Content-Based Colour Transfer

International audienceThis paper presents a novel content-based method for transferring the colour patterns between images. Unlike previous methods that rely on image colour statistics, our method puts an emphasis on high-level scene content analysis. We first automatically extract the foreground subject areas and background scene layout from the scene. The semantic correspondences of the regions between source and target images are established. In the second step, the source image is re-coloured in a novel optimization framework, which incorporates the extracted content information and the spatial distributions of the target colour styles. A new progressive transfer scheme is proposed to integrate the advantages of both global and local transfer algorithms, as well as avoid the over-segmentation artefact in the result. Experiments how that with a better understanding of the scene contents, our method well preserves the spatial layout, the colour distribution and the visual coherence in the transfer process. As an interesting extension, our method can also be used to re-colour video clips with spatially-varied colour effects

Multiplicity Structure of the Hadronic Final State in Diffractive Deep-Inelastic Scattering at HERA

The multiplicity structure of the hadronic system X produced in deep-inelastic processes at HERA of the type ep -> eXY, where Y is a hadronic system with mass M_Y< 1.6 GeV and where the squared momentum transfer at the pY vertex, t, is limited to |t|<1 GeV^2, is studied as a function of the invariant mass M_X of the system X. Results are presented on multiplicity distributions and multiplicity moments, rapidity spectra and forward-backward correlations in the centre-of-mass system of X. The data are compared to results in e+e- annihilation, fixed-target lepton-nucleon collisions, hadro-produced diffractive final states and to non-diffractive hadron-hadron collisions. The comparison suggests a production mechanism of virtual photon dissociation which involves a mixture of partonic states and a significant gluon content. The data are well described by a model, based on a QCD-Regge analysis of the diffractive structure function, which assumes a large hard gluonic component of the colourless exchange at low Q^2. A model with soft colour interactions is also successful.Comment: 22 pages, 4 figures, submitted to Eur. Phys. J., error in first submission - omitted bibliograph

Controlling Perceptual Factors in Neural Style Transfer

Neural Style Transfer has shown very exciting results enabling new forms of image manipulation. Here we extend the existing method to introduce control over spatial location, colour information and across spatial scale. We demonstrate how this enhances the method by allowing high-resolution controlled stylisation and helps to alleviate common failure cases such as applying ground textures to sky regions. Furthermore, by decomposing style into these perceptual factors we enable the combination of style information from multiple sources to generate new, perceptually appealing styles from existing ones. We also describe how these methods can be used to more efficiently produce large size, high-quality stylisation. Finally we show how the introduced control measures can be applied in recent methods for Fast Neural Style Transfer.Comment: Accepted at CVPR201

Lyman-alpha line and continuum radiative transfer in a clumpy interstellar medium

Aims: We aim to study the effects of an inhomogeneous interstellar medium (ISM) on the strength and the shape of the Lyman alpha (Lya) line in starburst galaxies. Methods: Using our 3D Monte Carlo Lya radiation transfer code, we study the radiative transfer of Lya, UV and optical continuum photons in homogeneous and clumpy shells of neutral hydrogen and dust surrounding a central source. Our simulations predict the Lya and continuum escape fraction, the Lya equivalent width EW(Lya), the Lya line profile and their dependence on the gas geometry and the main input physical parameters. Results: The ISM clumpiness is found to have a strong impact on the Lya line radiative transfer, entailing a strong dependence of the emergent features of the Lya line (escape fraction, EW(Lya)) on the ISM morphology. Although a clumpy and dusty ISM appears more transparent to radiation (both line and continuum) compared to an equivalent homogeneous ISM of equal dust optical depth, we find that the Lya photons are, in general, still more attenuated than UV continuum radiation. As a consequence, the observed Lya equivalent width (EWobs(Lya)) is lower than the intrinsic one (EWint(Lya)) for nearly all clumpy ISM configurations considered. There are, however, special conditions under which Lya photons escape more easily than the continuum, resulting in an enhanced EWobs(Lya). The requirement for this to happen is that the ISM is almost static (galactic outflows < 200 km/s), extremely clumpy (with density contrasts >10^7 in HI between clumps and the interclump medium), and very dusty (E(B-V) > 0.30). When these conditions are fulfilled the emergent Lya line profile shows no velocity shift and little asymmetry. Given the asymmetry and velocity shifts generally observed in starburst galaxies with Lya emission, we conclude that clumping is unlikely to significantly enhance their relative Lya/UV transmission.Comment: 20 pages, 22 figures. Accepted for publication in A&

Effect of curing conditions and harvesting stage of maturity on Ethiopian onion bulb drying properties

The study was conducted to investigate the impact of curing conditions and harvesting stageson the drying quality of onion bulbs. The onion bulbs (Bombay Red cultivar) were harvested at three harvesting stages (early, optimum, and late maturity) and cured at three different temperatures (30, 40 and 50 oC) and relative humidity (30, 50 and 70%). The results revealed that curing temperature, RH, and maturity stage had significant effects on all measuredattributesexcept total soluble solids

Drying kinetics and physico-chemical quality of mango slices

Mango (Mangifera indica L.) is an important tropical fruit consumed worldwide and grown in Italy only in Sicily, where the areas of the Tyrrhenian coast have proved to be suitable to produce valuable fruits. Mango fruit has a pleasant aroma and taste, which are important qualities for consumer’s sensorial acceptance. However, they are highly perishable, prone to progressive undesired changes if stored untreated, resulting in around 25% postharvest losses, which is further increased during storage and transportation. An alternative for reducing the above-mentioned undesired changes is the dehydration of the cut fruit, which reduce the fruit water activity, thereby avoiding the deteriorative process and extending the shelf-life. This study investigates the effect of dehydration at different temperatures (50, 60 and 70°C) on drying kinetics and volatile compounds of two cultivars (Keitt and Osteen) of mango fruits cultivated in Sicily. Significant losses of volatile constituents of fresh mango occurred at higher temperature, especially for the Osteen cultivar. A diffusion model including the effect of shrinkage is also proposed, which may be used to describe drying behaviour of fruits and to define the optimal drying conditions.. Experimental data of the moisture ratio during drying were well predicted by the model