Hello,
I just checked the solutions for the first exercises session, and I'm not sure to understand how the best threshold values are chosen in the first exercise. For the first image, I understood that the treshold are chosen such that, on the pixels intensity histogram, the thresholds separate the two intensity peaks. On the second image (brain) I understood that the threshold values are chosen as to separate all the black pixels (the peak on the histogram) from the rest. I'm not sure how they are chosen on the third image.
Thank you in advance for your answer!