Determination procedure of the luminance of traffic signs and device for its embodiment

Abstract

The method of the invention comprises: obtaining a sequence of at least two images, with different levels of illumination; extracting the region containing the sign in the image; calculating the luminance values of the signs; and obtaining the difference in luminance of the sign corresponding to the two levels of illumination. The value obtained is the luminance of the sign ( 11 ) corresponding to an illumination equal to the difference between the illuminations, or additional illumination. This result is based on the additive property of luminance, according to which the luminance of a sign is the sum of the luminance produced by each source of illumination. A basic illumination device ( 5 ), an additional illumination device ( 7 ), at least one camera for taking images, and image recording, positioning and synchronism systems are required to implement the method.

1 .- 9 . (canceled) 
     
     
         10 . A luminance detection system connectable to a vehicle and operable while the vehicle is moving along a roadway, the luminance detection system comprising:
 a light source configured to illuminate a road marking positioned along the roadway, the light source being separate and distinct from a pair of headlights of the vehicle;   a first camera configured to obtain a first image, the first image including the road marking;   a second camera configured to obtain a second image, the second image including the road marking; and   a processor configured to:
 calculate a distance between the vehicle and the road marking based on the first image and the second image; 
 apply a luminance transform to convert pixel values to luminance levels representative of the road marking, wherein the pixel values are from at least one of: the first image and the second image; and 
 calculate a luminance value representative of a luminance of the road marking based on (i) the distance between the vehicle and the road marking and (ii) the luminance levels representative of the road marking. 
   
     
     
         11 . The luminance detection system of  claim 10 , wherein at least one of the first camera and the second camera is a color camera. 
     
     
         12 . The luminance detection system of  claim 10 , wherein the processor is configured to:
 extract pixel values representative of the road marking from the first image and the second image.   
     
     
         13 . The luminance detection system of  claim 10 , further comprising a geo-referenced positioning device configured to generate vehicle position data representative of a position of the vehicle along the roadway, wherein the processor is configured to calculate the distance between the vehicle and the road marking based on the vehicle position data. 
     
     
         14 . The luminance detection system of  claim 10 , wherein the light source is positioned at a front of the vehicle. 
     
     
         15 . The luminance detection system of  claim 10 , wherein the first camera and the second camera are positioned at a front of the vehicle.