The seminal work by Viola-Jones had the most impact in face detection. It used Haar-Feature, which is fast to compute with the help of integral image method.
Is there a feature method that is more efficient (computationally) than Haar-Feature?
For example, for a $24 \times 24$ window, the computational complexity is more than $180,000$.
Is there any feature method which has the same efficiency (or better) as obtained by Viola-Jones but less expensive computational complexity-wise?