Patent ID: 6341180
Filing Date: 2002-01-22
Classification: G02B,G06T

Abstract:
A device for determining a focus between an image sensor and an object comprising:an image sensor for receiving an image of the object and for generating an image signal from the image, the image signal having an image component and a noise component; a filter calculator for receiving the image signal and for generating a filtered image signal such that the noise component of the image signal has been reduced, the noise component being reduced by increasing energy contributions from parts of the image signal which contribute a relatively larger proportion to the image component than the noise component and by decreasing energy contribution from other parts of the image signal which contribute a relatively larger portion to the noise component than to the image component; an energy calculator for receiving the filtered image signal and determining an energy level of the filtered image signal; a controller for receiving the energy level and for generating a control signal in accordance with the energy level; and a positioning mechanism for receiving the control signal and performing a focus adjustment based on the control signal; wherein the filter calculator further comprises: a linear convoluter; and a filter selected from the group consisting of: a Wiener filter, a modified second order difference filter, and a bandpass filter.