It is well known that the spectral sensitivities (SS) for color imaging devices should satisfy the Luther condition that requires SS to be linear combinations of the CIE color matching functions. In practice, it is difficult to construct an SS exactly to meet this condition. Some quality factors such as q-factor for single SS by Neugebauer and μ-factor for a set of SS by Vora et al. were introduced in order to describe the deviation of SS from their nearest color mixture curves. In this article, a simple method is presented to implement an evaluation platform for the above two quality factors. A series of hypothetical spectral sensitivities are constructed with cubic spline functions with shape and peak position of the SS parametrically varied. The evaluation plat-form is used to optimize these SS parameters to obtain a maximum quality factor. Furthermore, the improvement of quality factor by adding a fourth SS is proposed and the relationship between quality factor and human perceptual judgement is discussed in this article.