This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Quanterr. Plot of quantized signal and its error own Atropos Source Code no close all figure generate some nice looking signal then scale to cos pi cos pi cos pi cos pi min max min quantization bits xq floor xq xq xq xq error signal qerr xq plot subplot plot 'b' xq 'r' title 'Original and Quantized Signal' subplot