The problem with detecting smiles

We must note at this point, that the problem of external validity (that is, the generalizability of our model) persists with a dataset like the smile detector. Given the restricted manner in which data has been collected, it would be unreasonable to expect our CNN to generalize well on other data. Firstly, the network is trained with low resolution input images. Moreover, it has only seen images of one smiling or frowning person in the same location each time. Feeding this network an image of, say, the managerial board of FIFA will not cause it to detect smiles however large and present they may be. We would need to readapt our approach. One way can be through applying the same transformations to the input image as done for the training data, by segmenting and resizing the input image per face. A better approach would be to gather more varied...