Polaroid Corporation

William R Wray

James L Burkhardt

Kenneth C Kiesel

A field of image information is processed with operations on a relatively coarse representation of the full field and with operations on a high resolution representation of only a portion of the full field. The partial results from operations on field portions may be formatted to yield a composite result for the full field. A photographic record of the image information may be read to provide the full-field representation and read again to provide the field-portion representation. This portion-by-portion processing of image information stored on a photographic record enables a computer with comparatively small memory capacity to execute relatively complex image processing tasks.

Method and apparatus for image processing with field portions

Improvements in a full resolution image A are effected with an economical use of computer processing equipment and time by determining a field of improvement functions derived from processing a coarse representation of the original full resolution image. The coarse representation B is subjected to lightness field analysis to obtain an improved coarse image C, from which a coarse improvement field D is extracted by subtracting the original coarse representation. To obtain a full resolution improvement field E, the coarse improvement function is smoothly expanded by interpolation to the dimensions of the full resolution image. By modifying the original full resolution image field A with the values of the full resolution improvement field E, an improved full resolution image is obtained.

Reconstitution of images

An oscillator unit having a charge storage device periodically rapidly charged through a small resistor and slowly discharged through a large resistor under control of a comparator for producing an oscillatory output and a switch actuatable by means of a frequency controlled zero-crossing multiplier to selectively discharge the storage device and thereby repeatedly resynchronize the oscillator unit with the frequency input to the multiplier.

Synchronizable oscillator

Audio signals with opposite relative phases are recorded on two tracks. A dual track head reproduces the signals from the two tracks and introduces another phase reversal of one signal relative to the other. Noise which was not present in the record circuit, but enters the system at the playback head, is out of phase in the signals which the playback head applies to the playback circuit. Combining the out-of-phase noise components of the two signals substantially cancels the noise.

Electronic gain and noise control for recording of analog information

A sound receiving system has an array of microphone elements for producing output signals in response to incident sound, and signal processing means for processing the output signals to provide the array with pre-selected directional acceptance and rejection characteristics. Such processing includes integrating the difference between the output signals of a pair of elements to produce an integrated signal, summing the outputs of the same or different pair of elements to obtain a sum signal, and combining the integrated signal with the sum signal. The spatial position of pairs of elements and their orientation permit closely spaced pairs of elements to exhibit a single highly directional characteristic, or two angularly related highly directional characteristics. Thus, an array of microphone elements clustered at essentially a point location can exhibit either monaural or stereophonic characteristics, depending upon the type of signal processing applied to their outputs. To minimize wind noise pickup, low frequency components of the integrated signal are suppressed to produce a filtered integrated signal, and high frequency components in the output signal of at least one of the elements are suppressed for producing a filtered output signal. The two filtered signals are added together to produce a resultant signal wherein only the higher frequency information signals will be directionally picked up and amplified.

Receiving system having pre-selected directional response

A recorder for the recording and the playback of analog information on a movable magnetic medium, e.g. a magnetic tape, has a limiter for reducing the gain of the record section in response to excessive input amplitudes, has a playback section that cancels noise which the transducer unit picks up, and has a muting circuit that diminishes playback gain during certain operations. The recorder applies the limiting function to the compressor portion of a dynamic compandor and applies the muting control to the expandor portion of the compandor. The noise cancellation introduces a relative phase reversal to noise present with different playback signals, and sums selected portions of those signals to cancel the noise.

Flutter in an audio signal recorded on a magnetic tape is reduced by sampling the audio at a rate determined by the frequency of a reference signal also recorded on the tape, reading the samples into respective cells of a memory, and reading out respective cells of the memory at a substantially constant rate that is independent of rapidly changing short duration variations in tape speed. The read-out rate is isolated from tape speed by introducing a time delay between the read-in and read-out of the same sample, the amount of the delay changing in accordance with differences in speed between the tape and a fixed reference. Changes in the delay between read-in and read-out of the same sample generate an error signal that is used to control the speed of the capstan motor that drives the tape past a transducer.

Flutter compensator with variable oscillator

In an apparatus for analog recording having a dynamic compressor for amplifying an analog input signal wherein the gain varies in response to an applied control signal, there is provided an improved limiter for providing a gain reducing influence to the applied control signal to control the gain to a generally single-valued function of the analog input signal for analog input signals having an amplitude within a select range.

A control system senses variations in the size of a buffer loop introduced in a magnetic recording tape or other flexible strip between a point of intermittent advance and a point of uniform advance. The control system maintains the size of the buffer loop at a selected measure by controlling the speed of the drive means which advances the tape uniformly. The control system has two response characteristics which cause the control system to react to variations in loop size either quickly or slowly depending on which response characteristic is chosen. During a first mode of operation, the faster response characteristic is chosen to establish the loop size quickly, while audio reproduction is muted. The control system then switches to a second mode of operation with the slower response characteristic which is compatible with audio reproduction. The control system employs an integrator responsive to an input signal indicative of loop size. The integrator output is a control signal which determines the speed of the drive mechanism for advancing the tape uniformly. In one embodiment, the signal indicative of loop size is provided by a circuit which produces an amplitude corresponding to the duty cycle of the output of a light detector which is illuminated via a path interrupted by the buffer loop. Preferably, the circuit includes a peak follower for the output of a gated integrator. The gated integrator provides a succession of rising output signals or 'ramps' which time the duration of a first level of the light detector output. The peak follower is reset before the end of each ramp.

Two speed loop control arrangement

An audio drive system having a pinch roller mounted in slightly trailing arrangement to the point of the initial engagement of the audio tape with the capstan so that, as the audio tape passes from the pinch roller and capstan, it is displaced from the original tape path to curl into a free loop and provide isolation between the continuous motion of the audio tape and the intermittent advancement for photographic motion.

Loop forming audio drive

A sound recording and reproducing system comprising a motion picture camera in which there is a synchronization system for recording segments of sound from a signal produced by a microphone associated with the camera as analog samples alternatively read into each of two analog shift registers in increments of samples corresponding to one frame time of the taking picture cycle. Means are provided for recording each such approximately timed sample sequence onto the film adjacent the frame being photographed during pulldown of the film in the camera. For playback, a projector is provided which comprises two analog shift registers each alternatively used for taking the samples recorded on the film for each frame for storage during pulldown, and then to transmit the stored samples through a filter to a loud-speaker for reproduction at a continuous rate during projection of the photographic images recorded on the film.

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Sudbury, MA, United States of America

William R Wray