Patent ID: 7613329

Claim:
An apparatus for controlling a position of a screen pointer, the apparatus comprising: a light source for illuminating an imaging surface, thereby generating reflected images; and a navigation sensor for generating digital images based on the reflected images, detecting defective pixel locations in the digital images, and generating movement data based on the digital images that is indicative of relative motion between the imaging surface and the apparatus, the navigation sensor being configured to maintain an adaptive history for each pixel location in the digital images, wherein the adaptive history comprises a smooth frame that is updated based on pixel values of each of the generated digital images, and that changes relatively slowly compared to changes between successive ones of the digital images, the smooth frame including pixel locations that correspond to pixel locations of each of the generated digital images, and wherein the navigation sensor is configured to identify a pixel location as being a defective pixel location if an absolute value of a difference between a value of a pixel at the location in the digital images and a value of a corresponding pixel in the smooth frame is less than a threshold value for N consecutive digital images, where N represents an integer greater than one.