Carlos Carazo

Abstract

Optical Brightening Agents (OBAs) are chemicals added to paper pulp whose purpose is to brighten the white point of the paper. Adding OBAs results in a brighter white, increased tonal range, and more chromatic colors. However, adding OBAs can also create problems in visual print-to-proof match where proofing substrates do not contain OBAs. Visual print-to-proof match is the final judge of conformance in a print business. When printing and proofing in conformance to standards and specifications on non-OBA papers, there is visual match between the print and the proof. Printing on OBA loaded papers causes two main problems: (1) difficulty in achieving conformance to printing standards and (2) visual print-to-proof mismatch. To solve the above problems, this research begins by adopting the new "M1" measurement condition and the revised ISO 3664:2009 viewing conditions. It then assumes that the print on OBA loaded paper is the anchor and the proof must be color managed to match the print using these new measurement and viewing conditions.

In order to test the proposed solution, the researcher prepared a series of prints and proofs that (1) reproduced the proof-to-print match traditionally achieved on non-OBA loaded printing papers (the anchor pair), (2) reproduced the proof-to-print mismatch on OBA loaded printing papers (the problem pair),

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and (3) tested the color managed approach to solving the problem described above (the solution pair). Finally, these pairs were evaluated by a panel of observers in a paired comparison experiment under the revised ISO 3664:2009 viewing conditions.

The results of the paired comparison experiment first demonstrated that the researcher could reproduced both a proof-to-print match on non-OBA loaded papers and a proof-to-print mismatch on OBA loaded papers. In addition, the solution pair was demonstrated to be preferred to all other pairs at the .05 level of significance. Finally CIELAB plots of the problem pair and the solution pair under M1 conditions supported the results of the pair comparison experiment. Under M1 conditions the proof-to-print mismatch (difference in CIELAB values) for the problem pair was shown to be approximately twice as large as the proof-to-print mismatch for the solution pair.

Based on the results of this research, the proposed solution was shown to be a promising approach for solving the industry wide problem of print-to-proof mismatch when printers print on OBA loaded papers.

Library of Congress Subject Headings

Paper--Printing properties--Testing; Optical brighteners; Imaging systems--Image quality--Testing

Publication Date

4-26-2012

Document Type

Thesis

Student Type

Graduate

Degree Name

Print Media (MS)

Department, Program, or Center

School of Design (CIAS)

Advisor

Robert Chung

Advisor/Committee Member

Robert Eller

Comments

Physical copy available from RIT's Wallace Library at Z247 .C37 2012

Campus

RIT – Main Campus

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