Recursive Representation and Progressive Display of Binary Objects for Efficient Network Browsing

✍ Scribed by I-Pin Chen; Zen Chen

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 713 KB
• Volume: 9
• Category: Article
• ISSN: 1047-3203
• DOI: 10.1006/jvci.1998.0401

✦ Synopsis

priate representation model of binary objects. In the existing facsimile system, a run-length representation of the When binary objects are browsed in a network environment, data transmission rate, progressive display capability, and view scanned data is used. This system has a nice data compresmodification under rotation, scaling, and/or translation (R/S/T) sion capability, but it cannot be used for progressive disare the major factors for selection of an appropriate representaplay. Also, it cannot generate a new view to reflect any tion model of binary objects. A new half-plane-based represen-R/S/T change. As far as progressive display capability is tation and display method for 2D binary objects is proposed. concerned, two types of object representation methods Within this modeling framework, a binary object approximated are commonly used: quadtree representation [1, 2, 3] and by a shape of a polygon can be represented as a collection transform coding [18]. These methods are different in their of half-planes defined over the edges of the polygon under data coding and progressive display mechanisms. The operations of union and intersection. The basic shape attributes quadtree method subdivides the image of the binary obof the object model are the slope and the y-intercept of the jects into successive levels of four blocks (or regions) until boundary line of the constituent half planes. In the progressive all pixels in the block have the same color (black or white)

display of the binary object our method adopts the quadtree or a specified level of resolution is reached. The transform block subdivision to divide the object image into hierarchical levels of detail (or resolution). Our method determines the color coding methods apply a set of basis images, each with a of a quadtree node based on the (angle, intercept) representation different block structure ranging from a low spatial freparameters. It is shown that the representation parameters at quency to a high spatial frequency, to model the object. The the parent node are recursively related to those at the child progressive display is achieved through successive inverse nodes. This recursive relation is crucial for deriving the color transformations using an increasing number of transform of the nodes for progressive object display. Lemmas for the coefficients. Figure 1 shows the results of progressive disnode color determination for an object expressed in the form play of a 1-D binary object by the quadtree representation of half-planes, a convex polygon, or a concave polygon are method and the Walsh transform method. In the quadtree derived step by step. Our method is generally better than many representation method, the shape of a block with a uniform existing methods in terms of data transmission rate, progressive color (black or white) remains the same at the successive display capability, and view modification under R/S/T varialevels of resolution while the block shape and color (i.e., tions. Simulation results are provided to illustrate the perforgray level) in the Walsh transform method vary drastically mance of our method.