This paper presents a new reflectance model for computer graphics, which accounts for the relative brightness of different materials and light sources in the same scene. The model describes the directional distribution of reflected light and the color shift that occurs as the reflectance changes with incidence angle. It includes methods for obtaining the spectral energy distribution of reflected light from specific real materials and for accurately reproducing the associated color. The model is applied to simulate metals and plastics, addressing the issue of why images rendered with previous models often appear plastic and how this can be avoided. The reflectance model is based on geometrical optics and is applicable to a broad range of materials, surface conditions, and lighting situations. It considers the intensity and spectral composition of reflected light, which are influenced by the intensity and size of light sources, the reflecting ability of the material, and the surface properties. The model is split into specular and diffuse components, with the specular component representing highlights and the diffuse component representing internal scattering or multiple surface reflections. The directional distribution of the reflected light is described using a microfacet model, where the angular spread of the specular component depends on the root mean square (rms) slope of the surface. The wavelength dependence of the reflectance is also considered, with the Beckmann distribution function accounting for the transition between physical and geometrical optics. The spectral composition of the reflected light is determined by multiplying the spectral energy distribution of the incident light by the reflectance spectrum of the surface. The model uses practical approximations to estimate the spectral and angular dependence of the reflectance, especially for nonmetals. To ensure realistic color reproduction, the model converts the spectral energy distribution of the reflected light to appropriate RGB values using trichromatic color reproduction laws. This involves calculating the XYZ tristimulus values and then converting them to RGB voltages, taking into account the monitor's nonlinearities and viewing conditions. The paper applies the reflectance model to simulate metals and plastics, demonstrating that a correct treatment of the specular component is crucial for achieving realistic nonplastic appearances. The results show that the specular component is typically the color of the material, not the light source, and that the ambient, diffuse, and specular components can have different colors if the material is nonhomogeneous.This paper presents a new reflectance model for computer graphics, which accounts for the relative brightness of different materials and light sources in the same scene. The model describes the directional distribution of reflected light and the color shift that occurs as the reflectance changes with incidence angle. It includes methods for obtaining the spectral energy distribution of reflected light from specific real materials and for accurately reproducing the associated color. The model is applied to simulate metals and plastics, addressing the issue of why images rendered with previous models often appear plastic and how this can be avoided. The reflectance model is based on geometrical optics and is applicable to a broad range of materials, surface conditions, and lighting situations. It considers the intensity and spectral composition of reflected light, which are influenced by the intensity and size of light sources, the reflecting ability of the material, and the surface properties. The model is split into specular and diffuse components, with the specular component representing highlights and the diffuse component representing internal scattering or multiple surface reflections. The directional distribution of the reflected light is described using a microfacet model, where the angular spread of the specular component depends on the root mean square (rms) slope of the surface. The wavelength dependence of the reflectance is also considered, with the Beckmann distribution function accounting for the transition between physical and geometrical optics. The spectral composition of the reflected light is determined by multiplying the spectral energy distribution of the incident light by the reflectance spectrum of the surface. The model uses practical approximations to estimate the spectral and angular dependence of the reflectance, especially for nonmetals. To ensure realistic color reproduction, the model converts the spectral energy distribution of the reflected light to appropriate RGB values using trichromatic color reproduction laws. This involves calculating the XYZ tristimulus values and then converting them to RGB voltages, taking into account the monitor's nonlinearities and viewing conditions. The paper applies the reflectance model to simulate metals and plastics, demonstrating that a correct treatment of the specular component is crucial for achieving realistic nonplastic appearances. The results show that the specular component is typically the color of the material, not the light source, and that the ambient, diffuse, and specular components can have different colors if the material is nonhomogeneous.