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Rochester Institute of Technology RIT Scholar Works Theses Thesis/Dissertation Collections 5-1-1998 An Analysis of available unsharp masking techniques used with mid-range PMT/drum scanners Eric Neumann Follow this and additional works at: http://scholarworks.rit.edu/theses Recommended Citation Neumann, Eric, "An Analysis of available unsharp masking techniques used with mid-range PMT/drum scanners" (1998). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. An Analysis of Available UnSharp Masking Techniques Used With Mid-Range PMT/Drum Scanners by Eric Louis Neumann A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the School of Printing Management and Sciences in the College of Imaging Arts and Sciences at the Rochester Institute of Technology May 1998 Thesis Advisor: Professor Joseph L. Noga School of Printing Management and Sciences Rochester Institute of Technology Rochester, New York Master's Thesis Certificate of Approval This is to certify that the Master's Thesis of Eric Louis Neumann With a major in Graphic Arts Publishing has been approved by the Thesis Committee as satisfactory for the thesis requirement for the Master of Science degree at the convocation of May 1998 Thesis Committee: Joseph L. Noga Thesis Advisor Marie Freckleton Graduate Program Coordinator C. Harold Goffin Director or Designate An Analysis of Available UnSharp Masking Techniques Used With Mid-Range PMT/Drum Scanners I, Eric Louis Neumann, prefer to be contacted each time a request for reproduction is made. I can be reached at: P.O. Box 261 Itasca, IL 60143-0261 [email protected] Graduate Student May 1998 Acknowledgements The completion of this thesis would not have been possible without the assis tance, support, and patience of many companies and individuals that I owe my gratitude to. I must pay special recognition to Professor Joseph L. Noga for his support and mentorship over the years that I spent both as a student and employee of RIT The School of Printing Management & Sciences, RIT Prof. Marie Freckleton Prof. Len Leger Ms. Grace Gladney And the rest of the SPMS faculty and staff Screen Mr. David Mitchell Howtek Mr. Joel Hofmeister Optronics Mr. Don Rogers FujiFilm USA Mr. Allen Dunn Ms. Jan Mullen Family and Friends Mr. Ethan Crist Mr. Carl Ogawa My Mother, Susan Elmore in Table of Contents List of Tables v of List Figures vj Abstract vjj Chapter 1 Introduction \ Chapter 2 Theoretical Basis of Study 3 Endnotes for Chapter 2 24 Chapter 3 Review of Literature 25 Endnotes for Chapter 3 27 Chapter 4 Statement of Project Goals 28 Chapter 5 Methodology 30 Chapter 6 Results of Evaluation 33 Endnotes for Chapter 6 58 Chapter 7 Summary and Conclusions 59 Bibliography 66 Appendices 69 IV List Of Tables Table 6.1 - Controls of USM on scanners evaluated 34 Table 6.2 - Mask colors resulting from color sensitivity filters 55 Table 7.1 - Scanning times 62 List of Figures Figure 2.1 - O'Brien Effect 9 2.2- Figure Anatomy of a peaking signal 11 Figure 2.3 - Direct screen mask exposure 13 Figure 2.4 - Direct screen separation exposure 13 Figure 2.5 - Photomechanical unsharp masking 15 Figure 2.6 - Optical unsharp masking 18 Figure 2.7 - Digital unsharp masking 20 Figure 2.8 - Hybrid unsharp masking 22 Figure 6.1 - USM controls in Adobe Photoshop 4.0 35 Figure 6.2 - USM controls in DT-S Scan 3.4 36 Figure 6.3 - ResEdit interface to DT-S Scan 3.4 38 Figure 6.4 - Screen USM effects 41 Figure 6.5 - Directional characteristics of DT-S 1030AI 42 Figure 6.6 - USM controls in Trident 2.0 44 Figure 6.7 - Howtek USM effects 49 Figure 6.8 - Directional characteristics of ScanMaster 4500 50 Figure 6.9 - USM controls in ColorRight 5.0 51 Figure 6.10 - Optronics USM effects 56 Figure 6.11 - Directional characteristics of ColorGetter Eagle 57 VI Abstract Unsharp masking (USM), also known as detail enhancement, is a process of combining an unsharp representation of an original image with the original image to obtain the effect of greater detail. USM can be performed photomechan- ically with additional exposures, electronically with the color scanner, and digi tally with the aid of a post-processing program. Electronic methods of USM per formed during the scanning process offer productivity benefits over both the photomechanical and post-processing methods. Mid-range PMT/drum scanners offer several methods of unsharp masking from which to choose. These meth ods, optical USM, digital USM, and hybrid USM each have advantages and dis advantages which are identified in this study. The study also offers an extensive reference of the available USM techniques for identification by the mid-range scanner operator. Three different midrange scanner/ interface applications are evaluated to identify their unique USM methods and each is evaluated for ease- of-use as well as the effectiveness of it's unsharp masking function. Multiple scans from each scanner/interface combination were completed and analyzed at high magnification. It was expected that more directional limitations would have been evident in the optical method, however it is shown that it's effectiveness does not suffer. Each of the USM techniques used on midrange PMT/Drum scanners has its own merits. vn Chapter 1 Introduction Unsharp masking is a necessary function in the process of making color separa tions. It is necessary in order to compensate for the visual loss of detail caused by the printing reproduction process. The concept is not new. It has been part of the color separation process since long before the introduction of the electronic color scanner. The unsharp masking technique was first introduced with the photome chanical color separation methods known as indirect and direct screen color sep "unsharp" aration. An additional exposure created an mask that was combined with the original in a successive exposure to provide detail enhancement in the reproduction of an image. Color separation programs used on desktop systems today (e.g. Adobe Photoshop), now provide a way to simulate the combination of a digital unsharp image (filter) with the original to provide detail enhance ment in the reproduction as a function of post-processing. Unsharp masking per formed during the electronic color scanning process offers increased productivi ty over photomechanical and post-processing techniques. Mid-range scanners are the most recent entry into the electronic color scanner market. These scanners and their accompanying software interfaces have the benefit of more than twenty-five years of color separation advancements. Among these advancements are the refinements to the unsharp masking process. There are now several options available to the manufacturers of mid-range scanners and in some instances to the users of the mid-range scanners. 1 This study provides both an extensive reference to the unsharp masking tech niques available on mid-range scanners as well as an analysis of these tech niques, identifying their advantages and disadvantages. Chapter 2 Theoretical Basis of Study It is first necessary to provide the definitions for the terms mid-range scanner and unsharp masking. The definitions and explanations of those terms as they were used in this study follow. Definition of Mid-Range Scanners Today electronic color scanners have been segmented into three different classifi cations; high-end scanners, desktop scanners, and mid-range scanners. Unfortunately the boundaries between these classifications is not well defined. As such, there are essentially two methods to define scanners today: either by their technical definition or by their marketing definition. Technically, the scan ners' classification may be defined by their components and specific technology. Marketing classifications may be defined by their cost and target markets. A "mid-range" scanner classified as by its technical definition could very well be "high-end" "desktop" classified as either or depending on the market. The technical definition. In the early 1970's, before any of the confusion, all scan ners were known as electronic color scanners and primarily used photo-multipli er tubes (PMT). With the introduction of charge-coupled device (CCD) scanners in the early 1980's a distinction became necessary. The result was the identifica "high-end" "desktop" tion of the and scanner classifications. High-end scanners were drum-based, had PMTs and onboard separation computers, and used pro- prietary processing techniques. Desktop scanners were flatbed, had CCDs, required a personal computer and software for separations, and generally used open system (non-proprietary) processing techniques. Each system had its bene fits and limitations. The next logical developmental step was to link the existing high-end scanners to the desktop computers and software, capturing the benefits of both systems and eliminating many of the limitations. The link provided the necessary translation between the high-end and desktop processing techniques. As this hybrid link between the systems became more in demand, a new classifi cation was realized. In the early 1990's manufacturers began to build desktop compatible scanners with many of the high-end components, creating what is scanner.1 now referred to as the mid-range The marketing definitions. The lines drawn between the scanner classifications become increasingly unclear. By some marketing definitions, any scanner that "desktop" connects to a personal computer can be considered a scanner (e.g. Crosfield/Fuji Celsis). At the same time, several manufacturers are producing flatbed CCD scanners that exceed the high-end both in quality and price, refer "high-end" flatbed scanners (e.g.

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