Near-continuous-tone electronic color printing on low-sensitivity photographic materials

Two electronic exposure systems employing active-matrix addressed liquid crystal light modulators are described for printing on lowsensitivity photographic materials such as the new 3M Dry Silver Color and Mead Cycolor™ papers. The feasibility of using a liquid crystal light modulator to expose these new materials was first demonstrated on a system employing simple projection optics. The image quality, printing speed, and complexity of projection type systems make them poor candidates for low-cost video printers. A new Multiline Multilevel Scanned Printing System, which is especially well suited to printing with liquidcrystal light modulators, is described. This is a large-aperture digital technique using an incandescent light source. It can produce a near-continuous-tone color print on photographic materials in a single pass below the light modulator. The system is intrinsically insensitive to isolated defects in the modulator and can also easily accommodate corrections for single pixel and column defects. The system has been used to make prints on a variety of photographic materials varying by over three orders of magnitude in sensitivity. A figure of merit is introduced that can be used as a starting point when one is comparing various exposure schemes.