Abstract: A method and apparatus is disclosed for adapting a low precision lead screw to perform in a high precision application by compensating for cyclical positioning errors that are produced by the lead screw. A stage assembly driven by a stepper motor is individually characterized and its inherent cyclical positioning error is stored in a memory device. The memory device is used to control a driving circuit that controls an operation of the stepper motor. The stepper motor is driven in a non-uniform manner that is complementary to a pattern of cyclical positioning errors in the stage assembly. As a consequence, a stage, driven by the lead screw, moves in a uniform manner. The system is disclosed in the context of a printer in which a receiver is driven at a uniform rate by an inexpensive low precision lead screw.

Abstract: A system and a method in which channel independent linear transfer functions or calibration curves for color devices such as printers, scanners and displays are individually created. The calibration curves are created using a low cost light intensity sensor. Scaling constants are determined and desired linear aim response curves are scaled together to maintain a desired color balance. The color saturation effects are also removed by scaling or normalizing to some maximum input drive level that does not saturate any of the colors. The characterization curves are rotated about the desired linear aim response curves to create compensation curves for each the characterization curves adapted to the particular device response characteristics. The dynamic range maximized, linearized, color balanced and saturation compensation curves are loaded into conversion tables which convert input values into the appropriate output values.

Abstract: An image capture and compositing apparatus for a photobooth (10) photographs a customer against a fixed color background (28), extracts the customer from that image and then inserts the extracted customer image into an arbitrary background image in such a manner that there are no noticeable artifacts between the inserted image and the background image and so that it appears that the subject was actually situated in the background scene when photographed. The imagery processing mechanism employed generates a pair of masks, one of which is associated with the foreground image and the other of which is associated with the background image. These masks are used to extract the subject (160) from an image of the subject against a reference color backdrop, to define what portion of the background image is to be blanked out and to controllably blend the border of the inserted subject image with the background image.

Abstract: A dual mode gen-lock system generates high frequency clocking pulses which are automatically synchronized to an external video signal. During the presence of color burst information in the external video signal, the clocking pulses are synchronized to the color burst. However in the absence of the color burst, the clocking pulses are synchronized to the horizontal sync pulses of the external video signal. This is accomplished by providing a phase locked loop which has an oscillator which free runs at the desired clock frequency, and which has a phase detector for comparing the phase difference between a selected portion of the PLL reference signal and a selected portion of either the color burst or horizontal sync pulses.

Abstract: A video timing system is provided for clocking an imaging sensor as well as for clocking a downstream video monitor and NTSC encoder. Due to signal processing delays between the sensor and the monitor/encoder, the first pixel is clocked out of the sensor prior to beginning the rasters of the monitor and encoders by a time period which is equal to the signal processing delay. In this manner, the first pixel out of the sensor is displayed at the beginning of the video rasters. In response to a video signal from an external source, the video monitor and NTSC timing is adjusted so as to be synchronous with the external source. Timing adjustment of the sensor is facilitated by the fact that the time period for early clocking of the sensor is unchanged whether or not the external video signal is present.