Image processing apparatus
First Claim
1. An image processing apparatus for processing an image of a roadway, said image including a plurality of pixels, each pixel having a luminance representative of an intensity of reflected light from said roadway, wherein said roadway is exposed to and illuminated by a source of non-stroboscopic ambient light having a diurnal variation, said apparatus comprising:
- estimating means for estimating an intensity of said ambient light illuminating the roadway at a location of a pixel of attention;
means for outputting an image signal representative of a luminance of said pixel of attention;
reflectance calculating means for converting the luminance of said pixel of attention into a reflectance, wherein said reflectance is determined by dividing the luminance of said pixel of attention by said estimated intensity of said ambient light illuminating the roadway at the location of said pixel of attention;
digitizing means for binary-digitizing the reflectance of said pixel of attention by comparing the reflectance of said pixel of attention with a threshold value, and for outputting a digitized reflectance signal; and
boundary recognizing means for recognizing a boundary of said roadway, said boundary of said roadway being defined by regions having digitized reflectance signal values different from each other in the image.
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Abstract
The image processing apparatus comprises: a pixel train setting unit for setting a pixel train; a moving average calculating unit for estimating the intensity of light illuminating the object as a moving average of luminance of the pixel train; a reflectance calculating unit for converting the luminance of the pixel into reflectance, with the luminance of the pixel divided by the estimated intensity of light; a digitizing unit for digitizing the reflectance of the pixel; an edge detecting means for detecting an edge at which the luminance of the image changes sharply; and a comparing means for comparing the digitized reflectance signal with the edge signal to detect a boundary of regions having different luminance from each other, to eliminate it from the digitized reflectance signal for being a false edge.
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Citations
18 Claims
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1. An image processing apparatus for processing an image of a roadway, said image including a plurality of pixels, each pixel having a luminance representative of an intensity of reflected light from said roadway, wherein said roadway is exposed to and illuminated by a source of non-stroboscopic ambient light having a diurnal variation, said apparatus comprising:
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estimating means for estimating an intensity of said ambient light illuminating the roadway at a location of a pixel of attention; means for outputting an image signal representative of a luminance of said pixel of attention; reflectance calculating means for converting the luminance of said pixel of attention into a reflectance, wherein said reflectance is determined by dividing the luminance of said pixel of attention by said estimated intensity of said ambient light illuminating the roadway at the location of said pixel of attention; digitizing means for binary-digitizing the reflectance of said pixel of attention by comparing the reflectance of said pixel of attention with a threshold value, and for outputting a digitized reflectance signal; and boundary recognizing means for recognizing a boundary of said roadway, said boundary of said roadway being defined by regions having digitized reflectance signal values different from each other in the image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An image processing apparatus for processing a signal representing a video image of a roadway, said video image including a plurality of pixels, each pixel having a luminance representative of an intensity of light reflected from said roadway, wherein a plurality of said pixels are exposed to and illuminated by a source of non-stroboscopic ambient light having a diurnal variation in intensity, said apparatus comprising:
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a video camera for generating an image signal representing the luminance of each of a plurality of pixels located at a plurality of pixel locations within said video image; a reflectance determination circuit for receiving said image signal and converting the luminance of each of said plurality of pixels to a reflectance value, wherein said reflectance value of a selected pixel is determined by dividing the luminance of the selected pixel by a value representing the intensity of said ambient light at the location of the selected pixel; and a boundary detection circuit for generating a signal representative of a boundary between pixel locations having reflectance signal values different from each other, said boundary defining a boundary of said roadway.
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16. An image processing apparatus for processing a signal representing a video image of a roadway, said apparatus comprising:
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a video camera for generating an image signal representing a luminance of each of a plurality of pixels located respectively at a plurality of pixel locations within an image of said roadway; a processing unit for receiving said image signal and converting the luminance of each of said plurality of pixels to a reflectance value, wherein the reflectance value of a selected pixel is determined by dividing the luminance of the selected pixel by a value representing an intensity of non-stroboscopic ambient light illuminating said roadway at the location of the selected pixel, said non-stroboscopic ambient light having a diurnal variation; and a boundary detection circuit for generating a signal representative of a boundary between pixel locations having reflectance signal values different from each other, said boundary defining a boundary of said roadway. - View Dependent Claims (17)
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18. A machine implemented process for identifying a boundary of a roadway, wherein said roadway includes regions illuminated by varying amounts of non-stroboscopic ambient light, said process comprising the steps of:
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generating an image signal representing an image of said roadway, said image of said roadway comprising a plurality of pixels located respectively at a plurality of pixel locations; generating a luminance value for each of said pixels comprising said image of said roadway; converting each said luminance value to a reflectance value by dividing the luminance value of a selected pixel by an average luminance of said selected pixel and a predetermined number of adjacent pixels; and generating a signal representing a boundary of said roadway by identifying adjacent pixel locations having different reflectance values.
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Specification