ABSTRACT
This chapter focuses on how to format thermal images to maximize the qualitative visual information available to the human eye, and how to perform quantitative thermal measurements on the image guided by these qualitative findings. The three types of thermographic evaluation – unilateral-image, symmetrical image, and serial images – will be presented. The difference between qualitative (visual) image analysis and quantitative (numerical) analysis is discussed, with emphasis on combining these methods for complete image interpretation. Qualitative analysis involves adjusting the thermal span of the image to fully cover the human color spectrum or grayscale, independent of thermal offset or gain. Once the image has been properly scaled, quantitative measurement sites can be selected. Quantitative analysis of a thermal image is independent of the display palette and the thermal span of the image. Full instructions on various quantitative measurement techniques are given. The best use of average, maximum, and minimum temperature measurements is discussed. The importance of differential versus absolute temperatures is covered, and the use of linear as well as area quantitative analysis is presented.
