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US 7,444,006 B2Granted
Method of image qualification for optical navigation sensor
AssigneePixart Imaging Inc.
InventorChun-Huang Lin
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Abstract
An image qualification method. A motion detection method. An optical navigation sensor. Image qualification, requiring only a single image frame to determine if an image frame is qualified, proceeds in real time. On the basis of the image qualification method, a motion detection method that prevents erroneous flickers is also provided for use in an optical navigation sensor.
Claims22
A motion detection method for an optical navigation sensor, comprising steps of:
- capturing an image frame associated with the optical navigation sensor;
- distinguishing a qualified image frame from an unqualified image frame according to a quality prerequisite;
- providing a first counter to record incidence of qualified image frames, and a second counter to record incidence of unqualified image frames;
- when a first condition is met, proceeding motion detection and returning to the capturing step;
- and
- when a second condition is met, skipping the image frame and returning to the capturing step.
3 more elements
A real-time image qualification method for an optical navigation sensor, comprising steps of:
- capturing an image frame associated with the optical navigation sensor;
- evaluating a plurality of characteristics of the image frame to determine whether the image frame is qualified or unqualified;
- and
- outputting a result accordingly for motion detection, wherein the image frame is formatted in a number of lines, each comprising a plurality of pixels and the evaluating step comprises:
- scanning a line comprising a plurality of pixels;
- converting the brightness of pixels to a data curve;
- deriving a differential curve from the data curve;
- determining a point where the differential curve goes from positive to negative to be an up peak;
- and
- determining the point where the differential curve goes from negative to positive to be a down peak.
7 more elements
An optical navigation sensor comprising:
- an image capture device, for capturing an image frame;
- a quality control device, for assessing the quality of the image frame and outputting a result indicating whether the image frame is qualified or unqualified for motion detection;
- and
- a motion detector, for detecting motion of the optical navigation sensor according to the result output, wherein:
- the quality control device receives the image frame from the image capture device;
- the quality control device distinguishes a qualified image frame from an unqualified image frame according to a quality prerequisite;
- the quality control device provides a first counter to record incidence of the qualified image frames, and a second counter to record incidence of the unqualified image frames;
- and
- the quality control device outputs a result to the motion detector according to the image frame, the first counter and the second counter.
6 more elements
Dependencies are inferred from the claim text.