Patent ID: 7538815
Filing Date: 2009-05-26
Classification: G02B,H04N

Abstract:
1. A method for automatically focusing an image detector on an object, the method comprising: acquiring a first image of the object at a first focus level; applying a focus-measure function to the first image to obtain a first focus measure; moving from the first focus level towards a second focus level at a first focus-level adjustment velocity; calculating an amount of time to wait before acquiring a second image of the object at the second focus level; applying the focus-measure function to the second image to obtain a second focus measure; comparing the first and second focus measures; and moving from the second focus level to a third focus level at a second focus-level-adjustment velocity based on the comparing, wherein said comparing comprises: subtracting the second focus measure from the first focus measure and dividing the result by the change in focus level, and multiplying by a value representing the direction and magnitude of travel.