Disclosed in a method, a user interface and a system for use in determining shade of a patient's tooth, wherein a digital 3D representation including shape data and texture data for the tooth is obtained. A tooth shade value for at least one point on the tooth is determined based on the texture data of the corresponding point of the digital 3D representation and on known texture values of one or more reference tooth shade values.

A computer-implemented method for visualizing the appearances of at least two materials includes obtaining a first set of appearance attributes, the appearance attributes of the first set being associated with a first material, the first set of appearance attributes comprising measured appearance attributes, obtaining a second set of appearance attributes, the appearance attributes of the second set being associated with a second material; and obtaining a geometric model of at least one virtual object, the geometric model defining a three-dimensional macroscopic surface geometry of the virtual object. The invention is characterized by synthesizing a third set of appearance attributes from the first set of appearance attributes and the second set of appearance attributes and visualizing, using a display device, a scene comprising the at least one virtual object, using the third set of appearance attributes, a comparison set of appearance attributes and the geometric model, a first portion of the at least one virtual object being visualized using the third set of appearance attributes, and a second portion of the at least one virtual object being visualized using the comparison set of appearance attributes, to allow a direct a visual comparison of the first set of appearance attributes as modified by the second set of appearance attributes with the comparison set of appearance attributes.

A method of measuring the color of a surface may include a device positioned above the surface. The device may include an optical sensor and a display screen. The optical sensor measures visible light level reflected from the surface in a plurality of spectral channels. A plurality of patterns are sequentially displayed on the display screen. The optical sensor is used to measure light reflected by the surface during display of each pattern. A value is determined for the distance from the optical sensor to the illuminated region for a first local maximum of intensity of the measured light reflected by the surface. A location in a color space corresponding to a color of the surface or a reflectance spectrum of the surface is determined based on the visible light level in each spectral channel for the value of the distance corresponding to the first local maximum.

The optical device for measuring at least one of reflected light (BRDF) and transmitted light (BTDF) from a sample, in all spherical directions of space around the sample, for each spherical direction of incident light includes a light source, and a goniophotometer configured to measure at least one of: directions of the incident light in spherical coordinates, and directions of the reflected light in spherical coordinates. The device further includes a dispersive screen, and a multi-sensor imaging device. The goniophotometer includes a first articulated arm supporting the light source; and a second articulated arm supporting the sample or a sample holder.

Disclosed in a method, a user interface and a system for use in determining shade of a patient's tooth, wherein a digital 3D representation including shape data and texture data for the tooth is obtained. A tooth shade value for at least one point on the tooth is determined based on the texture data of the corresponding point of the digital 3D representation and on known texture values of one or more reference tooth shade values.

Apparatuses and methods for approximating a 5-angle color difference model are provided, where the 5-angle color difference model utilizes a 5-angle equation. In an exemplary embodiment, an apparatus includes a storage device for storing instructions and one or more processors configured to execute the instructions. The processor(s) are configured to receive 3-angle standard and test color measurements, and enter the 3-angle standard measurement into a neural network empirical model. The neural network empirical model includes a plurality of input nodes, a plurality of hidden nodes connected to the input nodes, and a plurality of output nodes connected to the hidden nodes. The neural network empirical model is configured to output 3-angle tolerance values, and to calculate a 3-angle color difference value using the 5-angle equation for at least one of the 3 color measurement angles using the 3-angle standard and test color measurements and the 3-angle tolerance values.

A device such as a stylus may have a color sensor. The color sensor may have a color sensing light detector having a plurality of photodetectors each of which measures light for a different respective color channel. The color sensor may also have a light emitter. The light emitter may have an adjustable light spectrum. The light spectrum may be adjusted during color sensing measurements using information such as ambient light color measurements made with a color ambient light sensor that has a plurality of photodetectors each of which measures light for a different respective color channel. An inertial measurement unit may be used to measure the angular orientation between the stylus and an external object during color measurements. Arrangements in which the light emitter is modulated during color sensing may also be used. Measurements from the stylus may be transmitted wirelessly to external equipment.

A system for measuring the spatial distribution of the spectral emission of a measurement zone of an object, comprises: a first objective; means for selecting a portion of an image formed by the first objective; a diaphragm; light-dispersing means located in the vicinity of the diaphragm and allowing the light coming from the selecting means to be dispersed; and a second objective placed between the selecting means and the diaphragm, interacting with the first objective so that the aperture of the diaphragm is optically conjugated with the measurement zone by the first and second objectives. The first objective forms an image on a predetermined Fourier surface on which each point corresponds to an emission direction of the object for one particular wavelength. The selecting means have a selection surface shaped depending on the predetermined. Fourier surface, and the selecting means are placed on the predetermined Fourier surface.

Disclosed herein is a computer-implemented method, a respective device, and a non-transitory computer-readable medium. The method includes: obtaining color values, texture values and digital images of a target coating, retrieving from a database one or more preliminary matching formulas based on the color and/or texture values obtained for the target coating, determining sparkle points within the respective obtained images and within the respective images associated with the one or more preliminary matching formulas, creating subimages of each sparkle point from the respective images, providing the created subimages to a convolutional neural network, the convolutional neural network being trained to correlate a respective subimage of a respective sparkle point with a pigment and/or pigment class, and determining, based on an output of the neural network, at least one of the one or more preliminary matching formulas as the formula(s) best matching the target coating.

Disclosed herein is a computer-implemented method for generating a coating formulation that yields a coating which is, to the eye of a human observer, identical or substantially similar in appearance to a target coating, as well as a device for performing the method.