Nec Corporation

Fumio Ando

Takayuki Yokoyama

Kazuo Ichinokawa

An image signal encoding apparatus that receives a three primary color image signal composed of binary red, green and blue colors. A converter applies predetermined logical conversion to the three primary color image signal to produce first, second and third binary signals. When receiving a signal indicative of black, the converter generates first, second and third binary signals having a first level value. When receiving a signal indicative of white, the converter generates a first binary signal having a second level value and second and third binary signals having the first level value. The image signal decoding apparatus receives the first, second and third binary signals, and converts these binary signals to a three primary color image signal composed of a binary red, green and blue color signals. The reverse converter is operative when receiving three binary signals having a first level to produce a three primary color image signal indicative of black, and is operative when receiving the first binary signal having a second level and the second and third binary signals having the first level to produce another three primary color image signal indicative of white.

Image signal encoding/decoding apparatus and system

In an audiovisual communication, a first high fram rate video signal is derived from a motion image and converted to a low fram rate low resolution multiframe signal. A second high frame rate video signal is derived from an still image and converted to a single frame high resolution signal. Because of the low frame rates, the frequencies of the low and high resolution signals are within the range of frequencies of a telephone exchange line. A switching matrix is provided to sequentially couple both the low and high resolution signals to a transmission line in response to a mode select signal. The single frame high resolution signal is stored into a memory at the receiving end and repeatedly retrieved out of the memory into a display through the switching matrix.

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Tokyo, Japan

Fumio Ando