Patent ID: RE42899

Claim:
A method for measuring the relief of an object using a camera provided with an array of pixels, said method comprising the steps of: a) projecting a grid on a reference object; the grid being located at a first position relative to the camera and to the reference object; b) taking, with the camera, an image of the reference object illuminated by said projected grid; said image of the reference object having an intensity values value for each pixel of the reference object image ; c) repeating steps a) and b) at least two times with the grid being located each time at two different known positions relative to the camera and to the reference object to yield at least three intensity values for each pixel of the reference object image ; d) computing the a reference object phase for each pixel of the reference object image using three reference object intensity values selected from the at least three reference object intensity values for the corresponding pixel; e) projecting the grid on the object; the grid being located at said first position; f) taking with the camera an image of the object illuminated by said projected grid; said image of the object having an intensity values value for each pixel position of the object image ; g) repeating steps e) and f) at least two times with the grid being located each time at said two different known positions to yield at least three intensity values for each pixel of the object image ; h) computing the an object phase for each pixel position of the object image using three object intensity values selected from the at least three object intensity values for the corresponding pixel; and i) computing the a difference of height between the object and the reference object for each pixel using said reference object phase and said object phase for the corresponding pixel; and j) using said difference of heights height between the object and the reference object for each said pixel to determine the relief of the object ; wherein at least one of the reference object phase and the object phase is computed, in step d) or step h), for each pixel by selecting the three most advantageous intensity values from at least four intensity values .