The present work consists in developing a procedure which will allow to compare gloss values obtained from angularly and spectrally resolved Bidirectional Reflectance Distribution Function (BRDF) measurements and gloss values measured with a national reference goniophotometer. The gloss measurements will be performed on the Reference Goniophotometer for Specular Gloss Calibration available at the Sensor Science Division of the National Institute for Standards and Technology (NIST), whereas the BRDF measurements will be conducted on the Five-Axis Goniometer for Color & Appearance also available at the same division of NIST.

A system for simultaneously measuring surface normal vectors and BTF (bidirectional texture function) profiles of an object is proposed. This system consists of a correlation camera and a spherical scanning light source. The system can compress BTF measurement in one dimension of incidence direction to a single image frame, as well as measure a profile of the BTF under the scanning light source just from a single image frame. Experimental results on an implemented system demonstrate the feasibility of the proposed system.

Fourier optics system have already been recognized as an efficient solution to measure rapidly multispectral bidirectional reflectance distribution function (BRDF) of any kind of surface with very high angular resolution. This capacity is useful to study complex BRDF behaviors in particular for anisotropic surfaces. Measurement of the BRDF polarization dependence is useful to understand better the scattering processes involved in the different types of samples. In the proposed paper we show that polarimetric spectral BRDF (pBRDF) measurements are also possible using such instruments. We evaluate the accuracy of the system using black glass surface. Examples of pBRDF measurements on different types of samples (color shifting paints, car paints and gloss reference samples) are presented.

We demonstrate the sufficiency of using as few as five LEDs of distinct spectra for color-accurate multispectral lighting reproduction and solve for the optimal set of five from 11 such commercially available LEDs. We leverage published spectral reflectance, illuminant, and camera spectral sensitivity datasets to show that two approaches of lighting reproduction, matching illuminant spectra directly and matching material color appearance observed by one or more cameras or a human observer, yield the same LED selections. Our proposed optimal set of five LEDs includes red, green, and blue with narrow emission spectra, along with white and amber with broader spectra.

This study aims at explaining how to design multi-view prints that can show different images in different illumination conditions. A recent reflectance-transmittance optical model for recto-verso halftone prints is extended in order to fasten the calibration step and is used, according to an inversed approach, to design the rectoverso prints displaying the different images in their respective illumination modes. The good prediction accuracy of the model allows creating special effect prints, such as transformation of a binary image in one mode into a second binary image in the second mode, or the transformation of color image into a grey-level version, or the revelation of a message by texture contrast. Regarding the illumination conditions, simultaneous illumination of both sides of the print is allowed. The difficulty of designing such print comes from the fact that the images that are printed on the two sides of the paper are not the images that are displayed, and that the colors displayable in one mode depend on the colors wanted in the other mode. Since no general color management method for these kinds of prints is available, ad hoc methods are proposed for the different effects considered.

This paper analyzes the surface appearance of a textured fluorescent object. First, the bispectral radiance factor of the fluorescent object is decomposed into the fluorescent emission (luminescent) component and the reflection component, which are summarized as the Donaldson matrix. Second, the observed spectral images are described by a multiplication of two factors: one factor is spectral functions depending on wavelength and another is the weighting factors representing the surface texture. An algorithm is proposed to estimate the bispectral functions and the location weights from the spectral images observed under multiple illuminants. Third, the two textured images of the reflection component and the luminescent component are constructed using the estimates of the spectral function and the location weights. Also the surface appearances of the same fluorescent object under arbitrary illumination are constructed by combining the two component images.

The optical and visual characterization of translucent materials according to their shape and thickness is still a challenge for scientific research due to the difficulty to describe and predict in a simple manner the angular and spectral distributions of the reflected and transmitted light. In this paper, the light reflection and transmission properties of slightly scattering polymer sheets stacked with each other are studied. The light that is regularly reflected and transmitted by the material, propagated without scattering, as well as the light which is scattered out of the regular directions, are predicted using only a few measurements from a commercial reflectance/transmittance spectrophotometer and an extended two-flux model of the radiative transfer. The proposed methodology, validated by experiments, can be applied by laboratories equipped with an integrating sphere device which is usually used in the context of strongly diffusing rather than translucent materials. A discussion states the potential and the limitations of the proposed methodology.

In 2013 the European Metrology Research Program (EMRP) funded a 36 months research project, "Multidimensional Reflectometry for Industry, xD-Reflect", to investigate the macroscopic optical properties related to visual appearance of modern surfaces. During the three years duration of the project, over in August 2016, several visual experiments have been performed to investigate appearance of materials with goniochromatic and sparkling effects. Metal-flakes produce shiny effects whose definitions, quantities and metrological characterizations are still under development. This paper relates to the measurement and visual estimation of graininess and brightness perceived of metal flakes achromatic pigments materials. The subjective ranking on graininess and brightness of three different sample sets different for particles shape (silver dollar and corn-flakes) and dimension, were compared under similar viewing conditions on two commercial lighting booths, one based on LED lighting and one on fluorescent light, both reproducing CIE D65 illuminating conditions. The subjective rankings were compared with the graininess measured with a Byk-Mac instrument and the luminance measured with a luminancemeter in the experimental conditions inside both lighting booths. The performances of the two lighting cabinets and of the two different flake shapes were also compared. The results are useful both for shops lighting arrangements and industrial panelist investigations.

Orange peel is an important appearance quality factor that consists of an irregularity of a surface appearance that resembles the skin of an orange. Several measurement methods for evaluating orange peel have been proposed. However, the correlations of these methods with subjective evaluation scores are insufficient. The purpose of this paper is to develop a new measurement and evaluation method. The measurement system is composed of a spectral camera and lighting device for projecting an evaluation pattern on an object. An evaluation model using the frequency characteristics of the projected pattern image and human visual characteristics is proposed. The results show that the correspondence between the evaluation model values and subjective values is high. Because this method is based on visual inspection, it is expected to be suitable for a wide range of applications.