Method for determining the reflectance of an object and associated device
First Claim
1. A method for determining the reflectance of an object, the method comprising the following steps:
- illuminating the object using an outside illuminant having an unknown and variable illumination,emitting at least one flash of light illuminating the object, each flash of light being emitted by a source and having a known illumination in a wavelength range,collecting the wave reflected by the object to form at least one image on a sensor,obtaining an equation with several unknowns, the equation being obtained from formed images, the reflectance of the object and the illumination of the outside illuminant being two unknowns of the equation,solving the equation,the step for solving the equation comprisingcalculating solution points of the equation,interpolating points calculated by an interpolation function, andusing at least one of the following approximations to solve the equation;
a first approximation according to which each image is derived from the emission of a separate flash of light,a second approximation according to which the interpolation function determines the stability points of the equation, anda third approximation according to which the illumination of the outside illuminant at the moment of emission of a flash of light is equal to the illumination of the outside illuminant at a preceding moment.
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Abstract
Disclosed is a method for determining the reflectance of an object, the method including a step of solving an equation having several unknowns, the equation being obtained from formed images, the reflectance of the object and the illumination of the external light source being two unknowns of the equation. The step of solving the equation includes: calculating solution points of the equation, interpolating the calculated points by way of an interpolation function, and using at least one of the following approximations to solve the equation: a first approximation according to which each image is derived from the emission of a separate light flash, a second approximation according to which the interpolation function determines the stability points of the equation.
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Citations
13 Claims
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1. A method for determining the reflectance of an object, the method comprising the following steps:
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illuminating the object using an outside illuminant having an unknown and variable illumination, emitting at least one flash of light illuminating the object, each flash of light being emitted by a source and having a known illumination in a wavelength range, collecting the wave reflected by the object to form at least one image on a sensor, obtaining an equation with several unknowns, the equation being obtained from formed images, the reflectance of the object and the illumination of the outside illuminant being two unknowns of the equation, solving the equation, the step for solving the equation comprising calculating solution points of the equation, interpolating points calculated by an interpolation function, and using at least one of the following approximations to solve the equation; a first approximation according to which each image is derived from the emission of a separate flash of light, a second approximation according to which the interpolation function determines the stability points of the equation, and a third approximation according to which the illumination of the outside illuminant at the moment of emission of a flash of light is equal to the illumination of the outside illuminant at a preceding moment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A device for determining the reflectance of an object, the object being illuminated by an outside illuminant having an unknown and variable illumination, the device comprising:
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a source, able to emit at least one flash of light illuminating the object, each flash of light emitted by the source having a known illumination in a wavelength range, a sensor, able to collect the wave reflected by the object to form at least one image, a processing unit, able to carry out the following steps; obtaining an equation with several unknowns, the equation being obtained from formed images, the reflectance of the object and the illumination of the outside illuminant being two unknowns of the equation, solving the equation, the step for solving the equation comprising; calculating solution points of the equation, interpolating points calculated by an interpolation function, and using at least one of the following approximations to solve the equation; a first approximation according to which each image is derived from the emission of a separate flash of light, a second approximation according to which the interpolation function determines the stability points of the equation, and a third approximation according to which the illumination of the outside illuminant at the moment of emission of a flash of light is equal to the illumination of the outside illuminant at a preceding moment. - View Dependent Claims (11, 12, 13)
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Specification