Fast Argument Quantization [SP Tips&Tricks]

A quantized low-resolution argument of a complex number or two-dimensional vector is required in many digital signal processing algorithms. Examples include APSK code demodulation for which it may be used to evaluate the Voronoi diagram; low-level processing for many computer vision methods that exploit histograms of gradient sample arguments, e.g., SIFT and HOG; and phase tracking/frequency estimation for which it may be used as a low-cost phase approximation. Often, such quantized arguments will have to be computed many times and under real-time constraints. Therefore, efficient solutions to these calculations are of interest.