Abstract: A calibration utility 22 for electronically-generated images decouples tone scale and color corrections by completing tone scale and color balance corrections upon separate RGB image signals (representative of intensity) and hue and saturation corrections upon combinations of RGB signals (representative of chrominance). An operator adjusts tone scale controls 32 and color controles 34, which provide values for calibrating separate RGB tone scale look-up tables 49a, 49b, and 49c and a color matrix 48 in a printer 14. To decouple the corrections, the tone scale look-up tables 49a, 49b, 49c are adjusted until the brightness of a predetermined number of image levels is accurately rendered. If the resultant image signal contains coloration in neutral areas, the values in the particular look-up table(s) for the color(s) producing the color cast in the neutral areas is adjusted, thereby producing a neutrally-adjusted image signal substantially free of neutral coloration.

Abstract: A skip-field guard-bandless video tape recorder records and plays back adjacent tracks on a video tape with two closely adjacent heads of opposing head gap azimuth angles (to suppress cross-talk), only during alternate (odd) half-rotations of the head drum. Unavoidable cross-talk of synchronization pulses from adjacent tracks does not create visible interference or timing errors during playback by virtue of a special offset angle .theta..sub.1, between the adjacent recording heads, proportional to the linear offset distance between adjacent tracks. During playback, skipped fields are "filled-in" by a repetition of each recorded field through a second (duplicate) pair of closely adjacent heads of opposing azimuth positioned to retrace the recorded tracks during the other alternate (even) half-rotations of the head drum. An offset angle .theta..sub.2 between the two head pairs (i.e.

Abstract: A pair of oppositely-disposed stabilizer devices support opposed magnetic heads for interfacing with opposite sides of a rotating magnetic disk. Each stabilizer device includes a block with an opening through which the magnetic head protrudes for engagement with a respective side of the disk. A flat, circumferential air bearing surface on each block surrounds the opening adjacent the disk for generating coupling forces that deform the disk out of its nominal plane on opposite sides thereof and into intimate contact with the transducing gaps on the respective heads. The stabilizer devices are positioned in relation to separate radii depending from the center of the drive spindle so that a circumferential offset is established that permits substantially separate interaction of the air bearing surfaces with the disk.

Abstract: In a time division multiplex video reproducing apparatus, a dual purpose memory serves to (a) perform time compression for time division multiplexing and (b) perform as a variable delay line for time base error correction. Seemingly unavoidable conflicts in the allocation of memory space (between multiplexing operations and time base error correction operations) are eliminated by performing the time base error correction operations during a memory idle time inherent in the time division multiplexing process. As a result, time base error correction in this invention requires little additional hardware and no additional space in the memory beyond that required for time division multiplexing.

Abstract: A time division multiplex video tape recorder has a channel for receiving the main portion of an incoming video signal, comprising the luminance signal and horizontal synchronization pulse, and a separate channel for receiving the modulated sub-carrier portion of the video signal, comprising the chrominance signal. The luminance channel includes a signal processor for separating the luminance signal and horizontal synchronization pulse from one another. The signal processor removes the horizontal synchronization pulse from the luminance channel and inserts it into the chrominance channel. The luminance signal of each horizontal video line is time-compressed by itself into a first time segment, while the horizontal sync pulse and the chrominance signal of the same horizontal line are time-compressed together into a second time segment, the two segments being recorded serially within the space of one horizontal line scan period.

Abstract: A time division multiplex video recording system records every other one of the two chrominance signals (I and Q or R-Y and B-Y) of successive video fields and records the luminance signal (Y) of every field in separate time division segments. During odd fields, it records the luminance signal and the I chrominance signal of every horizontal line and during even fields it records the luminance signal with the Q chrominance signal of every horizontal line. During playback, a field store memory receives and stores the previously recorded chrominance signal of each field for repetition during the next to fill in for the unrecorded chrominance signal. In another embodiment, a helical scan four-head video playback system repeats every field during playback of the next field by playing back the adjacent tape tracks of both fields simultaneously, to fill in for the unrecorded chrominance signal (thereby eliminating the requirement for a field store memory).

Abstract: Timing in a time division multiplex video cassette recorder is improved and skew jump error is virtually eliminated by recording video signals with a superimposed pilot signal synchronized to--but having a frequency greater than--the incoming horizontal sync pulse frequency. During playback, a local pilot signal--similar to the previously recorded superimposed pilot signal--and a local horizontal sync signal control the de-multiplexing process and timing. The local pilot and horizontal sync signals are controlled by a three-tiered feedback timing control loop: a phase lock loop varies a local clock signal in order to correct very fine time differences between the recorded and local pilot signals; a digital loop changes the frequency ratio between the clock signal and the local pilot signal to correct larger time differences between the recorded and local horizontal sync pulse signals; and a look-ahead up/down counter counts and stores the net cumulative change in the pulse repetition frequency ratio.

Abstract: A peripheral memory controller controls a helical scan magnetic tape recorder so as to record and play back data files in parallel tracks on a magnetic tape. The tape is contained in a cassette having a magnetic disk fixably mounted on one reel of the cassette so that the movement of the tape and rotation of the disk are simultaneous. The peripheral memory controller refers to a file allocation table stored in one (or more) tracks on the disk, in order to correlate data file descriptions with track locations on the tape. A disk head rapidly scans the file allocation table disk track(s) within just one (or a few) revolutions of the disk while transmitting the contents of the table to the peripheral memory controller. The controller deduces therefrom the tape track location of a particular data file and commands the tape to be transported to that location in order to access that file.

Abstract: Method and apparatus for the processing of color video signals in which the two fields of a color video frame are compressed into a single field without appreciable loss of picture resolution and without image disturbance and degradation. The compressed signal may be recorded on a single track of a VCR and played back in a still-frame mode without picture jitter, color loss, or image degradation. According to the invention, first and second color video signals of a predetermined time period (such as a field period) are compressed into a time-division-multiplexed (TDM) signal of a single time period. The luminance components of the first and second signals are summed to produce a sum luminance signal and subtracted to produce a difference luminance signal, the sum signal having a greater bandwidth than the difference signal. A chrominance signal is produced which is a function of the chrominance components of the first and second signals.

Abstract: A camera includes a photographic film having a given film speed which decreases when the film is exposed to light which varies from a given illumination level. A camera shutter is controlled by a timing circuit adapted to produce an exposure which is adjusted to compensate for the decreased film speed.