In characterizing a color hardcopy device, it is necessary to establish the relationship between the input signals that drive the device and the colorimetric response of the device to these signals. Most printing devices are not adequately characterized by a simple linear transformation; hence one is left with the choice of either measuring the printer's colorimetric response at numerous points throughout the input signal space, or deriving a model to predict the printer's response. In this paper, we examine a model based approach to device characterization. In particular, we focus on a model developed by Hans Neugebauer for binary color printers employing a rotated halftone dot screen. In their simplest form, the so called “Neugebauer equations” are used to predict the broadband reflectance of a halftone pattern printed on paper. In this paper, we investigate the accuracy of the basic Neugebauer equations and several of its modifications. These equations involve some basic constraints which we will assume to be fulfilled throughout the discussion.An important application of the Neugebauer model is the calibration of binary color printers. Calibration, which requires a mapping from colorimetric signal space to the printer signal space, is the inverse problem of device characterization. Hence, calibration requires that the Neugebauer model be inverted. Since the Neugebauer equations are nonlinear, the inversion is not trivial, and requires numerical or statistical approaches (see [3] for examples). In this paper, we do not deal with the inverse calibration problem; rather, we focus only on the forward characterization problem. We evaluate and compare the use of various Neugebauer models to predict the colorimetric response of a Xerox 5775 color printer. This printer uses xerographic technology with four colorants, and has a resolution of 406 × 1624 dpi.