IMAGE PROCESSING SYSTEM
First Claim
1. An image processor arranged to receive an image signal representative of a scene including a reference object of a predetermined shape, the image processor being operableto identify the reference object from the image signal,to detect a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, andto estimate a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the luminance distribution across the surface of the reference object is detected for luminance above a threshold clipping level.
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Accused Products
Abstract
A computer graphics generation system combines video images of a scene captured by a camera with one or more rendered computer generated objects. The system comprises a camera which is arranged to generate an image signal representative of a scene including a reference object of a predetermined shape, and an image processor. The image processor is arranged in operation to identify the reference object from the image signal, to detect a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and to estimate a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the luminance distribution across the surface of the reference object is detected for luminance above a threshold clipping level. Accordingly a reduction in the “wobble” of the computer generated objects in the scene can be achieved and a more stable image provided from the image light direction estimation.
49 Citations
15 Claims
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1. An image processor arranged to receive an image signal representative of a scene including a reference object of a predetermined shape, the image processor being operable
to identify the reference object from the image signal, to detect a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and to estimate a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the luminance distribution across the surface of the reference object is detected for luminance above a threshold clipping level.
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4. A system for generating composite images comprising an image processor and a camera, the camera being operable to capture an image representative of a scene including a reference object of a predetermined shape and to communicate an information signal representative of the image to the image processor, the image processor being operable
to identify the reference object from the image signal, to detect a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, to estimate a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, the luminance distribution across the surface of the reference object being detected for luminance above a threshold clipping level, and to generate a composite image comprising image data captured by the camera combined with a rendering of a computer generated object, the computer generated object rendered in accordance with the estimated direction of light.
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6. A method of estimating a direction of light incident on a reference object of predetermined shape, comprising
identifying the reference object from a received image signal representative of a scene including the reference object, detecting a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and estimating a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the detection of the luminance distribution across the surface of the reference object is only detected for luminance above a threshold clipping level.
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9. A computer program having computer executable instructions, which when loaded on to a computer causes the computer to perform a method of estimating a direction of light incident on a reference object of predetermined shape, comprising
identifying the reference object from a received image signal representative of a scene including the reference object, detecting a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and estimating a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the detection of the luminance distribution across the surface of the reference object is only detected for luminance above a threshold clipping level.
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12. A computer graphics generation system for combining video images of a scene captured by a camera with one or more rendered computer generated objects, the system comprising
a camera which is arranged to generate an image signal representative of a scene including a reference object of a predetermined shape, and an image processor which is arranged in operation to identify the reference object from the image signal, to detect a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and to estimate a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the luminance distribution across the surface of the reference object is detected for luminance above a threshold clipping level.
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15. An apparatus for estimating a direction of light incident on a reference object of predetermined shape, the apparatus comprising
means for identifying the reference object from a received image signal representative of a scene including the reference object, means for detecting a luminance distribution across a surface of the reference object by estimating a luminance magnitude at a plurality of surface points on the surface of the reference object, and means for estimating a direction of light incident on the reference object derived from the detected luminance distribution across the surface of the reference object by calculating the average of a plurality of luminance vectors, each luminance vector corresponding to one of the surface points and comprising a luminance magnitude of the corresponding surface point and a luminance direction corresponding to a direction perpendicular to the surface at the corresponding surface point, wherein the detection of the luminance distribution across the surface of the reference object is only detected for luminance above a threshold clipping level.
Specification