Method and system for imaging an external scene by employing a custom image sensor
A method and system are provided to image an external scene by employing a custom image sensor. The custom image sensor may use a GRRB array to filter the images of oncoming and preceding vehicle taillights captured by a vehicle camera. The method and system may also calculate a GRRB color metric for use in the custom image sensor by performing interpolation on a number of color channels, summing the brightness values for each of the color channels interpolated, normalizing each of the brightness values, and converting the normalized brightness values from an RGB scale to a linear scale of non-red to red.
1. A method for imaging a scene external and forward of a controlled vehicle, comprising:
filtering light received from the scene with a color filter array operably coupled to an image sensor;
generating image data corresponding to the filtered light; and
analyzing the image data in a controller, the analyzing comprising:
obtaining a red brightness value, a green brightness value, and a blue brightness value of the filtered light;
mapping the red, green, and blue brightness values onto a color area of a color lane that intersects an RGB color cube;
determining a redness value of one or more specified points on the color area;
summing each redness value to determine a total redness value; and
comparing the total redness value to a threshold to determine if the filtered light is one of a headlamp and a taillight of another vehicle.
2. The method of claim 1 , wherein analyzing the image rises interpolating a number of color channels in an area surrounding a peak pixel to obtain the red brightness value, the green brightness value, and the blue brightness value.
3. The method of claim 2 , wherein analyzing the image data further comprises summing the red brightness value, the green brightness value, and the blue brightness value to obtain an overall brightness content of the light.
4. The method of claim 3 , wherein analyzing the image data further comprises normalizing the red brightness value, the green brightness value, and the blue brightness value to the overall brightness content of the light.
5. The method of claim 1 , wherein the color plane comprises a linear scale of non-red to red.
6. A method for imaging a scene external and forward of a controlled vehicle, comprising:
filtering light received from the scene with a GRRB filter array operably coupled to an image sensor;
generating image data corresponding to the filtered light; and
analyzing the image data in a controller, the analyzing comprising:
obtaining a red brightness value, a green brightness value, and a blue brightness value of the filtered light;
mapping the red, green, and blue brightness values onto a color plane that intersects an RGB color cube, wherein the color plane has a linear scale of non-red to red;
determining a redness value of one or more specified points on a color area of the color plane, wherein the redness value is based on a relationship between the red, green, and blue brightness values and an expected value of red;
summing each redness value to determine a total redness value; and
comparing the total redness value to a threshold to determine if the filtered light is one of a headlamp and a taillight of another vehicle.
7. The method of claim 6 , wherein analyzing the image data further comprises interpolating a number of color channels in an area surrounding a peak pixel to obtain the red brightness value, the green brightness value, and the blue brightness value.
8. The method of claim 7 , wherein analyzing the image data further comprises summing the red brightness value, the green brightness value, and the blue brightness value to obtain an overall brightness content of the light.
9. The method of claim 8 , wherein analyzing the image data further comprises normalizing the red brightness value, the green brightness value, and the blue brightness value to the overall brightness content of the light.
10. A system for imaging a scene external of a controlled vehicle, the system comprising:
an image sensor including a color filter array for receiving light from the scene and for generating image data representing the scene; and
a controller for analyzing the image data, the controller configured to:
obtain a red brightness value, a green brightness value, and a blue brightness value of the filtered light;
map the red, green, and blue brightness values onto a color area of a color plane that intersects an RGB color cube;
determine a redness value of one or more specified points on the color area;
sum each redness value to determine a total redness value; and
compare the total redness value to a threshold to determine if the filtered light is one of a headlamp and a taillight of another vehicle.
11. The method of claim 1 , wherein the color filter array comprises a GRRB filter array.
12. The method of claim 1 , wherein the color plane comprises an equilateral triangle.
13. The method of claim 1 , wherein analyzing the image data further comprises determining the redness value of a specified point on the color area by computing the following equation:
COLOR= R +(1− G )+(1− B ),
where COLOR is the redness value, R is a red value of the specified point, G is a green value of the specified point, and B is a blue value of the specified point.
14. The method of claim 6 , wherein the color plane comprises an equilateral triangle.
15. The method of claim 6 , wherein analyzing the image data further comprises determining the redness value of a specified point on the color area by computing the following equation:
COLOR= R +(1− G )+(1− B ),
where COLOR is the redness value, R is a red value of the specified point, G is a green value of the specified point, and B is a blue value of the specified point.
16. The system of claim 10 , wherein the color filter array comprises a GRRB filter array.
17. The system of claim 10 , wherein the color plane comprises a linear scale of non-red to red.
18. The system of claim 10 , wherein the controller normalizes the red brightness value, the green brightness value, and the blue brightness value to an overall brightness content of the light.
19. The system of claim 10 , wherein the color plane comprises an equilateral triangle.
20. The system of claim 10 , wherein the controller determines the redness value of a specified point on the color area by computing the following equation:
COLOR= R +(1− G )+(1− B ),
where COLOR is the redness value, R is a red value of the specified point, G is a green value of the specified point, and B is a blue value of the specified point.