A general issue for clinical medicine is whether to treat asymptomatic patients who present with bacteria in their urine. Because of increasing antimicrobial resistance, it is important not to treat patients with asymptomatic bacteriuria unless there is evidence of potential benefit. For this purpose, a urinalysis dipstick reagent color acquisition is important, mainly for leukocytes esterase and nitrites reagent which can be an indicator for early detection of Urinary Tract Infection (UTI). Smartphone camera can be used to help people interpreting reagent colors, rather than using expensive instrument that can only be used by professionals.To accomplish that goal a system that can interpret reagent colors and can be installed on smartphone is needed. One of the main issue in developing this system is what color space and method are used, so the values extracted can represent color in the dipstick for further process to obtain reliable result . Reagent detection and acquisition system uses CIELab color space and Stepwise Linear Interpolation based method to measure the level of leukocytes esterase and nitrites reagent in urine. Experimental result proves that Stepwise Linear Interpolation can determine reagent level of nitrite and leukocytes. But, black white calibration can't representing light calibration so data master can't be applied. And in some situation, a further experiment is needed for producing reliable method for determining reagent level which are not represented in the color chart.