In an earlier paper, we modeled the axial chromatic aberration of the human eye with an optical transfer function (OTF). The OTF quantifies the interaction between wavelength and spatial pattern in retinal image formation, and therefore has important consequences for color perception and image matching. However, using the OTF for practical calculations can be quite cumbersome. Here, we show how using finite dimensional linear models for surface and illuminant spectral functions greatly simplifies these calculations in certain cases. In our earlier wow, we applied our model to the problem of matching color images on missive displays; we show here how this application is a special case of this use of linear models.