Method for detecting repetitive surfaces in an optical mouse
View Patent ↗A repetitive surface detector includes an image capture device capturing an image. An autocorrelator receives the image and generates a signal indicative of a repetitive background of the image. A controller determines a maximum and minimum value in the auto-correlated signal. An adder determines the signed difference between the maximum and minimum value. A comparator compares the signed difference with a threshold and generates an output that indicates when the image includes a repetitive background.
1. A repetitive surface detector comprising:
an image capture device capturing an image;
an autocorrelator receiving the image and generating an auto-correlated signal indicative of a repetitive background of the image;
a controller, receiving the auto-correlated signal, generating a minimum value and a maximum value;
an adder, receiving the minimum and the maximum values, generating a difference;
a comparator, receiving the difference and a reference value, generating an output indicating when the image includes a repetitive background.
2. A repetitive surface detector, as in claim 1 , wherein the image capture device is a digital camera.
3. A repetitive surface detector, as in claim 1 , wherein the image capture device is an optical scanner.
4. An optical navigation device comprising:
a housing;
an image capture device, within the housing, generating an image signal; and
a microprocessor, receiving the image signal and generating a signal indicative of a surface;
wherein generating a signal indicative of a surface comprises:
auto-correlating the image signal;
obtaining a difference between a minimum value and a maximum value within the auto-correlated image signal; and
comparing the difference to a threshold value.
5. A method for detecting a repetitive surface comprising:
capturing an image;
auto-correlating the image;
obtaining a difference between a minimum value and a maximum value within the auto-correlated image; and
comparing the difference to a threshold value, when the difference is less than than the threshold value, a periodic surface has been detected.