Massachusetts Institute of Technology

Other

Electronics for Imaging Gmbh

Ecrm Incorporated

William F Schreiber

Edward H Adelson

Andrew Benjamin Lippman

Abraham A Bar

Donald E Troxel

Efraim Arazi

Aran N Netravali

Michael O Polley

An apparatus for encoding a television production signal for transmission, the television production signal including a first input signal carrying a first class of data and a second input signal carrying a second class of data, the second class data requiring a higher-quality transmission the first class data. For each word of the first input signal, the first stage generates N serial samples of the first output sample stream, each of the N serial samples being formed by a different combination of a set of more than one of the N samples of the each word. The second stage includes an input stage combining the second input signal stream with the first output sample stream to generate an intermediate input sample stream; a serial-to-parallel converter receiving the intermediate input sample stream and producing a second stream of words therefrom, each of the words of which being a parallel grouping of M successive samples of the intermediate input sample stream; a Discrete Fourier Transform (DFT) module producing a parallel output stream of words that is the discrete Fourier transform of the second word stream; and a parallel-to-series converter generating the FDM output signal from the parallel output stream of the DFT module.

Television transmission system using spread spectrum and orthogonal

A 2-stage SS (spread-spectrum) system for transmitting a coded TV signal, said coded signal consisting of first components requiring near-perfect transmission and second components for which somewhat imperfect transmission is acceptable, wherein a first SS process is used to determine the relative SNR of the recovered said second components, wherein the output of said first SS process is added to said first components to form combined signals, wherein a second SS process operates on said combined signals and is used to nullify the effects of multipath in the transmission channel and/or establish a multistep threshold, wherein the output of said second stage is modulated on a carrier, and wherein a transmitter receives said modulated carrier and generates a transmission signal therefrom.

Television transmission system using two stages of spead-spectrum

A noise-reduced method of transmitting a video signal including separating the video signal into a plurality of frequency subbands representing a corresponding plurality of subband images, each of which is made up of a corresponding array of blocks of samples; for a preselected one of the subband images, measuring the busyness of each of the blocks of that subband image; for the preselected subband image, assigning each of the blocks of that subband image to one of a plurality of groups, the plurality of groups including a group of more busy blocks and a group of less busy blocks; adaptively modulating the samples of the selected subband image by multiplying the selected subband image by a set of adaptive modulation factors, wherein a greater quantity of adaptive modulation factors is used for the blocks assigned to the group of more busy blocks as compared to the blocks assigned to the group of less busy blocks; and transmitting the adaptively modulated selected subband image along with the set of adaptive modulation factors corresponding thereto.

Methods of noise-reduced and bandwidth-reduced television transmission

The color correction system will enhance an operator's ability to edit and correct the appearance of a color image. This system is particularly useful in desk-top publishing applications. A reference image with an overall desired visual impression is displayed on a screen. This reference image is known to print in an acceptable fashion and give a desired visual impression. When the image to be corrected is modified in order to approximate the visual impression of a reference picture, then the picture to be corrected should print acceptably.

Color correction system employing reference pictures

A spread spectrum transmission system for transmitting a television signal, the transmission system including a module for dividing the television signal into a plurality of frequency components; a module for grouping at least some of the frequency components into a plurality of blocks, the grouping based upon the distance that each of the frequency components is from the origin in the frequency plane; a module for generating a plurality of spread spectrum signals, each of the spread spectrum signals being generated from a different one or more of the plurality of blocks; a module for combining more than one of the spread spectrum signals to form a combined signal; and a transmitter which receives the combined signal and generates a transmission signal therefrom.

Spread spectrum television transmission

The presence of random noise, interference, multipath, and imperfect frequency response in terrestrial broadcasting channels, and of pervasive low-level reflections in cable systems, degrades the quality of television reception. These effects tend to reduce the difference in quality between that of NTSC and that of various advanced television systems, as actually delivered to the home via such channels. Several methods are disclosed for dealing with these effects, and thus to preserve the improved quality made possible by currently proposed EDTV and HDTV systems. Automatic channel equalization is used for first-order correction of multipath and frequency distortion. A scrambling method is described that transforms all remaining degradations to additive random noise, which, for a given noise power, is of minimum visibility. Random noise, whether additive or produced by scrambling of other defects, is suppressed by adaptive modulation. If the channel SNR is high enough, some digital data can be transmitted in addition to the analog data by a method called 'data under'. The methods are applied to a receiver-compatible system that utilizes a very low-power 3-MHz augmentation channel as well as to a bandwidth-efficient 6-MHz system that is not receiver compatible. One version of the latter system can be operated at such low SNR that it may be possible to utilize the taboo channels.

Reliable television transmission through analog channels

A receiver-compatible EDTV system wherein enhancement information is adaptively modulated to suppress channel noise and is transmitted outside the usable picture area of a receiver compatible signal of the receiver compatible EDTV system.

Definition television systems

A television encoder for generating a receiver-compatible signal from a production video signal containing enhancement information which cannot be displayed on a standard receiver, the receiver-compatible signal being compatible with the standard receiver, the encoder including a filter bank for dividing the video signal into at least two groups of spatial frequency components including a first group and a second group, the first group containing members which when combined together form a standard video signal which is displayed by the standard receiver and the second group containing the enhancement information; a quantizer for quantizing at least one member of the first group; a combiner for adding at least one member of the second group to a quantized member of the first group to produce a modified first group; and a synthesizer for combining the members of the modified first group to generate the receiver-compatible signal.

Receiver-compatible enhanced definition television system

A high-definition television system in which a production signal is spatiotemporally filtered to remove frequency components and remaining components are transmitted over a channel. In various aspects, the filter produces a generally diamond-shaped frequency response in each of the spatial and spatiotemporal planes; the components selected for transmission are selected in accordance with the amount of motion in the image; the remaining components of image data are transmitted using double-sideband quadrature modulation; a high frequency component of the production signal shares the channel with additional data; and when the image data is transmitted using double-sideband quadrature modulation, baseband signals are derived from closely related areas of the image.

High definition television system

Improved effifiency of frequency-modulated (FM) transmission of signals through analog channels, i.e., achievement of a higher bandwidth and/or signal-to-noise ratio (SNR) in the received signal for a given channel bandwidth and channel carrier-to-noise ratio (CNR), is accomplished by adaptive adjustment of the modulation index in such a manner that the spectrum of the channel signal more nearly occupies the entire channel more of the time than it would otherwise. Data is transmitted, along with the signal, to enable the receiver to calculate the modulation index at each instant so that the signal can be properly demodulated. The invention has application to FM transmission of signals representing visual image or other information, such as sound, for which human perception of noise is greatest in areas of low amplitude and/or frequency and reduced in and immediately adjacent to areas of high amplitude and/or frequency.

Transmission of signals through analog channels using adaptive frequency

A system for reproducing a color original in a medium using a selected multiplicity of reproduction colorants, comprising: a scanner for producing from said color original a train of appearance signals dependent on at least three color values of said original; aesthetic correction circuitry for introducing aesthetically desired alteration into said appearance signals to produce modified appearance signals; and colorant selection mechanism for receiving said modified appearance signals and for selecting corresponding reproduction signals representing values of said reproduction colorants to produce in said medium a color match of said modified appearance signals.

Color reproduction system

Processing of digitally-coded pictures to improve perceived quality without increasing transmission channel capacity, featuring dividing the video signal into a low, middle and high frequency signals (16, 26), finely quantizing the low frequency signal (18), adding pseudo-random noise (33) to the middle frequency signal prior to quantizing (28), enhancing (36) and adding pseudo-random noise (48) prior to coarsely quantizing (50) the high frequency signal. The pseudo-random signals are subtracted (37, 52) from the respective signals at the receiver.

Image coding

Improvements in apparatus for making a halftone reproduction of an original document, of the type having an optical system comprising a source of light and a deflecting member for providing deflecting scanning and recording beams, a drive for providing relative motion between the original document and the scanning beam in a direction transverse to the direction of deflection thereof so that the scanning beam will trace a succession of scan lines across the document respectively during a succession of scanning cycles, an electro-optical pickup operative during each scanning cycle to detect the light from the scanning beam after it has impinged upon the document and to thereby provide an electrical output representative of the tone density (including any variation thereof) of the document along the scan line traced during that scanning cycle, video circuitry connected to the pickup for converting the electrical output into a video signal, a source of a succession of dot reference signals representative of the desired halftone screening pattern, output circuitry responsive to the reference and video signals to repeatedly compare the reference signals corresponding to the various cells of the halftone screening pattern with successive samples of the video signal and to generate halftone recording signals in accordance with the results of the comparison, a modulator in the optical system responsive to the output circuitry and operative during a succession of recording cycles to modulate the recording beam in accordance with the halftone recording signals, and a drive for providing relative motion between photosensitive output stock and the modulated recording beam in a direction transverse to the direction of deflection thereof so that the recording beam will trace a succession of record lines across the output stock respectively during the succession of recording cycles to record black and white dots in the cells of the halftone screening pattern.

Growing community of inventors

Cambridge, MA, United States of America

William F Schreiber