1. For use in a phase-shift time-of-flight (TOF) system that emits signals of optical energy and determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object and detected by an array of pixel photodetectors, a method to assign a measure of confidence to output signals detected by said photodetectors, the method including the following steps: (a) acquiring during a time frame from said photodetectors active brightness data and total brightness data; (b) storing a priori-determined at least one of upper and lower detectable levels of optical energy for at least some of said photodetectors; (c) comparing levels stored at step (b) with presently generated output signals from said at least some photodetectors to identify which, if any, of said photodetectors is presently operating other than in an acceptable dynamic range; and (d) characterizing Z depth information obtained by output from said at least some detectors as being at least one of questionable confidence and acceptable confidence.