Sorry for the (very) late reply, but it has come to my attention that I erroneously included the default WPIlib vision tutorial sample images in this project (which light the target in red) instead of the green-lit test images we actually used for tuning. I will upload the correct test images when I get onto the right laptop.
Of course, you can also re-tune the color segmentation algorithm to look for red instead of green
EDIT: I have uploaded some sample images that should work with the default tuning.