Visually lossless compression of digital hologram sequences

Digital hologram sequences have great potential for the recording of 3D scenes of moving macroscopic objects as their numerical reconstruction can yield a range of perspective views of the scene. Digital holograms inherently have large information content and lossless coding of holographic data is rather inefficient due to the speckled nature of the interference fringes they contain. Lossy coding of still holograms and hologram sequences has shown promising results. By definition, lossy compression introduces errors in the reconstruction. In all of the previous studies, numerical metrics were used to measure the compression error and through it, the coding quality. Digital hologram reconstructions are highly speckled and the speckle pattern is very sensitive to data changes. Hence, numerical quality metrics can be misleading. For example, for low compression ratios, a numerically significant coding error can have visually negligible effects. Yet, in several cases, it is of high interest to know how much lossy compression can be achieved, while maintaining the reconstruction quality at visually lossless levels. Using an experimental threshold estimation method, the staircase algorithm, we determined the highest compression ratio that was not perceptible to human observers for objects compressed with Dirac and MPEG- 4 compression methods. This level of compression can be regarded as the point below which compression is perceptually lossless although physically the compression is lossy. It was found that up to 4 to 7.5 fold compression can be obtained with the above methods without any perceptible change in the appearance of video sequences

Suppression of the in vitro growth and development of Microdochium nivale by phosphite

© 2018 British Society for Plant Pathology The ascomycete fungus Microdochium nivale is a major pathogen of many species of the gramineae. Control measures rely heavily on chemical fungicides, making alternative means of disease reduction desirable. Phosphite (PO33−), has proven efficacy in reducing susceptibility of different species of gramineae to oomycetes, and has adverse effects on the invitro growth of numerous other pathogens. The effect of phosphorous acid (H3PO3), phosphoric acid (H3PO4), dihydrogen potassium phosphite (KH2PO3), dihydrogen potassium phosphate (KH2PO4) and potassium hydroxide (KOH) on the invitro mycelial growth and development of M. nivale was determined. Radial growth on amended potato dextrose agar (PDA) was used to calculate mean daily growth and percentage inhibition. PO33− had a significant inhibitory effect on mycelial growth, with EC50 values ranging between 35.9 and 40.99μgmL−1, whilst PO43− and KOH had no significant inhibitory effect. Microscopic examination of mycelia showed morphological deformities in hyphae growing on PO33− amended PDA, whilst hyphal growth was normal on PO43− and KOH amended PDA. Conidial germination of M. nivale was significantly reduced following immersion in solutions of 50, 100 and 250μgmL−1 of PO33−, while PO43− and KOH at the same concentrations induced no inhibitory affect. These results show that PO33− is a significant inhibitor of the growth of M. nivale and may have the potential to be used as a chemical control agent in the field

Measurement, modelling, and closed-loop control of crystal shape distribution: Literature review and future perspectives

Crystal morphology is known to be of great importance to the end-use properties of crystal products, and to affect down-stream processing such as filtration and drying. However, it has been previously regarded as too challenging to achieve automatic closed-loop control. Previous work has focused on controlling the crystal size distribution, where the size of a crystal is often defined as the diameter of a sphere that has the same volume as the crystal. This paper reviews the new advances in morphological population balance models for modelling and simulating the crystal shape distribution (CShD), measuring and estimating crystal facet growth kinetics, and two- and three-dimensional imaging for on-line characterisation of the crystal morphology and CShD. A framework is presented that integrates the various components to achieve the ultimate objective of model-based closed-loop control of the CShD. The knowledge gaps and challenges that require further research are also identified

Influence de cinq stimuli-couleurs sur la réponse électrodermale

Darakis Léo. Influence de cinq stimuli-couleurs sur la réponse électrodermale. In: Bulletin de psychologie, tome 30 n°329, 1977. Nouvelles perspectives en psychologie de l'art. pp. 760-766

Advanced digital holographic data compression methods

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Phosethyl-Al et phosphite, leurs activites directe et indirecte sur la pathogenie des Phytophthora spp

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Compression of digital hologram sequences using MPEG-4

Recording and real time reconstruction of digital hologram sequences have recently become feasible. The amount of information that such hologram sequences contain results in voluminous data files, rendering their storage and transmission impractical. As a result, compression of digital hologram sequences is of utmost importance for practical applications of hologram sequences. In the absence of a specific hologram sequence compression technique, a first concern is how a high-performance conventional video compression technique would perform. Such a technique would not be optimized for hologram sequences but would provide a threshold that all hologram sequence compression techniques should reach. In this paper, the use of MPEG-4 part 2 video coding algorithm for the compression of hologram sequences is investigated. Although the algorithm was originally developed for the compression of ordinary video, we apply it on digital hologram sequences and investigate its performance. For this, appropriate digital hologram sequences are used to asses how the coding algorithm affects their information content. In addition, we investigate whether MPEG-4 interframe coding, which aims to achieve compression by exploiting similarities across adjacent frames of the sequence, offers any advantage compared to intraframe coding, where each frame is coded independently. Results show that the MPEG-4 coding algorithm can successfully compress hologram sequences to compression rates of ∼ 20 : 1 while retaining the reconstruction quality of the hologram sequences

Use of fresnelets for phase shifting digital hologram compression

Fresnelets are wavelet-like base functions specially tailored for digital holography applications. We introduce their use in phase-shifting interferometry (PSI) digital holography for the compression of such holographic data. Two compression methods are investigated. One uses uniform quantization of the Fresnelet coefficients followed by lossless coding, and the other uses set portioning in hierarchical trees (SPIHT) coding. Quantization and lossless coding of the original data is used to compare the performance of the proposed algorithms. The comparison reveals that the Fresnelet transform of phase-shifting holograms in combination with SPIHT or uniform quantization can be used very effectively for the compression of holographic data. The performance of the new compression schemes is demonstrated on real PSI digital holographic data