Abstract: An automatic optical inspection system, for inspecting printed circuit boards and the like, employs so-called dimensional verification and pattern recognition techniques simultaneously. The printed circuit board is scanned by means of a CCD camera to produce a binarized image of the board. The image is stored and access provided to a set of picture elements arranged in a generally circular configuration and which are spaced apart by a dimension to be monitored by dimensional verification (DV) means. Access is also provided to a second set of picture elements arranged in a generally rectangular array of picture elements for the pattern recognition (PR) means, which uses template matching to determine their validity. The DV and PR outputs are weighted and clustered before a fault is signalled.

Abstract: A video codec is used to reduce the bandwidth of a video signal for storage and/or transmission. To transmit an uncoded quality color NTSC television signal is digitized form requires channel bandwidth typically 90-120 Mb/s for the signal in the composite format and 216 Mb/s for the signal in the component format. The proposed video codec achieves a reduction of the required transmission bandwidth by a factor of 2-3 by splitting the imput signal into two channels, a main and a complementary channel, and by applying different coding techniques in each. In the main channel the input signal is subsampled and DPCM encoded using a fixed-rate companded quantization, whereas VWL and block coding is used to encode the complementary channel carrying the interpolation error signal. This arrangement seeks to ensure high picture quality while being easily adaptable to different transmission rates and signal formats.

Abstract: When a video signal is encoded using differential pulse code modulation (DPCM) techniques, the frequency of occurrence of the various quantizer output or representative levels is non-uniform; usually, low levels occur more frequently than high levels, and this characteristic can be used to advantage by applying the DPCM output to a variable length encoder before transmission. The present invention increases this advantage by intentionally forcing the quantizer output to particular levels when doing so is not harmful to the picture fidelity. By so doing, the entropy of the encoded signal is reduced by as much as 25 percent.

Abstract: Video conferencing, wherein the outputs of a plurality of television cameras at one location are transmitted to a second location so that parties at the first location are perceived as present by parties at the second location, has received some attention directed toward bandwidth reduction. The subject invention relates to an improved video conferencing system for reducing bandwidth by advantageously applying temporal resolution and spatial reduction to a video picture provided by each camera. The temporal resolution of a picture from one or more of the cameras can be automatically adapted to a control signal, for example, to a speech level control signal so as to advantageously interleave and to give priority to a picture from one camera over a picture from other television cameras. The spatial reduction of each picture obtains by transmitting and displaying less than the total picture, illustratively the middle two-thirds of the picture from each camera.

Abstract: In PCM and DPCM systems, a Hadamard orthogonal transformation of picture element signals is known to offer a means for reducing the bit rate for transmission of the signals. The first Hadamard coefficient, called H.sub.1, equals the sum of the picture element signals. Accordingly, still further reduction in the transmission bit rate can be achieved by efficiently coding H.sub.1. The disclosed coder includes a control signal generator for providing a control signal corresponding to a predetermined function of the quantized Hadamard coefficient signals. Several illustrative arrangements are disclosed. In three arrangements, the respective control signals are employed to adaptively select one of a plurality of quantizers, the selected quantizer for coding H.sub.1. In a fourth arrangement, the control signal is employed to predict H.sub.1, the predictor control signal being thereafter used for coding H.sub.1.