Light source discriminating apparatus, a light source discriminating program, a vehicles detection apparatus, and a light control apparatus

• US 20100102990A1
• Filed: 10/16/2009
• Published: 04/29/2010
• Est. Priority Date: 10/17/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kamioka, Takahiro
• Granted Patent: US 8,242,934 B2
• Time in Patent Office: Days
• US Class Current: 340/942
• CPC Class Codes: G01J 1/18 using comparison with a reference electric value
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 2001/4247 for testing lamps or other light sources
• CPC Class Codes: G06V 10/758 Involving statistics of pixels or of feature values, e.g. histogram matching
• CPC Class Codes: G06V 20/584 of vehicle lights or traffic lights

Abstract

A light control system identifies in the processing that discriminates light sources in the acquired image as either luminous objects or reflective objects, each pixel obtained that constitutes the acquired image being classified into a plurality of groups according to the brightness of each pixel, and generates a histogram showing the relation of the brightness and the number of pixels of each group that are matched with each group. Then, when the number of pixels corresponding to the brightest group is less than the number of pixels corresponding to the other groups, the existence of the luminous object in the acquired image is determined, and when the number of pixels corresponding to the brighter group is more than the number of pixels corresponding to the other groups, the existence of the reflective object in the acquired image is determined.

Claims

1. A light source discriminating apparatus that discriminates between luminous objects and reflective objects comprising:

an acquisition means to acquire an image;

a frequency distribution generation means that groups pixels into one of a plurality of groups according to the brightness of each pixel from the acquired image, and generates a frequency distribution showing a relation between the brightness of each group and the number of pixels in each group;

a selection means that selects the brightness and number of pixels of each group from the plurality of groups in the frequency distribution; and

a discrimination determining means that determines whether there is any tendency for the number of pixels to decrease as the brightness increases in the frequency distribution for each group that the selection means selected, an existence of the luminous object is determined when the tendency is found, and an existence of the reflective object is determined when the tendency is not found.

2. A light source discriminating apparatus according to claim 1, wherein,

the selection means selects the group with the brightest pixel and the group with the most pixels in the frequency distribution,

the selection means determines that if a gradient showing the difference of the number of pixels within each group to the difference of the brightness in each group is less than a predetermined brightness gradient threshold, existence of the luminous object in the acquired image is determined, and when the gradient is more than the brightness gradient threshold, existence of the reflective object existing in the acquired image is established in each selected group.

3. A light source discriminating apparatus according to claim 1, wherein,

in the selection means, one or a plurality of groups (a 1st group) where the pixel that has the brightness more than a 1st threshold and one or a plurality of groups (a 2nd group) where the pixel that has the brightness more than a 2nd threshold, which is less than the 1st threshold, are selected from the frequency distribution,

whether the luminous object or the reflective object exists in the acquired image is determined by comparing the area ratio showing the ratio of the number of pixels of the 2nd group to the number of pixels of the 1st group with an area ratio threshold.

4. A light source discriminating apparatus according to claim 3, wherein,

in the selection means, the 1st threshold is configured to a value acquired by multiplying the brightest pixel by a 1st coefficient that is greater than 0 and less than 1, which is the brightness of the brightest pixel or the brightness of the brightest group of a pixel, and the 2nd threshold is configured to a value acquired by multiplying the brightest pixel by a 2nd coefficient that is greater than 0 and less than the 1st coefficient,

the 1st group and the 2nd group are selected according to the 1st and 2nd thresholds, respectively, in the frequency distribution.

5. A light source discriminating apparatus according to claim 1, wherein,

there is provided a light source detection means to detect a light source in the acquired image,

the frequency distribution generation means, the selection means, and the discrimination determining means perform each process for every light source detected by the light source detection means.

6. A light source discriminating apparatus according to claim 1,

there is provided a light source discriminating program for performing the function in a computer as each means to constitute the light source discriminating apparatus.

7. A vehicle detection apparatus that detects vehicles comprising:

a light source discriminating means that identifies whether a light source in an acquired image is a luminous object or a reflective object;

a characteristic determining means that determines whether the light source in the acquired image has a characteristics of the vehicle; and

a detection determining means determines that a vehicle is detected when the light source is decided to be a luminous object by the light source discriminating means and the light source has the characteristics of a vehicle as determined by the characteristic determining means;

wherein,

the light source discriminating means constitutes a light source discriminating apparatus.

8. A light source control apparatus equipped in vehicles that controls an illumination range of headlights in the vehicles comprising:

a vehicle detection means that detects the vehicles in an acquired image; and

a changing means dips the headlights only when the vehicles are detected by the vehicle detection means;

wherein,

the vehicle detection means constitutes a vehicle detection apparatus.