On field sequential color (FSC) displays, a frame of an image is represented by sequentially displaying multiple fields. In the case of FSC displays without color filter, light transmission efficiency can be improved and power consumptions can be reduced. Sequential displaying of multiple fields results in undesirable color artifacts near boundaries of moving objects. They are often called as color breakup (CBU). They are two types of the CBUs on the FSC displays : dynamic and static. This paper presents a method to measure degree of CBUs that can be applied to natural color images. Applicability and effectiveness of the CBU model is verified by human visual experiments. Experimental results indicate that the proposed model faithfully matches with the degree of CBU perceived by human observers.