Di-Yuan Tzeng

Abstract

Conventional four-color printing systems are limited by an insufficient number of degrees of freedom for tuning the visible region of the spectrum; as a consequence, they are often limited to metameric color reproductions. That is, color matches defined for a single observer and illuminant (usually CIE illuminant D50 and the 1931 standard observer) are often unstable when viewed under other illuminants or by other observers. For critical color-matching applications, such as catalog sales and artwork reproductions, the results are usually disappointing due to typical uncontrolled lighting and viewing. Furthermore, the existing multiple-ink printing systems, which all focus on expanding color gamut, do not alleviate metamerism since their separation algorithms are trichromatic in nature. The advantage of an increased number of degrees of freedom is not exploited. A research and development program has been initiated at the Rochester Institute of Technology's Munsell Color Science Laboratory to develop a spectral-based color reproduction system Research has included multi-spectral acquisition systems and spectral-based printing. The current research is concerned with bridging these analysis and synthesis stages of color reproduction. The goal of the doctoral research was to minimize IV metamerism between originals and their corresponding reproductions, thus best approaching spectral matches. Accomplishing this goal required first estimating the spectral properties of the colorants used to create the original object or set of objects. After the possible colorants were statistically uncovered, they were correlated to an existing ink database for determining an optimal ink set. An algorithm was developed for predicting ink overprints, known as the Neugebauer secondary, tertiary, quaternary primaries, etc., which is the required information for color synthesis using a halftone printing process. Once all the required Neugebauer primaries were determined, a spectralbased printing model minimizing metamerism was derived to calculate the corresponding color separations for each selected ink. The various research components were tested computationally and experimentally. Finally, a DuPont Waterproof system was used as a representation of halftone printing process to output each color separation in order to test several computational subsystems. This completes the chain of a spectral-based output system. Five modules of this chain were developed and discussed in this dissertation.

Library of Congress Subject Headings

Color separation; Color printing; Imaging systems--Image quality; Spectral synthesis (Mathematics)

Publication Date

9-1-1999

Document Type

Thesis

Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)

Advisor

Berns, Roy

Advisor/Committee Member

Fairchild, Mark

Advisor/Committee Member

Arney, Jonathan

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: Z258 .T93 1999

Campus

RIT – Main Campus

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