People normally use video cameras and high definition cameras mostly used to covering large gatherings. Though one can get good picture quality and images but no camera has a feature which can help to count the number of people in the gathering.
If a camera has face detection technology, it can detect number of faces in a crowd by zooming. It will reject the face once recognized thus avoiding double counting.
Digital Camera for Crowd Counting is a technology which many camera companies would want .This technology would be available on mobile phones once the same is integrated in cameras. This technology is different from face detection feature in digital cameras as this technology would cover and count at the same time.
Photo source Evil Erin