What is CountEm?
CountEm is an open source software freely available under the Creative Commons 4.0 license. It has been developed by Javier González-Villa, Marcos Cruz , Domingo Gómez and Luis Manuel Cruz-Orive at the department of Mathematics, Statistics and Computer Science of the Universidad de Cantabria.
What can I do with CountEm?
CountEm offers efficient and design unbiased estimation of the number of particles (people, heads, animals, objects ...) in an image. CountEm also predicts the standard error of the number estimate. The relative standard error is small, typically 5-10%.
Can I use the CountEm software and database for free and for any purpose?
Yes, it is available under the Creative Commons 4.0 license, which only requires appropriate credit. In case you use the CountEm software or database for scientific purposes please cite the corresponding paper from section Publications. In other cases please mention that CountEm has been used and refer to the web: countem.unican.es
How do I choose the rotation angle?
The rotation angle is fixed and arbitrary. In order to reduce the variance, we recommend to avoid alignments between grid and population patterns (e.g. spectator rows).
How do I choose the grid parameters?
In order to maximize efficiency the sizes have to be chosen so that the number of non-empty quadrats is above 30 and the number of particles per quadrat around 2-5 approximately. This would imply counting between 100 and 200 total particles captured by the grid of quadrats.
I am choosing the same parameters as before but I get a different grid of quadrats. How is this possible?
The position of the grid of quadrats is uniform random. The parameters determine orientation, size and separation of the quadrats in the grid.
I am choosing the same parameters as before but I get a different result. How is this possible?
Since the position of the grid is random, every time we run CountEm we will generally obtain a different estimate.
¿What is meant by particle?
A particle is any person, animal or object which we would like to count in the image. If it is not entirely observable in the image, the observable fragment of it is regarded as a particle.
The image has low resolution and some particles are hard to distinguish…
CountEm is only able to estimate the particles that are unambigously distinguishable for counting in the chosen image.
How precise should visual estimations be?
A rough guess in a few seconds should be sufficient. CountEm will adjust the parameters later if needed.
Can I estimate the number of particles in multiple images in a single run?
Yes, multiple images can be loaded simultaneoulsy. Crop the images excluding empty regions to increase the precision ot the estimation.
¿How do I decide whether a particle is inside or outside a quadrat?
A particle is counted in a quadrat only if it has points in common with the quadrat but it does not hit the extended forbidden red line of the quadrat. In the following example only two birds would be counted, namely those marked with yellow arrows. Note that here we regarded a bird, or a clearly distinguishable fragment of it as a particle.
