Methods and apparatus to count persons in a monitored environment are disclosed. An example apparatus to count the number of people in a monitored environment is described, which includes an image sensor having a plurality of pixels, a pseudorandom number generator to generate pseudorandom coordinates, a reader to read first pixel data generated by a first pixel of the image sensor at a first time, the first pixel corresponding to the pseudorandom coordinates, a comparator to compare the first pixel data with second pixel data generated by the first pixel at a second time different from the first time to generate a change value, and a counter configured to generate a count of persons based at least on the change value.