Method and an apparatus for coding/decoding telewriting signals
First Claim
1. A machine method for coding a line drawing, comprising the steps of:
- inputting a series of coordinate signals indicating the line drawing;
subtracting every two adjacent coordinate signals among said series of coordinate signals from each other so as to obtain a series of difference vector signals;
determining to which one of a plurality of predetermined zones each of said series of difference vector signals belongs;
determining relative pel positions of said series of difference vector signals in the determined zone; and
coding said determined zone and said relative pel positions within said determined zone independently of each other.
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Accused Products
Abstract
A difference vector indicating movement of a pen between two adjacent sampled points is divided into macro movement and micro movement components. The macro and micro components are coded independently of each other so as to provide effective coding. In the case of coding the difference vector, the magnitude of the difference vector is coded in accordance with the types of zones (zone number k) and relative pel address within the zone. In order to improve the coding efficiency, a zone number difference is used instead of the zone number. Furthermore, the direction of the difference vector is expressed by a quadrant which includes this difference vector. In order to further improve the coding efficiency, a quadrant number difference is used instead of the quadrant number.
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Citations
18 Claims
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1. A machine method for coding a line drawing, comprising the steps of:
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inputting a series of coordinate signals indicating the line drawing; subtracting every two adjacent coordinate signals among said series of coordinate signals from each other so as to obtain a series of difference vector signals; determining to which one of a plurality of predetermined zones each of said series of difference vector signals belongs; determining relative pel positions of said series of difference vector signals in the determined zone; and coding said determined zone and said relative pel positions within said determined zone independently of each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for coding a line drawing, comprising:
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an input terminal for receiving a series of coordinate signals indicating the line drawing; a differentiator for subtracting every two adjacent coordinate signals among said series of coordinate signals from each other so as to produce a series of difference vector signals; a quadrant circuit for determining a quadrant number of a quadrant of each of said series of difference vector signals; a quadrant differentiator for subtracting the quadrant numbers of the two adjacent difference vector signals from each other so as to produce a series of quadrant number difference signals; a zone circuit for sequentially determining a plurality of zones which include said series of difference vector signals in accordance with absolute values thereof; an area address circuit for sequentially determining unit areas which include said series of difference vector signals, said unit areas constituting said plurality of zones; a local address circuit for sequentially determining relative pel addresses which correspond to said series of difference vector signals; and an encoder for encoding the quadrant number difference signal, a zone number signal, an area address indicating the unit area corresponding thereto, and a local address indicating the relative pel address corresponding thereto.
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18. An apparatus for coding a line drawing, comprising:
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an input terminal for receiving a series of coordinate signals indicating the line drawing; a differentiator for subtracting every two adjacent coordinate signals among said series of coordinate signals from each other so as to produce a series of difference vector signals; a quadrant circuit for determining a quadrant number of a quadrant of each of said series of difference vector signals; a quadrant differentiator for subtracting the quadrant numbers of the two adjacent difference vector signals from each other so as to produce a series of quadrant number difference signals; a zone circuit for sequentially determining a plurality of zones which include said series of difference vector signals in accordance with absolute values thereof; a zone number differentiator for calculating a difference between the zone numbers of said zones which include the two adjacent difference vector signals so as to obtain a series of zone number difference signal; a circuit for generating relative addresses of the difference vector signals in the zone; and an encoder for encoding the quadrant number difference signal, the zone number difference signal and the relative address in the zone.
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Specification