Method and system for evaluating brightness values in sensor images of image-evaluating adaptive cruise control systems, especially with respect to day/night distinction

Abstract

The invention proposes a method and an arrangement for evaluating sensor images of an image-evaluating environment recognition system on a carrier, in which, in order to distinguish the light conditions in the area of the image-evaluating environment recognition system with regard to day or night, at least the gain and/or the exposure time of the at least one image sensor detecting the environment is/are monitored, a profile of the gain and/or the exposure time against time with relatively high gain or relatively long exposure times characterizing night-time light conditions, and a profile of the gain and/or the exposure time with relatively low gain and/or relatively short exposure times characterizing daytime light conditions. The environment recognition system according to the invention can also be used to search the detected environment for bright objects, the headlights of another carrier being used as additional information, for example.

1 . A method for evaluating sensor images of an image-evaluating environment recognition system on a carrier having a driver assistance system, wherein the driver assistance system has a lane-keeping assistance system, the method comprising:
 monitoring at least one of a gain and an exposure time of the sensor images detecting the environment to distinguish light conditions in an area of the image-evaluating environment recognition system with regard to day or night,
 wherein a state recognition profile of the gain and/or the exposure time against time with relatively high gain or relatively long exposure times characterizes night-time light conditions, and the state recognition profile of the gain and/or the exposure time with relatively low gain and/or relatively short exposure times characterizes daytime light conditions. 
   
     
     
         2 . The method according to  claim 1 , wherein the profile is determined by carrying out an instantaneous daytime or night-time recognition process in regular cycles using one of the instantaneous gain and the instantaneous exposure time of the image sensor, and wherein the method further comprises storing a number of previous daytime or night-time recognition processes which represent the profile in addition to the current daytime or night-time recognition process, said number corresponding to a predefined period of time. 
     
     
         3 . The method according to  claim 1 , wherein, in the event of an inconclusive assignment to a daytime or a night-time state, a third setting is provided for the image sensor, wherein the third setting does not contribute to a conclusive statement of the daytime or the night-time state. 
     
     
         4 . The method according to  claim 3 , an average value of the state recognition profile is used to determine the third setting in order to determine a state lying between a daytime state and a night-time state, wherein the average value is formed proportional to the state recognition profile or with the aid of a lookup table. 
     
     
         5 . The method according to  claim 1 , wherein the environment detected using the environment recognition system is searched for bright objects which indicate switched-on headlights of another carrier, wherein the occurrence of bright objects is then used as additional information. 
     
     
         6 . The method according to  claim 5 , wherein additional information used for distinguishing the daytime or night-time state further comprises indication objects which are recognized in a detected environment, wherein indication objects appear different by day and night. 
     
     
         7 . The method according to  claim 6 , further comprising:
 determining wherein a frequency with which the bright objects and indication objects are found in the detected environment; and   establishing a connection between a night-time state and a predefined frequency of the occurrence of the bright and indication objects in an environment.   
     
     
         8 . An arrangement for evaluating sensor images of an image-evaluating environment recognition system on a carrier having a driver assistance system, wherein the image-evaluating environment recognition system comprises: an image sensor,
 an electronic camera which is fitted to a vehicle, wherein the vehicle is a carrier provided with a lane-keeping assistance system, wherein the camera is configured to continuously record the front area in a direction of travel of the vehicle on a roadway
 wherein the camera and the image sensor capture a sensor image constructed from pixels comprising brightness values and colour values 
   an evaluation unit configured to distinguish light conditions in an area of the image-evaluating environment recognition system with regard to day or night using a gain and/or an exposure time of the camera which records the environment.   
     
     
         9 . The arrangement according to  claim 8 , further comprising:
 signaling the evaluation unit, based on the determination of a daytime or a night-time state, to apply parameters and presettings used to set a video-based or image-based driving assistance system the daytime or night-time state.   
     
     
         10 . The arrangement according to  claim 9 , wherein a speed of the vehicle, is applied to the evaluation unit. 
     
     
         11 . A computer program product stored on a computer-usable medium, comprising computer-readable program instructions which, when the computer program product is executed on a microprocessor with associated storage means, cause said microprocessor or computer to carry out a method according to  claim 1 .