Progress Made
My sole focus area this week was the Look Light traffic light detection algorithm. This image processing / pattern recognition based algorithm is based on the Hough transform, which returns the positions of circles of radii within a specified range as found within an input image.
My work was broken up into the following areas:
- Detecting circles in general
- It took no time to detect a sole circle in a picture of a single circle. Detecting circles got harder with multiple circles in the picture. I was surprised to learn that the Hough Transform sometimes misses a circle within a group of concentric circles. I learned to optimize Hough transform radii parameters to detect all circles in images with multiple circles.
- Detecting circles in traffic light images
- My learnings and parameterization of the Hough Transform for pictures of circles were transferred to use on images of traffic lights as well as traffic lights side-by-side (if you can imagine differently-facing traffic lights for perpendicular directions being hung right next to each other).
- Increasing accuracy in traffic light circle detection
- I found out that the Hough Transform, in certain lighting conditions, sometimes “detects” curved edges as part of a circle and therefore “detects” circles that aren’t in the image. I am currently trying to determine, through empirical means, how to isolate just the physical light within the traffic light. I am leveraging the fact that the light of interest is illuminated, meaning that the respective pixels are of higher intensity (aka I can use some kind of filtering / thresholding). This allows me to run the Hough Transform on the isolated light portion of an image.
Progress
Reasonable progress made towards having a robust look light detection algorithm, so I believe I’m still on track. 🙂
Deliverables for Next Week
- Main priority: Keep optimizing the look light algorithm. Figure out how to best filter/threshold the traffic light image to isolate the light. Then, reassess and fine tune the Hough Transform parameters as needed.