A system and method for enhancing inspections using infrared cameras through in-field displays and operator-assisted performance calculations. A handheld infrared imaging system typically includes an infrared camera having a programmed computer (optionally with stored reference data from previous infrared or optical scans) and an interactive user interface suitable for displaying images and prompting response and accepting input from the infrared camera operator in the field during an inspection. The user interface may enable an operator to designate at least one thing of interest on a displayed infrared image; and the programmed computer uses a performance algorithm to estimate performance associated with the thing of interest such as one of the following: a dimensioned-measurement value or a thermal-property characteristic or an electrical-property characteristic or a cash value or a rate-of-change characteristic or an assessment of risk or danger. The programmed computer may extract information or parameters from previously measured data (either transferred down from the PC database or locally resident in the camera from previously stored measurements). The programmed computer may vary the way in which it displays new measurements, including live or continuously updated display, based on the information extracted from the stored data. Implementations may incorporate a device used for periodic measurements or an "online" device used for continuous or continuously updated monitoring. One or more of the parameters extracted from the IR image may be trended or otherwise adapted to provide an automated alert to the user regarding significant changes or important findings.