What is the threshold?
The threshold is a model parameter which adjusts the sensitivity of the model. Increasing the threshold will increase the sensitivity of the model, generating hits that better match your model. The higher the threshold value is, the more similar to the model an object has to be in order to be detected Lowering the threshold will lower the sensitivity increasing the amount of error. This can be useful when you have used a single model (a face for example) and want the system to respond even when the view is not identical to that of the model used.