On Facial Expression Recognition Benchmarks

Table 1

Systematic review questions.

Question number	Question	Solution
RQ1	What is the most used feature extraction method for facial expression classification?	Identify the trends and opportunities for feature selection techniques for facial expression classification
RQ2	What is the most employed feature selection or reduction technique for facial expression classification?	Examine the trends for dimensionality reduction of the extracted features for the classification of facial expressions
RQ3	What is the most dominant algorithm utilized for facial expression classification?	To review the algorithms deployed for classifying facial expressions into the basic emotions
RQ4	What is the most utilized database for facial expression classification?	Explore the kind of database used: either posed or spontaneous or 2D or 3D database for facial expression classification
RQ5	What is the most dominant validation method for facial expression classification?	To investigate the most employed technique in evaluating the classification as well as portioning the dataset into fractions