2,437 research outputs found

    PHOTOGRAMMETRY DRIVEN TOOLS TO SUPPORT THE RESTORATION OF OPEN-AIR BRONZE SURFACES OF SCULPTURES: AN INTEGRATED SOLUTION STARTING FROM THE EXPERIENCE OF THE NEPTUNE FOUNTAIN IN BOLOGNA

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    Checking the irreversible process of clean-up is a delicate task that requires a work of synthesis between theoretical knowledge and practical experience, to define an effective operating protocol on a limited patch area to be extended later to the entire artefact's surface. In this paper, we present a new, quick, semi-automated 3D photogrammetry-based solution to support restorers in the open-air bronze artwork cleaning from corrosion and weathering decay. The solution allows the conservators to assess in real time and with a high level of fidelity in colour and shape, the 'surfaces' to be cleaned before, during and after the clear-out treatment. The solution besides allows an effective and valuable support tool for restorers to identify the original layer of the bronze surface, developed and validated during the ongoing restoration of the Neptune Fountain in Bologna

    Spectral modeling of a six-color inkjet printer

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    After customizing an Epson Stylus Photo 1200 by adding a continuous-feed ink system and a cyan, magenta, yellow, black, orange and green ink set, a series of research tasks were carried out to build a full spectral model of the printers output. First, various forward printer models were tested using the fifteen two color combinations of the printer. Yule- Nielsen-spectral-Neugebauer (YNSN) was selected as the forward model and its accuracy tested throughout the colorant space. It was found to be highly accurate, performing as well as a more complex local, cellular version. Next, the performance of nonlinear optimization-routine algorithms were evaluated for their ability to efficiently invert the YNSN model. A quasi-Newton based algorithm designed by Davidon, Fletcher and Powell (DFP) was found to give the best performance when combined with starting values produced from the non-negative least squares fit of single-constant Kubelka- Munk. The accuracy of the inverse model was tested and different optimization objective functions were evaluated. A multistage objective function based on minimizing spectral RMS error and then colorimetric error was found to give highly accurate matches with low metameric potential. Finally, the relationship between the number of printing inks and the ability to eliminate metamerism was explored

    Characterization of Starch by Vibrational Spectroscopy

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    To develop a dispersive Raman spectroscopic method for measuring amylose-amylopectin ratios of corn starch mixtures, 67 mixtures were prepared by randomly mixing waxy and normal corn starches. Amylose contents were measured using a dual wavelength iodine binding colorimetric method. Raman data were collected from 250 to 3200 cm-1 using optimized instrument parameters. Partial least-squares (PLS) and principal components regression (PCR) were used to prepare multivariate calibration models; however, PLS commonly outperformed PCR. Truncating the spectra to 250 to 2000 cm-1 improved the results (r2 of validation = 0.831, SEP = 2.90%). Removal of a cold water swelling starch from the data also offered a slight improvement in results (r2 of validation = 0.860, SEP = 2.70%). Dispersive Raman spectroscopy may not be well suited for quantifying amylose content of starch mixtures; however, the method was easily capable of discriminating between waxy and normal starches. This may allow the method to be used for confirming the identity of starch shipments. A dispersive Raman spectroscopic method for measuring retrogradation in corn starch gels was investigated. Thirty-six gels were prepared, stored at 4° C and measured at regular time intervals (0 h, 24 h, 48 h, 72 h, 120 h, 168 h after preparation). After each measurement, the gels were freeze-dried, then each resultant dried gel was ground into a powder and measured using X-ray diffraction. Relative crystallinity was determined, and intensity changes in the Raman band at 480 cm-1 were measured. No correlation was found between changes in the 480 cm-1 band and the relative crystallinity of the gels (r2 \u3c .1). The low starch concentration used may have caused the poor Raman signal strength and the unpredictable changes in the X-ray diffraction data. The experiment found that measuring retrogradation in very dilute starch gels could be problematic, and that more development is needed in order to apply Raman spectroscopy to in a food system like white pan bread. Advisor: Randy Wehlin

    An Adaptive Skin Detection Approach of Face Images with Unequal Luminance, Color Excursion, and Background Interference

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    Face detection and recognition are affected greatly by unequal luminance, color excursion and background interference. For improving skin detection rates of color face images in the presence of unequal luminance, color excursion and background interference, this paper proposes an approach for automatic skin detection. This approach globally corrects the color excursion using the X, Y, Z color components. Then it establishes a self-adaptive nonlinear amendment function using the a', b'and L' components, and locally corrects the R, G, B color components of row-column transformed sub-block images to balance the global luminance and color. Finally, it constructs an L'a'b'three-dimensional semi-supervised dual-probability skin model, based on which automatic skin detection can be realized. The experimental results demonstrated that this approach has great adaptability, a high detection rate and speed

    Unsupervised Extraction of Stable Expression Signatures from Public Compendia with an Ensemble of Neural Networks

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    Cross-experiment comparisons in public data compendia are challenged by unmatched conditions and technical noise. The ADAGE method, which performs unsupervised integration with denoising autoencoder neural networks, can identify biological patterns, but because ADAGE models, like many neural networks, are over-parameterized, different ADAGE models perform equally well. To enhance model robustness and better build signatures consistent with biological pathways, we developed an ensemble ADAGE (eADAGE) that integrated stable signatures across models. We applied eADAGE to a compendium of Pseudomonas aeruginosa gene expression profiling experiments performed in 78 media. eADAGE revealed a phosphate starvation response controlled by PhoB in media with moderate phosphate and predicted that a second stimulus provided by the sensor kinase, KinB, is required for this PhoB activation. We validated this relationship using both targeted and unbiased genetic approaches. eADAGE, which captures stable biological patterns, enables cross-experiment comparisons that can highlight measured but undiscovered relationships.Gordon and Betty Moore Foundation (GBMF 4552)National Institutes of Health (U.S.) (grant R01-AI091702)Cystic Fibrosis Foundation (STANTO15R0

    Deep White-Balance Editing

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    We introduce a deep learning approach to realistically edit an sRGB image's white balance. Cameras capture sensor images that are rendered by their integrated signal processor (ISP) to a standard RGB (sRGB) color space encoding. The ISP rendering begins with a white-balance procedure that is used to remove the color cast of the scene's illumination. The ISP then applies a series of nonlinear color manipulations to enhance the visual quality of the final sRGB image. Recent work by [3] showed that sRGB images that were rendered with the incorrect white balance cannot be easily corrected due to the ISP's nonlinear rendering. The work in [3] proposed a k-nearest neighbor (KNN) solution based on tens of thousands of image pairs. We propose to solve this problem with a deep neural network (DNN) architecture trained in an end-to-end manner to learn the correct white balance. Our DNN maps an input image to two additional white-balance settings corresponding to indoor and outdoor illuminations. Our solution not only is more accurate than the KNN approach in terms of correcting a wrong white-balance setting but also provides the user the freedom to edit the white balance in the sRGB image to other illumination settings.Comment: Accepted as Oral at CVPR 202

    Developing a spectral and colorimetric database of artist paint materials

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    As the project of the author\u27s Master\u27s thesis, the development of a spectral and colorimetric database of artist paint materials for acrylic paints was started. The goal of this research project was to: - provide the academic resource of colorant spectral characteristics - give scientifc explanations on various paint-particular phenomena (paint mixing, gloss effects and color gamut expansion by varnishing) These tasks were planned to satisfy possible interests on paint research from not only conservators in museums but also color educators in schools and color reproduction engineers in imaging companies
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