An automatic automatically-triggered digital video-imaging based code symbol reading system for use in point of sale (POS) environments, employing an adaptive control process involving the real-time analysis of the exposure quality of captured frames of digital image data and the real-time reconfiguration of system control parameters (SCPs) based on the results of such exposure quality analysis. By virtue of the present invention, the system enables the reliable reading of code symbols graphically represented in digital images, under demanding point-of-sale lighting conditions and other challenging environments.