Color is a quality of substance and systems under study that can be reproducibly codified by digital systems using controlled conditions.Thus, the intensity of color is an appropriate parameter for the performing of analyses based on the quantitative monitoring of color changes.The objective of this work was to develop and evaluate a quantitative parameter which permits to carried out the color intensity description of analytical samples for its application in the digital image quantitative analysis (DIQA) and to show its application in the construction of McFarland scale for the determination of colony forming units (CFU) in the microbiology analysis.For that, a surface color index (Isc) was defined from RGB color space.Isc was used as a descriptor of color changes and it was evaluated McFarland Scale RGB model Digital imageColor