Patent Document ID: 9454263
Application ID: 14233127
Patent Status: 1

Claim One:
1. In a camera-based touch display that has a touch screen covering at least a portion of the touch display, a method of calibrating the touch display to account for geometric distortions caused at least by tolerances in placement and properties of a plurality of infrared cameras used for identifying objects touching a touch screen of the touch display, the method comprising: presenting one or more calibration patterns on the touch display; with each of at least two of the plurality of the infrared cameras; capturing a plurality of images of the calibration patterns or of a portion of the touch screen when a sheet of white or reflective material is arbitrarily placed on the touch screen and combining the plurality of the captured images to obtain for each of the at least two cameras a combined single-camera image having increased signal to noise ratio; the method further comprising: forming a touch screen image from the combined single camera images, the touch screen image covering at least a portion of the touch screen; determining geometric distortions of the touch screen image with relation to the presented one or more calibration patterns; calculating calibration parameters from the determined geometric distortions, and storing the calibration parameters for subsequent compensation of images taken by the plurality of infrared cameras, of objects touching the touch display or proximate thereof.