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# Method of Evaluating Chain Codes

IP.com Disclosure Number: IPCOM000045268D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 62K

IBM

## Related People

Baier, H: AUTHOR [+5]

## Abstract

There are different software methods for evaluating chain codes. For increased speed, it is necessary to implement some of these methods by hardware.

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Method of Evaluating Chain Codes

There are different software methods for evaluating chain codes. For increased speed, it is necessary to implement some of these methods by hardware.

Chain codes are direction-oriented representations of the contours of figures, with the definitions assumed being East equals 0, South equals 1, West equals 2, North equals 3 (Fig. 1).

Other directional definitions are also possible.

Example 1 Chain code: 0, 0, 0, 1, 1, 1, 2, 1, 2, 3, etc.

The elements of the chain code can be represented by 2 bits each.

The hardware implementation (Fig. 5) described below provides the following results in response to the chain code: 1. Number of edges of a figure. 2. Length data between these edges. 3. Direction of edges. Hardware Implementation.

The chain code is fed to the decoder in numbers (2-bit-parallel). The respective numbers are summed in counters 0, 1, 2 and 3. In a comparator, the count is compared with a minimum value. The outputs of the comparator (greater than equals GT or less than equals LE) are connected to a logic gate array, with the result being defined by logic operations.

The minimum value in the comparator determines the magnitude of the digitalization errors to be tested. Example 2.

If an edge is signalled, the counter with the highest count supplies length value of the edge. Subsequently, the counter is set to zero. Example 3.

If evaluation starts at an edge and if that edge is also to be detected, then evaluation must conti...