Digital Image Processing

K. Natarajan ¹, K. Kuppusamy ²

Affiliations
1 Department of Computer Science, Thiagarajar College, Madurai-625009, TN, IN
2 Department of Computer Science and Engineering, Alagappa University, Karaikudi, TN, IN

Abstract

The paper presents a new simple clipping algorithm for 2D-polygon against rectangular windows. The polygon clipping process often involves a lot of intersection calculations and comparison. This paper propose a new 2D polygon clipping method, which makes only least number of edge and clipping region comparison and very few intersection calculations than any other traditional polygon clipping algorithms. The proposed algorithm is explained in step by step and compared with the Patrick-Gilles Maillot proposed method, and the Sutherland-Hodgeman algorithm and showing very less edge and clipping region comparison. The experimental results strongly support superiority of the proposed algorithm in comparison wise and it is theoretically and experimentally better than the conventional and Patrick-Gilles Maillot proposed method.

Keywords

Clipping Region, Clipped Point, Gentle Slope, Polygon Clipping, Sharp Slope.

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K. Natarajan ¹, K. Kuppusamy ²

Affiliations
1 Department of Computer Science, Thiagarajar College, Madurai – 625 009, TN, IN
2 Department of Computer Science and Engineering, Alagappa University, Karaikudi, TN, IN

Abstract

Polygon clipping process often involves a lot of intersection calculations and comparison. One way for improving the efficiency of a polygon clipping algorithm is to save the unnecessary intersection calculations demanded by traditional algorithm by rejecting totally the edges lies outside the window. This paper presents a new 2D polygon clipping method, based on an extension to the Sutherland- Hodgman polygon clipping method in which the efficiency is improved either by rejecting the edges lies outside a boundary or by avoiding the comparison of clipping boundaries against the sides of a polygon which neither totally nor partially crossing a polygon. The proposed algorithm neither remembers so-called entry/exit intersection points and nor about union points. After discussing two basic polygon clipping algorithms, a different approach is proposed, explaining the principles of a new algorithm and presenting it step by step. An example implementation of the algorithm is given along with some results. A comparison between the proposed method, the Patrick-Gilles Maillot polygon clipping algorithm, and the Sutherland-Hodgman algorithm is also given, showing very less comparison of edge and clipping region boundary than the Sutherland-Hodgman algorithm, and the Patrick-Gilles Maillot proposed method.

Keywords

Clipping Region, Line Intersection, Polygon Clipping, Window.

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K. Natarajan ¹, K. Kuppusamy ²

Affiliations
1 Department of Computer Science in Thiagarajar College, Madurai, IN
2 Department of Computer Science and Engineering in Alagappa University, Karaikudi, IN

Abstract

Polygon filling is a fundamental operation in computer graphics and image processing. The conventional polygon filling algorithms normally adopt an approach of scan line at a time generally called Scan_Line Algorithms typically uses many procedures and data structure of table (records) and fields. Using these procedures and data structures, the polygon filling process slows down because, many procedures which are involving to fill a polygon performing operation of sorting, reordering records and fields in a table and it makes these algorithm a time-consuming, tedious and very complex. This paper presents an enhanced 2D polygon filling method based on to the Scan-Line algorithm. After discussing simply about the Scan-Line filling algorithm and its procedures, a different approach is proposed and is explained step by step.

This proposed method, KN algorithm is fast, and uses simple data structure and less execution time, data reordering work and is independent of the polygon geometry. The experimental results strongly support superiority of the proposed algorithm in execution time wise and it is theoretically and experimentally better than the conventional algorithm.

Keywords

Concave Polygon, End Points, Polygon Filling, Vertex.

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K. Natarajan ¹, K. Kuppusamy ²

Affiliations
1 Department of Computer Science in Thiagarajar College, Madurai, IN
2 Department of Computer Science and Engineering in Alagappa University, Karaikudi, IN

Abstract

Polygon filling process often involves with lot of procedures which are repeatedly called by one another and making lot of calculations and data reordering works to fill a polygon. One way for improving the efficiency of a polygon filling algorithm is to save the unnecessary calculations and reordering works demanded by traditional algorithms either for rejecting some reordering works or for avoiding some sorting and calculations works. An adaptive filling algorithm is presented here to achieve this goal. The filling process of our new algorithm, NH algorithm, consists of five steps. Firstly, we read the value of edges of a polygon and avoiding the sorting of the sides which are normally required in a traditional algorithm. Secondly, we calculated all boundary points for each sides of a polygon between its maximum and minimum y value. Thirdly, we find all boundary points for each scan level. Fourthly, we sort all boundary points in the order of their minimum x values. And finally, even number of boundary points are selected and filled. Here, the data reordering analysis and experimental statistics between these two algorithms demonstrate the high efficiency of our new algorithm.

Keywords

Boundary Points, Concave Polygon, Polygon Filling, Vertex.

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