Abstract: A method and optical system auxiliary input calibration arrangement accurately and reliably discriminate between a user generated image and a video source generated image, such as one produced by a computer. The calibration arrangement includes amplifier devices for increasing the strength of a video information signal indicative of the video generated image, and a user generated auxiliary input signal indicative of an auxiliary input light image, without increasing spurious ambient light signals. A discrimination circuit generates a detection signal whenever the amplified information signals are greater than a predetermined reference level signal. A microprocessor calculates the appropriate predetermined reference level signal based upon ambient lighting conditions, the strength of that portion of the information signal indicative of the video image, the type of optical system and the distance the optical system is disposed away from a viewing surface.

Abstract: A method and apparatus facilitates the alignment and light sensitivity adjustment of an optical computer input system, which includes a user generated light directed onto a screen bearing a computer generated image, to convey information to the computer interactively by the user, even in a darkened room. The system discriminates between the user generated image, and the computer generated image. Devices facilitate the proper alignment of the system with the screen, as well as proper light sensitivity adjustments.

Abstract: A method and apparatus facilitates the alignment and light sensitivity adjustment of an optical computer input system, which includes a user generated light directed onto a screen bearing a computer generated image, to convey information to the computer interactively by the user, even in a darkened room. The system discriminates between the user generated image, and the computer generated image. Devices facilitate the proper alignment of the system with the screen, as well as proper light sensitivity adjustments.