Method for road sign recognition
First Claim
1. A method for road sign recognition, in which images of a region surrounding the vehicle are acquired by a camera,image data of the camera are analyzed, wherein at least one image region that contains a potential road sign is determined,the image region that contains the potential road sign is submitted to a first classification unit that identifies the potential road sign, on the basis of at least one class-specific feature, as a road sign belonging to a particular class having the class-specific feature,characterized in thata brightness or a color intensity of a surface of the road sign is analyzed along radially extending scanning beams starting from a defined starting point within the surface of the road sign, in a brightness or color intensity analysis that comprises a one-dimensional gradient formation of brightness values or color intensity values of pixels of the image data along the scanning beams,potential contour points of an information-bearing part of the road sign are determined from results of the brightness or color intensity analysis,a limited region of the surface of the road sign is extracted as an information-bearing part of the road sign that includes all determined potential contour points, andthe extracted limited region is submitted to a second classification unit for semantic interpretation.
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Abstract
For recognizing road signs, a camera captures image data of the surroundings of a vehicle. The image data are analyzed to determine a region that contains a potential road sign. The image region is evaluated by a first classification unit to identify a road sign belonging to a particular class based on a recognized class-specific feature. Then, the brightness or color intensity of at least a portion of the road sign is analyzed along radially extending scanning beams, to determine potential contour points of an information-bearing part of the road sign, which is then extracted and semantically interpreted in a second classification unit to determine the information content thereof.
21 Citations
20 Claims
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1. A method for road sign recognition, in which images of a region surrounding the vehicle are acquired by a camera,
image data of the camera are analyzed, wherein at least one image region that contains a potential road sign is determined, the image region that contains the potential road sign is submitted to a first classification unit that identifies the potential road sign, on the basis of at least one class-specific feature, as a road sign belonging to a particular class having the class-specific feature, characterized in that a brightness or a color intensity of a surface of the road sign is analyzed along radially extending scanning beams starting from a defined starting point within the surface of the road sign, in a brightness or color intensity analysis that comprises a one-dimensional gradient formation of brightness values or color intensity values of pixels of the image data along the scanning beams, potential contour points of an information-bearing part of the road sign are determined from results of the brightness or color intensity analysis, a limited region of the surface of the road sign is extracted as an information-bearing part of the road sign that includes all determined potential contour points, and the extracted limited region is submitted to a second classification unit for semantic interpretation.
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15. A method for road sign recognition, in which images of a region surrounding the vehicle are acquired by a camera,
image data of the camera are analyzed, wherein at least one image region that contains a potential road sign is determined, the image region that contains the potential road sign is submitted to a first classification unit that identifies the potential road sign, on the basis of at least one class-specific feature, as a road sign belonging to a particular class having the class-specific feature, characterized in that a brightness or a color intensity of a surface of the road sign is analyzed along radially extending scanning beams starting from a defined starting point within the surface of the road sign, potential contour points of an information-bearing part of the road sign are determined from results of the brightness or color intensity analysis, a limited region of the surface of the road sign is extracted as an information-bearing part of the road sign that includes all determined potential contour points, and the extracted limited region is submitted to a second classification unit for semantic interpretation, wherein the brightness or color intensity analysis is performed from the starting point outward along the scanning beams, and wherein the limited region that is extracted as the information bearing part is a region of a bright-background road sign for which the potential contour points were determined as dark-to-bright transitions, or is a region of a dark-background road sign for which the potential contour points were determined as bright-to-dark transitions, respectively in the brightness or color intensity analysis.
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16. A method of automatically evaluating a road sign in a driver assistance system in a motor vehicle, comprising steps:
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a) with a camera capturing image data of surroundings of the motor vehicle including a road sign; b) in an image processing arrangement, analyzing the image data to thereby recognize that there is a road sign represented in the image data; c) in the image processing arrangement, after optionally pre-processing the image data, evaluating a brightness or a color intensity of selected pixels of the image data representing at least a portion of the road sign, wherein the selected pixels are located only along scanning beams that extend radially from a starting point within the road sign represented in the image data; d) in the image processing arrangement, from results of the evaluating in the step c), determining image contour transition points along the scanning beams and defining a limited region of the road sign represented in the image data, whereby the limited region is bounded by outermost ones and encompasses all of the image contour transition points; e) in the image processing arrangement, extracting a portion of the image data, which portion falls within the limited region, as an information-bearing part of the road sign represented in the image data; and f) at least one of;
(I) visually displaying the portion of the image data on a display device in the motor vehicle, and/or (ii) providing the portion of the image data to further processing. - View Dependent Claims (17, 18, 19, 20)
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Specification