I have difficulties with calculating bounding-box recall and precision for a validation set that contains roughly 50/50 images with objects and images without objects.

As recall can’t be calculated for images without any objects, I use these images only for getting a better estimate of my precision:

precision = P_p * N_p / (N_p + N_n)

recall = R_p

where P_p, R_p are the precision and recall values for non-empty images, N_p is the number of predicted bounding boxes for non-empty images and N_n is the number of predicted bounding-boxes for empty images.

Do you see any issues with this?

Are there any papers available that address this issue?

This forum really needs LaTeX integration!