Using the example of the determination of nitrite as polymeric azodye, the possibility of using office scanners, digital cameras, and computer data processing in different colorimetric coordinate systems (RGB, CMYK, LAB, and HSV) has been studied. Polymeric azodye was obtained by an azocoupling reaction between diazotized polyurethane foam (PUF) with 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline. The analytically important colorimetric coordinates in these systems were revealed and compared and the coordinates that result in the maximum sensitivity of nitrite determination were chosen. It was shown that calibration curves of the colorimetric coordinates versus concentration of nitrite in aqueous solution can be described by a first-order exponent. The detection limits of nitrite (1–3 ng/ml) were achieved in the RGB and CMYK colorimetric systems.