porous silicon samples were prepared by electrochemical etching method for different etching times. the structural properties of porous silicon (ps) samples were determined from the atomic force microscopy (afm) measurements. the surface mean root square roughness (σ rms) changes as function of porosity were studied, and the influence of etching time on porosity and roughness was studied too. u...

Since commercial image detectors, such as charge-coupled device (CCD) cameras, have a limited dynamic range, it is difficult to obtain images that really are unsaturated, as a result of which the reflectance parameters may be inaccurately estimated. To solve this problem, we describe a method to estimate reflectance parameters from saturated spectral images. We separate reflection data into dif...

Determining the compositional properties of surfaces in the environment is an important visual capacity. One such property is specular reflectance, which encompasses the range from matte to shiny surfaces. Visual estimation of specular reflectance can be informed by characteristic motion profiles; a surface with a specular reflectance that is difficult to determine while static can be confident...

All existing shape extraction techniques that are based on photometric measurements rely on assumed surface reflection properties. We propose a method for determining the shape of surfaces whose reflectance properties may vary from Lambertian to specular without prior knowledge of the relative strengths of the Lambertian and specular components of reflection. The object surface is illuminated u...

A novel stochastic Bayesian estimation method is introduced for the purpose of suppressing specular reflectance in endoscopic imagery, benefiting both computer aided and manual analysis of endoscopic data. The maximum diffuse chromaticity, which is necessary for the calculation of the specular reflectance, is estimated via Bayesian least-squares minimization, with the posterior probability of m...

We work on a Bayesian approach to the estimation of the specular component of a color image, based on the Dichromatic Reflection Model (DRM). The separation of diffuse and specular components is important for color image segmentation, to allow the segmentation algorithms to work on the best estimation of the reflectance of the scene. In this work we postulate a prior and likelihood energies tha...

The infiltration by atomic layer deposition of three-dimensional opal structures has been investigated as a means of fabricating photonic crystal phosphors. ZnS:Mn infiltrated and inverse opals have been demonstrated with filling fractions >95%. Characterization of these structures by scanning electron microscopy, specular reflectance, and photoluminescence is reported. Specular reflectance mea...

Estimating the illumination and the reflectance properties of an object surface from a few images is an important but challenging problem. The problem becomes even more challenging if we wish to deal with real-world objects that naturally have spatially inhomogeneous reflectance. In this paper, we derive a novel method for estimating the spatially varying specular reflectance properties of a su...

1 This paper provides an introduction to photometric methods for image-based 3D shape reconstruction and a survey of photometric stereo techniques. We begin with taxonomy of active and passive shape acquisition techniques. Then we describe the methodical background of photometric 3D reconstruction, define the canonical setting of photometric stereo (Lambertian surface reflectance, parallel inci...

Current reflectance models for glossy surfaces assume that the reflectance from such objects can be represented by a linear combination of specular and diffuse reflectance functions. This assumption is based on the physics of reflectance of smooth dielectric materials such as plastic and holds quite well for perfectly smooth convex dielectric objects such as billiard balls. In this paper, howev...