Editing Optical mouse (section)

=== Principle of operation ===
To understand how [[optical flow]] is used in optical mice, imagine two photographs of the same object except slightly offset from each other.  Place both photographs on a [[light table]] to make them transparent, and slide one across the other until their images line up.  The amount that the edges of one photograph overhang the other represents the offset between the images, and in the case of an optical computer mouse the distance it has moved.

Optical mice capture one thousand successive images or more per second.  Depending on how fast the mouse is moving, each image will be offset from the previous one by a fraction of a pixel or as many as several pixels.  Optical mice mathematically process these images using cross correlation to calculate how much each successive image is offset from the previous one.{{Citation needed|date=November 2022}} The output of the optical sensor is usually delta {{Code|X, Y}} coordinates. Some optical ICs allow to get image data as well. Mice usually embeds some kind of Image Acquisition System and [[Digital signal processor|DSP processors]] for fast data processing.

An optical mouse might use an image sensor having an 18 × 18 pixel array of monochromatic pixels. Its sensor would normally share the same [[Application-specific integrated circuit|ASIC]] as that used for storing and processing the images. One refinement would be accelerating the correlation process by using information from previous motions, and another refinement would be preventing deadbands when moving slowly by adding interpolation or frame-skipping.{{Citation needed|date=November 2022}}

The development of the modern optical mouse at Hewlett-Packard Co. was supported by a succession of related projects during the 1990s at HP Laboratories.  In 1992 William Holland was awarded US Patent 5,089,712 and John Ertel, William Holland, Kent Vincent, Rueiming Jamp, and Richard Baldwin were awarded US Patent 5,149,980 for measuring linear paper advance in a printer by correlating images of paper fibers.  Ross R. Allen, David Beard, Mark T. Smith, and Barclay J. Tullis were awarded US Patents 5,578,813 (1996) and 5,644,139 (1997) for 2-dimensional optical navigational (i.e., position measurement) principles based on detecting and correlating microscopic, inherent features of the surface over which the navigation sensor travelled, and using position measurements of each end of a linear (document) image sensor to reconstruct an image of the document.  This is the freehand scanning concept used in the HP CapShare 920 handheld scanner.  By describing an optical means that explicitly overcame the limitations of wheels, balls, and rollers used in contemporary computer mice, the optical mouse was anticipated. These patents formed the basis for US Patent 5,729,008 (1998) awarded to Travis N. Blalock, Richard A. Baumgartner, Thomas Hornak, Mark T. Smith, and Barclay J. Tullis, where surface feature image sensing, image processing, and image correlation was realized by an integrated circuit to produce a position measurement.  Improved precision of 2D optical navigation, needed for application of optical navigation to precise 2D measurement of media (paper) advance in HP DesignJet large format printers, was further refined in US Patent 6,195,475 awarded in 2001 to [[Raymond Beausoleil|Raymond G. Beausoleil]], Jr., and Ross R. Allen.