Fig. 1. Segment of a digital ray, defined by grid-intersection digitization (as calculated by the Bresenham algorithm [11]).

Fig. 2. Segments of lower and upper digital 4-rays, which follow borders of the upper and lower dichotomies, which are linearly separated by a ray.

Fig. 3. Two parallel lines γ₁ and γ₂ contain a 4-arc between them; is the main diagonal distance between the lines. Vector n is the normal to γ₁, and v is the unit vector along the main diagonal.

Fig. 4. A cellular straight segment.

Fig. 5. Five intersection points (left) for grid lines n=0,1,…,4, mapped into a spirograph (right).

Fig. 6. Right: the maximum error of β is 1 or 0.5, respectively for α=0 or α=0.5. Left: the maximum error of β as a function of the estimated α-value, for n=6 [23].

Fig. 7. Input example for algorithm CHW_1982a [18].

Fig. 8. DSS recognition algorithm CHW_1982a based on syntactic codes.

Fig. 9. Digitization polygon for u=0100100.

Fig. 10. Notations for algorithm K_1990 [48].

Fig. 11. Applications of algorithm K_1990 [45].