Abstract: A programmable variable screening circuit with memory for storing at each address location both a pixel screen value and the memory address of the screen value for the next pixel to be screened, and a control including a latch pair for separating data from each memory location addressed into a screen value for screening the pixel and an address for addressing the memory location for the next screen value.

Abstract: Process and apparatus for allowing a raster input scanner with scanning array to operate asynchronously in which timing of the fixed rate shift pulses which delineate the integration period of the array is changed to maintain the shift pulses in timed synchronization with a random integration signal.

Abstract: A raster input scanner in which a dither generator introduces a random error signal to artificially increase the calibration signal accuracy during calibration of the scanner.

Abstract: A programmable screening circuit with memory for storing at each address location both a pixel screen value and the memory address of the screen value for the next pixel to be screened, and a control including a latch pair for separating data from each memory location addressed into a screen value for screening the pixel and an address for addressing the memory location for the next screen value.

Abstract: A scanner with high intensity source beam, a modulator for modulating the source beam to provide a zero order beam and first order writing beam in response to an image signal input, a polygon for scanning the writing beam across a moving recording member to write images thereon, a sensor in the path of the zero order beam providing a first black beam intensity signal while scanning between pages and a second white beam intensity signal while the writing beam scans an image background area, a circuit for differencing the first and second beam intensity signals from one another to provide a composite intensity signal representing the intensity of the source beam, and a second circuit for differencing the composite beam intensity signal from an intensity setpoint signal to provide a correction signal for adjusting the rf power to the modulator to maintain a substantially constant writing beam intensity.In a second embodiment, the correction signal is determined by a successive approximation register.