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Thickening Vectors on Display

IP.com Disclosure Number: IPCOM000086363D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Smith, PD: AUTHOR

Abstract

In a raster display, vectors or other lines are displayed as a series of dots. Sometimes it is desirable to thicken a vector from 1 picture element (pel) thick.

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Thickening Vectors on Display

In a raster display, vectors or other lines are displayed as a series of dots. Sometimes it is desirable to thicken a vector from 1 picture element (pel) thick.

Fig. 1 shows four typical vectors which are required to be thickened from their 1 pel thickness. If, for example, it is desired to thicken a vector to have a thickness of two pels, a second identical vector could be drawn alongside the existing vector. However, it would be difficult to determine which side of this two pel thick line is the true vector, and accordingly it is more desirable if vectors are thickened symmetrically on both sides.

Fig. 2 illustrates at A an algorithm for increasing the vector thickness. The symbol X represents an original point whereas the symbol T represents a point to be added. The thickened vector which is obtained using this algorithm is shown in view B, Fig. 2. It will be seen that although horizontal and sloping lines are thickened, vertical lines are not and thus the vector does not have a uniform thickness.

View C of Fig. 3 shows an improved algorithm in which 4 additional points are added around each existing point. The effect of this algorithm is shown in view D of Fig. 3. Not only do the thickened vectors have a more uniform thickness compared with that shown in view B, Fig. 2, but also the corners are rounded to give a more pleasing effect.

Fig. 4 shows some further algorithms which can be used to thicken vectors from 1 pel to 5 or 7 pe...