Various embodiments of systems and methods for calibrating wafer inspection system modules are disclosed herein. More specifically, the present disclosure provides various embodiments of systems and methods to calibrate the multiple spectral band values obtained from a substrate by a camera system included within a WIS module. In one embodiment, multiple spectral band values are red, green, and blue (RGB) values. As described in more detail below, the calibration methods disclosed herein may use a test wafer having a predetermined pattern of thickness changes or color changes to generate multiple spectral band offset values. The multiple spectral band offset values can be applied to the multiple spectral band values obtained from the substrate to generate calibrated RGB values, which compensate for spectral responsivity differences between camera systems included within a plurality of WIS modules.