Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1999-02-05
2001-10-16
Brier, Jeffery (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C345S440000
Reexamination Certificate
active
06304271
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system and method for rendering an image, and particularly to a system and method for rendering a cropped image in a zooming environment.
BACKGROUND OF THE INVENTION
With the advent of the desktop computer, manual manipulation of images has been replaced to a large extent by manipulation of data from which images may be reconstructed. An image may be scanned and the resulting data stored and manipulated by the computer operating as an image processing system. Various kinds of image processing systems employ image editing, such as cropping, or other image processing operations. A computer implemented image editor processes stored images in accordance with edit operations and stores the edited images electronically for later use or for use in other systems.
Electronic image editing may be performed on a conventional desk top computer implementing a graphical user interface. In respect to image cropping, a known method of electronically producing cropped images on a computer implementing a graphical user interface is typically accomplished by defining a crop region for an image, extrapolating destination information from the source image, and constructing the destination image from the extrapolated information. This method of cropping requires the image editor to recalculate the extrapolation each time the image is moved or zoomed, resulting in relatively long process times. There is a need, therefore, for providing more efficient image cropping functionality for use in a zooming graphical user interface.
SUMMARY OF THE INVENTION
This invention provides an improved system and method for image cropping in a zooming environment, where the crop region becomes an attribute of the image in the image's local coordinates. By making the crop region an attribute of the zooming object image, an extrapolation need not be calculated each time the image is zoomed or moved. For purposes of this discussion, the terms object and image are used interchangeably when discussing image cropping functionality. A view object is a module which contains zooming objects displayed on, for instance, a screen. The view and the objects in the view have associated transforms describing their local coordinate system. The transform translates the object's local coordinates to global coordinates. Each zooming object and view object is bounded by a bounding box, the smallest geometric shape that circumscribes the object, and the image and view do not exceed their bounding boxes. For a view object, the transform also ensures that the view is centered with respect to the view's bounding box.
In a zooming engine according to the invention, a clip stack, transform stack and event handler are provided. When a crop region is selected for an image, the image obtains its crop region from the event handler object in coordinates local to the object, which coordinates are independent of the view (hereafter “local coordinates”). Prior to rendering, the view and the image are pushed on the transform stack. The transform stack calculates a screen transform from the existing view transform and object transform and any requested change to the view (e.g., a new level of zoom). The transform stack provides a screen transform operable to transform local coordinates to display screen coordinates.
The image's crop region coordinates are transformed to display screen coordinates using the display screen transform provided by the transform stack. The resulting transformation provides the display coordinates for drawing the image's crop region, and these coordinates are pushed onto the clip stack. The display screen transform is next applied to the image's bounding box coordinates to provide display screen coordinates for the image's bounding box. The crop region screen coordinates are read from the clip stack and its intersection with the image's screen coordinates are determined. A renderer then paints the intersection on the display and a cropped image appears at the desired level of zoom.
Selection of the crop region is implemented by an event handler, which is preferably implemented as a software object. The event handler is responsive to user inputs, preferably inputs from a mouse. When a user implements a cropping function on a zooming object, for instance by clicking on the object, the object calls the handler. The handler is responsive to mouse movements until the user releases the mouse or, alternatively, clicks the mouse on the object a second time. The event handler defines a crop region on the object as a box having opposite corners located by the mouse clicks and returns the crop region coordinates to the object. These coordinates are local coordinates.
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Brier Jeffery
Lerner David Littenberg Krumholz & Mentlik LLP
Sony Corporation
Yang Ryan
LandOfFree
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