Abstract: A method and apparatus for generating a video display from an independent controllable video source in synchronism with an external video signal for eliminating electromagnetic interference between closely positioned cathode ray tube display monitors, each display monitor being connected to display a corresponding one of the two video signals. The system eliminates the electromagnetic interference by forcing the vertical retrace functions in the closely positioned monitors to occur simultaneously. In one form the system includes apparatus for stripping a vertical sync signal from an externally generated video signal and for applying that vertical signal to a comparator for comparison against an internally generated vertical sync signal used to control the video presentation from the independent video source.

Abstract: In cases where the reference signal pulses supplied to one input of the phase detector of a phase-locked loop (PLL) may shift in phase significantly, the PLL may not be able to lock-in quickly enough to the apparent input pulse frequency change. In video monitor circuits where digital counters are clocked by the output frequency of the PLL, for example, the momentary loss of synchronism can cause horizontal scanning of the monitor screen to start too early or too late. A circuit is provided that lets the PLL make normal phase and frequency adjustments during a predetermined period during which counter reset is disabled. The circuit provides a window before and after this period during which counter reset is enabled. A reference pulse with a substantial phase error falls within the window. If three conditions are met, namely, the Reset Enable window exists, the reference pulse occurred within the window and the scan is near the bottom of the monitor screen, then a counter reset to zero signal is produced.

Abstract: Apparatus for reading out individual X-ray images recorded on a double-emulsion radiographic film or on separate films that were coincident when exposed simultaneously to a polyenergetic or broad X-ray photon energy spectrum beam emergent from a body and where an image corresponding to one obtained with a low energy part of the spectrum is formed on one film and an image corresponding to a higher energy part of the spectrum is formed on the other. One readout apparatus is for the case of two separate films which, after development, are illuminated from the back and optically scanned to derive analog signals representative of the intensities of spatially corresponding picture elements on each film. Another apparatus is for the case where the two images are on opposite sides of a film and are represented by alternate fine image information lines obtained by interposing a grid during the X-ray exposure. Another is for the case where a reflective layer is disposed between the film images during readout.

Abstract: A method of controlling a digital video processor in a digital fluorography system wherein the electronic components of the processor are variously configured to perform math functions and manipulations on digital image data obtained in connection with carrying out x-ray examination procedures and the images are displayed on a television monitor or recorded. A system controller sends a complete recipe for a procedure to the memory of a microprocessor based CPU that controls the video processor. The latter CPU interprets the instructions and effects configurations and reconfigurations in the data paths of the video processor during television vertical blanking intervals.

Abstract: Apparatus for applying a gamma correction to digital CT numbers at a selected level and within a window. A memory is loaded sequentially with the gamma correction lookup table. At the start a counter generates a sequence of addresses, in response to clock pulses. These are addresses to another memory. Simultaneously, a variable address generator addresses the gamma lookup table memory to effect transfer of the gamma correction data to the other memory (window-gamma lookup table) at locations that are represented by the ratio of the locations in the gamma lookup table to the address in the window-gamma table. To read out and produce an image, the window black value is subtracted from the stored CT numbers in sequence. The resulting differences constitute addresses to the window-gamma lookup table whose output is then the gamma corrected values for CT numbers in the window. This digitized data is converted to analog video signals for driving a television monitor that displays the image.

Abstract: The perception of raster lines on a television monitor is obscured by continuously and cyclically vertically shifting and presenting in successive frames the raster in successive upward positions and then in successive downward positions by incremental amounts, the total maximum vertical shift distance being less than the distance between original horizontal raster lines, thus giving the appearance of blending the information between original horizontal raster lines. Vertical raster deflection is accomplished by cyclically delaying the original, or normal, vertically sync pulses by amounts which incrementally increase to a maximum for producing a vertical frame rise less than the distance between original horizontal raster lines and decrementally decrease to no delay. A photographic camera capable of multiple frame exposure time is used to produce photographs of the video monitor without connections or operational dependence upon the television monitor system.

Abstract: A composite video signal waveform is fed through a video mixer and to a video monitor for displaying a raster scanned image on its screen. Signals are also fed through the mixer for causing a cursor having distinctive light intensity to be overlayed on the image. Programs for defining multiple cursors are stored in a readable memory. A microprocessor uses the programs for generating cursor parameters for each horizontal raster line and these are stored in a random access memory. A direct memory access controller responds to occurrence of each horizontal sync pulse by loading the cursor parameters for each corresponding raster line into counters which determine the starting point and end point of the cursor in that line or the width of the particular cursor line. During the interval representative of cursor line width, signals are fed through the mixer for altering the brightness intensity of the display.