ORLANDO – It’s a question that vexes community organizers, police officers and journalists: How do you count how many people are at a large rally or demonstration?

Computer scientists at the University of Central Florida have an answer, and they can give it to you in a half hour with new software they unveiled last week.

UCF’s Center for Research in Computer Vision tested the software last month, using a demonstration in Barcelona over Catalonian independence.

The computer scientists estimated that 530,000 people were at the rally, well below the figures claimed by organizers.

The UCF software scanned aerial photographs of the crowd to reach the count.

Previously, to make a count, examiners would divide aerial photographs into sections and then count the number of heads per inch.