically, a CCD camera. This kind of detection has several advantages over the conventional detection in confocal microscopes. One of those advantages is the possibility to recover information of the sample that vanishes when the confocal image is directly acquired by the integration of light into a signal. We demonstrate the applicability of the system which allows implementing super-resolution techniques in a very easy manner.
One-dimensional wavelength multiplexed microscope without objective lens
2009
A new approach aimed to achieve microscopic imaging without objective lenses and based on wavelength multiplexing of the spatial object information is presented. The proposed method is used to develop, construct and experimentally validate a new type of optical microscope having no objective lens and no numerical reconstruction algorithms to allow imaging process. In order to extract the collected spatial information we use a spectrometer as part of our microscope system. Preliminary results are presented while considering two different types of one-dimensional (1-D) objects.
Fourier-domain lightfield microscopy: a new paradigm in 3D microscopy
2020
Recently, integral (also known as lightfield or plenoptic) imaging concept has been applied successfully to microscopy. The main advantage of lightfield microscopy when compared with conventional 3D imaging techniques is that it offers the possibility of capturing the 3D information of the sample after a single shot. However, integral microscopy is now facing many challenges, like improving the resolution and depth of field of the reconstructed specimens or the development and optimization of specially-adapted reconstruction algorithms. This contribution is devoted to review a new paradigm in lightfield microscopy, namely, the Fourier-domain integral microscope (FiMic), that improves the ca…
Robust Depth Estimation for Light Field Microscopy
2019
Light field technologies have seen a rise in recent years and microscopy is a field where such technology has had a deep impact. The possibility to provide spatial and angular information at the same time and in a single shot brings several advantages and allows for new applications. A common goal in these applications is the calculation of a depth map to reconstruct the three-dimensional geometry of the scene. Many approaches are applicable, but most of them cannot achieve high accuracy because of the nature of such images: biological samples are usually poor in features and do not exhibit sharp colors like natural scene. Due to such conditions, standard approaches result in noisy depth ma…
Novel GaN Based Solid State Power Amplifiers, Results, Advances and Comparison with Vacuum Tubes Based Microwave Power Modules
2018
Power amplifiers based on vacuum tubes or solid state are key items in a number of systems. Solid state technology is growing up for some applications and it may be complementary to the vacuum technology. This paperwork presents SSPA operational principles and performance. The GaN technology available in the market, the technology roadmap, a comparison with the vacuum tubes are introduced
Comparison of perceptually uniform quantisation with average error minimisation in image transform coding
1999
An alternative transform coder design criterion based on restricting the maximum perceptual error of each coefficient is proposed. This perceptually uniform quantisation of the transform domain ensures that the perceptual error will be below a certain limit regardless of the particular input image. The results show that the proposed criterion improves the subjective quality of the conventional average error criterion even if it is weighted with the same perceptual metric.
A Novel Iris Recognition System based on Micro-Features
2007
In this paper a novel approach for iris recognition system based on iris micro-features is proposed. The proposed system follows the minutiae based approach developed for fingerprint recognition systems. The proposed system uses four iris microfeatures, considered as minutiae, for identification. The individualized characteristics are nucleus, collarette, valleys and radius. Iris recognition is divided in three main phases: image preprocessing, micro-features extraction and matching. The algorithm has been tested on CASIA v1.0 iris image database obtaining an high accuracy. The obtained experimental results have been analyzed and compared with the Daugman based approach.
Image enhancement in simple fingerprint minutiae extraction algorithm using crossing number on valley structure
2007
In fingerprint recognition system, fingerprint feature extraction algorithm requires good quality fingerprint images to produce good results. Therefore, one step in the preprocessing stage is image enhancement to improve the quality of poor fingerprint image, so the minutiae points can be detected with good results. In this paper, we present how this enhancement process in simple minutiae detection algorithm using crossing number on valley structure improves detection of true minutiae.
Simple Fingerprint Minutiae Extraction Algorithm Using Crossing Number On Valley Structure
2007
Most of the existing fingerprint extraction techniques currently available are based on ridge structure. The ridge usually has thicker structure than the valley, so that more processing time is needed to extract the ridge than extracting the valley. Taking the advantage of the thin structure of the valley, we proposed an algorithm that reduces the time needed for minutiae extraction. The algorithm was developed in Matlab environment using fingerprint images from FVC2004. In order to show the performance of the algorithm, numerical results are presented.
Fingerprint image enhancement using directional morphological filter
2005
Fingerprint images quality enhancement is a topic phase to ensure good performance in an automatic fingerprint identification system (AFIS) based on minutiae matching. In this paper a new fingerprint enhancement algorithm based on morphological filter is introduced. The algorithm is based on three steps: directional decomposition, morphological filter and composition. The performance of the proposed approach has been evaluated on two sets of images: the first one is DB3 database from Fingerprint Verification Competition (FVC) and the second one is self collected using an optical scanner