Digital Figure Research Articles

マルチスケール曲率による図形輪郭の特徴抽出

A method is described to extract features of contour of a figure based on its curvature. For a digital figure, curvatures are approximated by using differences of contour tangential angles at two points apart from each other with an appropriate distance scale. In this method, a set of curvatures with various scales is calculated, and from the curvature changes with respect to the multiple scales, the features of the original contour, such as the locations and angles of vertices, are extracted. The view-field resolutions for the analysis of features of figures are determined automatically, for each figure and its parts. >

A contour characterization for multiply connected figures

The characterization of a digital figure in terms of the multiple pixels, i.e., the pixels placed where the contour selfinteracts, can provide useful shape cues. These pixels can satisfactorily be detected if a suitable definition of contour simplicity is available. Such a definition is given in this paper, for the case of multiply connected figures. The multiple pixels are those where the contour fails to be simple, and they can be identified by using 3 × 3 local operations.

A Width-Independent Fast Thinning Algorithm

The skeleton of a digital figure can often be regarded as a convenient alternative to the figure itself. It is useful both to diminish drastically the amount of data to be handled, and to simplify the computational procedures required for description and classification purposes. Thinning a digital figure down to its skeleton is a time-consuming process when conventional sequential computers are employed. The procedure we propose allows one to speed up the thinning transformation, and to get a well-shaped skeleton. After cleaning of the input picture has been performed, the pixels of the figure are labeled according to their distance from the background, and a set, whose pixels are symmetrically placed with respect to distinct contour parts of the figure, is found. This set is then given a linear structure by applying topology preserving removal operations. Finally, a pruning step, regarding branches not relevant in the framework of the problem domain, completes the process. The resulting skeleton is a labeled set of pixels which is shown to possess all the required properties, particularly those concerning connectedness, topology, and shape. Moreover, the original figure can almost completely be recovered by means of a reverse distance transformation. Only a fixed and small number of sequential passes through the picture is necessary to achieve the goal. The computational effort is rather modest, and the use of the proposed algorithm turns out to be more advantageous the greater the width of the figure to be thinned.

An approach to figure decomposition using width information

Decomposition methods are sometimes convenient for shape analysis. In these cases, a representation of the digital figure in terms of some of its subsets becomes available, and a structural description can then be derived. The correspondence between the shape of the figure and the structure of its medial line is considered as a starting point to develop a decomposition technique, using mainly the width information provided by the labeled medial line. An appropriate partition of the medial line indicates the sets of pixels from which the blocks necessary to find the constituent components are built. A merging phase accomplishes the last step of the process.

Pattern thinning by contour tracing

The possibility of applying thinning algorithms to digital figures not already nearly thin is discussed in the framework of using contour tracing to inspect the pixels currently candidates for removal. The proposed algorithm takes advantage of this approach both to reduce the computation time needed to obtain the skeleton and to perform contour analysis in order to find the contour regions to be represented by the skeleton branches. Since different contour descriptions can be found, various skeleton structures can alternatively be generated depending on the requirements of the problem domain. The skeleton found may also be regarded as a discrete version of that obtained by using the medial axis transformation.

A thinning algorithm based on prominence detection

Binary pictures are taken into account and an algorithm which transforms a digital figure into a set of 8-simple digital arcs and curves, by employing local sequential operations, il illustrated. The adopted procedure considers the removal of suitable contour elements of the given figure and it is repeated on every current set of 1-elements as long as the final thinned figure is obtained. The notion of local elongation is employed to find, at every step of the process, those contour regions which can be regarded as significant protrusions. Then such regions are detected before applying the removal operations, contributing hence to the isotropic behavior of the proposed thinning transformation. Further refinements of the algorithm are also discussed.

A condition for digital points removal

Removal operations play a crucial role in most algorithms which transform digital figures into stick-like ones. In this note, digital points that are candidates to deletion are examined and a necessary and sufficient condition for their removal is given.

Wage Indexation - The Australian Experience

Wage indexation, a process whereby "wages (or significant elements of them) are regularly adjusted to movements of a prices index" was introduced into Australia as a form of incomes policy. The perceived need for such a policy emanated from economic and political realities. Inflation, running at 2.4% per annum in 1969 gradually increased to 7.1% in 1972, the year in which Labour gained office. Thereafter it rapidly moved into double digit figures and by the end of 1974 was running at nearly 20% Cost push factors were seen by many as the key catalysts in bringing about this economic disequilibrium. This reflected poorly on the government's ability to control such costs, particularly labour costs which increased spectacularly. In the year ending July 1974 male award rates rose by a record 27.3% while female rates, propelled by the phasing in of equal pay, increased by 39.2%

Video display system for fetal and maternal monitoring.

Signals from different fetal and maternal monitoring equipment were combined in a video system. Analogue curves and digital figures were displayed on the same screen and included warning signals. Sweeps for different curves are selected individually. It is possible to show fast and slow changing parameters on the same screen. The system has great flexibility and signals from equipment from different manufacturers may be added easily.

A Measure for Circularity of Digital Figures

It is demonstrated that ?R/?R, where R is a random variable of the distance between the center of the figure to any part of its perimeter, is a good measure for the circularity of a digital figure.

Reduced to numbers

And so computer madness hits the Institute. With our 1973 subscription forms comes the news that we are ten digit figures, taking part in groups coded in Field 761 (but not Field 76D).