In order to rationally realize a production environment in the future, it has become of the utmost importance to investigate and develop sensing technology for ambiguous quantities, which enables the six senses of humans to be replaced by engineering methods. In particular, it is essential to develop an in-process monitoring system for ambiguous quantities based on the visual sense, which can simultaneously automate the conventional inspection procedure on a production line. In this paper, therefore, to establish sensing technology for color unevenness, a multidimensional quantitative evaluation method has been proposed for the first time. The validity of the proposed method has been verified through some case studies by applying it to image processing of plastic injection mold products.