Patent EP0656609A1 successfully refreshed from Google Patents.
EP0656609A1
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EP
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Image processing
Assignee: Philips Electronics UK Ltd
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Filing: 1994-11-28
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Granted: —
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Expires: 2014-11-28
Abstract
Abstract Texture mapping or video mapping is performed in such a way as to obtain perspectively correct images. In order to minimise computational overheads, a technique for deriving texture coordinate values (U,V) at each pixel of an image (A), based on the inverse of the depth coordinate (z) at that pixel is described. In order to avoid aliasing the technique is extended by the determination of texture gradient values (dU/dX, dU/dY, dV/dX, dV,dY) in the vertical and horizontal directions.
Inventors
- 👤 Jeremy Stuart Morris
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:29
CPC Classifications
G; G06; G06T; G06T15/00; G06T15/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
94 words
An image processing method for rendering a two dimensional image from three dimensional image data, wherein a polygon defined in three dimensional space is projected into two dimensional space and pixel values from a two dimensional image are mapped onto pixels within said projected two dimension polygon, characterised by the steps of: determining the inverse of the depth value and the product thereof with respective mapping image coordinate values at each of the vertices of the two dimensional image; and interpolating therefrom to determine pixel values along edges of the image and positions therein.
Claim 2
Dependent Claim
38 words
A method according to Claim 1, in which the projected two dimensional image is divided into a plurality of triangles, and the steps of value determination and interpolation are carried out for each of the triangles in turn.
Claim 3
Dependent Claim
24 words
A method according to Claim 2, in which the triangles are processed in the order of the greatest to the least depth coordinate value.
Claim 4
Dependent Claim
33 words
A method according to Claim 2, in which the image is divided such that each of the plurality of triangles has an edge extending parallel to an axis of the two dimensional space.
Claim 5
Dependent Claim
40 words
A method according to Claim 1, comprising the further step of deriving texture gradient values as the rate of change of one or more texture coordinates in either or both axis directions of the two dimensional space within the image.
Claim 6
Dependent Claim
29 words
A method according to Claim 5, comprising the step of selecting one from a plurality of available resolution levels in dependence on one or more derived texture gradient values.
Claim 7
Dependent Claim
14 words
A method according to Claim 1, wherein the step of interpolation comprises linear interpolation.
Claim 8
Dependent Claim
152 words
Image processing apparatus arranged to render a two dimensional image from three dimensional image data, such that a polygon defined in three dimensional space is projected into two dimensional space and pixel values from a two dimensional image are mapped onto pixels within the projected polygon characterised by: first storage means arranged to store the coordinates of the vertices of the polygon projected into two dimensional space, together with depth and mapping image coordinate values for each; calculation means arranged to derive the inverse of the depth value and the respective products thereof with the mapping image coordinate values for the vertices; second storage means arranged to receive and store the derived values from the calculation means; and processing means coupled to said first and second storage means and arranged to interpolate the derived values from the second storage means to determine pixel values along edges of the images and positions therein.
Claim 9
Dependent Claim
36 words
Apparatus according to Claim 8, operable to successively map a plurality of polygonal images, including means for determining which of a plurality of such images has the greatest depth coordinate value and mapping that image first.
Claim 10
Dependent Claim
57 words
Apparatus according to Claim 8, wherein said processing means is operable to determine, for each pixel and from the depth coordinate value and information stored in said first and second memory means, a texture gradient value as the rate of change of a texture coordinate in an axis direction of the two dimensional space within the image
References Cited (Backward Citations)
EP0447222A2
Cited
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