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EP0210554A2
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A method of windowing image data in a computer system
Assignee: International Business Machines Corp
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Filing: 1986-07-18
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Granted: —
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Expires: 2006-07-18
Abstract
Abstract In a method for rapid windowing of display information in a computer system image data is maintained in a hierarchical data tree structure. The complete image field (1), within which the image is defined, is divided into cells (7). The window is defined within this field and a field of possible interest (5) is defined around the window. Then, for each node in the tree, summary node data is computed which identifies those cells within the field of possible interest which are at least partially occupied by the part of the image defined at that node. By traversing the tree it is then possible to identify rapidly the image data to be windowed.
Inventors
- 👤 David Frederick Bantz
- 👤 Carlo John Evangelisti
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 17:01
CPC Classifications
G; G06; G06T; G06T15/00; G06T15/10; G06T15/40; G06T15/06; G09; G09G; G09G5/00; G09G5/14
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
191 words
A method of windowing image data in a computer system in which image data representing an image within an image field (1) is maintained in a hierarchical tree with the complete image being defined at the root node and sub-images of the complete image being defined at lower order nodes, the primitive images which make up the sub-images and the image being defined at the leaf nodes of the tree, the method comprising the steps of: dividing the image field into a plurality of cells (7); defining a window (3) which represents the area of the image field to be displayed; defining, around the window, a field of possible interest (5) which comprises at least one of the cells; computing, for at least one node of the tree, summary node data identifying those cells if any within the field of possible interest which are at least partially occupied by the part of the image defined at that node; traversing the tree to determine, using the summary node data, which of the primitive images need to be processed for display in the window; and processing and displaying primitive images within the window.
Claim 2
Independent Claim
191 words
A method of windowing image data in a computer system in which image data representing an image within an image field (1) is maintained in a hierarchical tree with the complete image being defined at the root node and sub-images of the complete image being defined at lower order nodes, the primitive images which make up the sub-images and the image being defined at the leaf nodes of the tree, the method comprising the steps of: dividing the image field into a plurality of cells (7); defining a window (3) which represents the area of the image field to be displayed; defining, around the window, a field of possible interest (5) which comprises at least one of the cells; computing, for at least one node of the tree, summary node data identifying those cells if any within the field of possible interest which are at least partially occupied by the part of the image defined at that node; traversing the tree to determine, using the summary node data, which of the primitive images need to be processed for display in the window; and processing and displaying primitive images within the window.
Claim 3
Dependent Claim
93 words
A method of claim 1 comprising the step of defining summary window data identifying those cells in the field of possible interest which are at least partially occupied by the window and wherein the step of determining which of the primitive images need to be processed for display in the window comprises the step of comparing the summary node data at a node with the summary window data to determine which cells, if any, in the area of interest contain both the window and that part of the image defined at the node.
Claim 4
Independent Claim
34 words
A method according to claims 1 or 2 wherein the summary data comprises one bit for each cell within the field of possible interest to provide a binary indication of which cells are occupied.
Claim 5
Independent Claim
60 words
A method according to any one of the preceding claims wherein the step of computing summary node data comprises computing the summary node data for the leaf nodes and, then computing the summary node data for successively higher order nodes up to and including the root node by ORing the summary node data of the lower order nodes connected thereto.
Claim 6
Dependent Claim
37 words
A method according to claim 4 wherein the ORing of the summary node data is achieved using a first stack for the temporary storage of summary node data being ORed and a second stack for node values.
Claim 7
Independent Claim
85 words
A method according to any one of the preceding claims which, on changing the position of the window the respect to the image field, comprise the steps of determining whether the new window lies within the field of interest and: if so, traversing the tree to using the existing summary node data; otherwise, determining a new field of interest around the new window and recomputing the summary node data for the nodes of the tree with respect to the cells of new field of interest.
Claim 8
Independent Claim
47 words
A method according to anyone of the preceding claims wherein the lower order nodes connected to a higher node are precessed if the summary node data for the higher order node indicates that a primitive image element may require processing otherwise said lower order nodes are skipped.
References Cited (Backward Citations)
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