Exterior environment recognition device

1. An exterior environment recognition device for recognizing the environment outside of a subject vehicle, on the basis of a color image captured by an onboard camera, the exterior environment recognition device comprising:

a specific object detection unit to detect a specific object on the basis of the color image;

a data retaining unit to associate and retain the specific object and a luminance range indicating the color of the specific object, and to associate and retain the specific object and the original luminance of the specific object;

a transparency reduction determination unit to compare a luminance of the color image of the specific object and a luminance range associated with the specific object, and to determine a reduction in transparency of a transparent body located in an image-capturing direction of the onboard camera;

a correction amount deriving unit to derive the amount of correction on the basis of a difference between luminance in the color image of the specific object and the original luminance associated with the specific object; and

a luminance correction unit to correct the luminance of the target portion of the color image on the basis of the amount of correction thus derived,

wherein the specific object detection unit detects the specific object on the basis of the corrected color image.

2. The exterior environment recognition device according to claim 1 , wherein

the correction amount deriving unit derives a basic amount of correction obtained by dividing the derived amount of correction by an exposure time of the color image; and

the luminance correction unit corrects the luminance of the target portion of the color image on the basis of the amount of correction obtained by multiplying the basic amount of correction by the exposure time of the color image of correction target.

3. The exterior environment recognition device according to claim 1 , wherein the correction amount deriving unit derives the amount of correction per divided region obtained by dividing the color image into multiple regions.

4. The exterior environment recognition device according to claim 2 , wherein the correction amount deriving unit derives the amount of correction per divided region obtained by dividing the color image into multiple regions.

5. The exterior environment recognition device according to claim 3 , wherein the correction amount deriving unit derives an amount of correction of a divided region for which the amount of correction is not derived, on the basis of an amount of correction of a divided region for which an amount of correction is derived.

6. The exterior environment recognition device according to claim 4 , wherein the correction amount deriving unit derives an amount of correction of a divided region for which the amount of correction is not derived, on the basis of an amount of correction of a divided region for which an amount of correction is derived.

7. The exterior environment recognition device according to claim 1 , wherein the correction amount deriving unit adopts again, as the amount of correction, a time average value of the amount of correction derived on the basis of a difference between luminance of the color image of the specific object and the original luminance associated with the specific object and the amount of correction previously derived in the same detection region or the same divided region.

8. The exterior environment recognition device according to claim 2 , wherein the correction amount deriving unit adopts again, as the amount of correction, a time average value of the amount of correction derived on the basis of a difference between luminance of the color image of the specific object and the original luminance associated with the specific object and the amount of correction previously derived in the same detection region or the same divided region.

9. The exterior environment recognition device according to claim 1 , wherein the specific object detection unit detects the specific object on the basis of temporal change of the luminance of the color image over time.

10. The exterior environment recognition device according to claim 2 , wherein the specific object detection unit detects the specific object on the basis of temporal change of the luminance of the color image over time.

11. The exterior environment recognition device according to claim 3 , wherein the specific object detection unit detects the specific object on the basis of temporal change of the luminance of the color image over time.

12. The exterior environment recognition device according to claim 3 , wherein the correction amount deriving unit adopts again, as the amount of correction, a time average value of the amount of correction derived on the basis of a difference between luminance of the color image of the specific object and the original luminance associated with the specific object and the amount of correction previously derived in the same detection region or the same divided region.

13. The exterior environment recognition device according to claim 4 , wherein the correction amount deriving unit adopts again, as the amount of correction, a time average value of the amount of correction derived on the basis of a difference between luminance of the color image of the specific object and the original luminance associated with the specific object and the amount of correction previously derived in the same detection region or the same divided region.

14. The exterior environment recognition device according to claim 4 , wherein the specific object detection unit detects the specific object on the basis of temporal change of the luminance of the color image over time.