Stream processing for fast and efficient rotated Haar-like features using rotated integral images

An extended set of Haar-like features for image sensors beyond the standard vertically and horizontally aligned Haar-like features and the 45° twisted Haar-like features are introduced. The extended rotated Haar-like features are based on the standard Haar-like features that have been rotated based on whole integer pixel-based rotations. These rotated feature values can also be calculated using rotated integral images which mean that they can be fast and efficiently calculated with just eight operations irrespective of the feature size. The integral image calculations can be offloaded to the graphical processing unit (GPU) using the stream processing paradigm. The integral image calculation on the GPU is seen to be faster than the traditional central processing unit implementation of the algorithm, for large image sizes, allowing more complex classifiers to be implemented in real-time.