Volume 22, Number 4 - October 2006 through December 2006 Analysis of Newsprint Color Reproduction within the Newspaper Association of America Solid Ink Density and Color Gamut Standards By Dr. H. Naik Dharavath Peer-Refereed Article KEYWORD SEARCH Graphic Communication Printing Quality Control Research Visual Communication The Official Electronic Publication of the National Association of Industrial Technology • www.nait.org © 2006 Journal of Industrial Technology • Volume 22, Number 4 • October 2006 through December 2006 • www.nait.org Analysis of Newsprint Color Reproduction within the Newspaper Association of America Solid Ink Density and Color Gamut Standards Dr. Dharavath is an Associate Professor of Graphic Communications Management at the University By Dr. H. Naik Dharavath of Wisconsin-Stout. He received a Bachelor of Sci- ence in Graphic Communications Technology from Rochester Institute of Technology (1995), a Introduction solid ink density (SID), dot gain (DG) Master of Technology in Graphic Communications and print contrast (PC). For this study, from Arizona State University (1998), and a Ph.D. In the process of multicolor offset in Applied Science and Technology Education printing, a paste ink of a given color only the SID was used to examine the from University of Wyoming (2002). Dr. Dhara- significant difference that exists in vath teaches Graphic Communications/Electronic – yellow, magenta, cyan, and black Publishing and Postpress/Distribution Operations (CMYK) is transferred from the ink the day-by-day leading national daily Management courses. In addition to teaching, he newspaper over a period of time (25 advises UW-Stout TAGA Student Chapter, which fountain to the series of inking rollers received the First Place Award for overall quality and then to the image areas of the plate days). Also, color variation was exam- of Non-Print Edition of the Student Journal in 2004. His research interest in Graphic Communications (image carrier). The inked image area ined by comparing the actual color CIE Technology includes Print Manufacturing Manage- of the plate is then transferred to the L* a* b* values to the NAA standard ment, Curriculum Development, Educational Pro- gram Evaluation and Assessment, and Print Quality blanket, and from the blanket it is trans- CIE L* a* b* values. Management (Color Management, TQM/SPC, and ferred to the paper. A continuous tone Colorimetric Analysis). color, or black and white photograph, is Purpose of the Research composed of a full spectrum of shades The purpose of this research was to and color, from near white to dense analyze the newsprint color reproduc- black. The method by which a continu- tion within the Newspaper Association ous tone photograph is transformed to a of America Solid Ink Density (SID) and printable image is called halftoning, in Cyan, Magenta, Yellow, Red, Green which varying percentages of the press and Blue (CMYRGB) Gamut Stan- sheet are covered with halftone dots dards. The following questions were to represent the varying tones in the investigated. image. In the conventional halftoning 1 Is there a difference (variation) in the process these dots are equally spaced. SID values (CMYK) of the printed However, the size or diameter of the newspaper vs. NAA SID (CMYK) dots will vary according to the differ- Standard values? ent amounts of light that were reflected 2. Is there a difference (variation) in from the different tones in the original the Average and Range SID values photograph. The ink printed by each (CMYK) of the printed newspaper dot, of course, has the same density. At over a period of time (25 days)? normal viewing distance, the dots of a 3. Is there a color (CMYKRGB) differ- printed image create an optical illusion ence (variation) of the printed news- of a continuous tone image. paper CIE L* a* b* values vs. NAA color (CMYRGB) Standard CIE L* In order to print a quality halftone im- a* b* values? age, the printer (or press operator) must carefully manage several variables and Limitations of the Study attributes which are associated with the The print characteristics associated printing process. The print attributes with printed newspaper are character- are individual characteristics within the ized by, but not restricted to, inher- printing process that can be monitored ent limitations; for example: type of during the production process so as to printing process, type of substrate, type maintain the color consistency. The of ink, etc. There are several variables commonly monitored attributes include affecting the facsimile reproduction of newspaper color and most of them are 2 Journal of Industrial Technology • Volume 22, Number 4 • October 2006 through December 2006 • www.nait.org mutually dependent on each other. The gain, and print contrast (Lustig, 2001). light reflected from printed material or scope of the research was limited to the Stanton & Hutton (1999) stated that continuous tone photographs (Brehm, offset (lithography) printing systems some attributes are not monitored be- 1992). In the prepress and printing/ and instruments and data collection cause they are not readily measurable. press areas of the industry, densitom- techniques used at the University of SNAP standards are limited to coldset etry allows us to find a balance for Wisconsin-Stout’s graphic commu- web offset reproduction on uncoated accurate tone reproduction. Hseih nications laboratory, and the findings groundwood paper only (SNAP, 2005). (1997) stated that a densitometer can were not expected to be generalizable A majority of the newspapers in the measure either incident light reflected to other printing environments. Only country are printed by using the coldset from a substrate (reflection density), the print attributes that utilize solid offset printing process (NAA, 2006) light transmitted through a film (trans- ink patches were examined, as it is an mission density), or both. In prepress important attribute that represents over- Offset Printing Process and printing/press areas, the Status T all color coverage in the printing. The Offset printing is a planographic print- densitometers have been used exten- research methodology, experimental ing process, also known as chemical sively for measuring densities. Status design, and statistical analysis were all printing. It uses a flat aluminum plate T is the ANSI/ISO (American National selected in alignment with the purpose (image carrier) on which image and Standard Institute/International Orga- of the research with full awareness of non-image areas are generated photo- nization for Standardization) standard the aforementioned delimitations. The chemically or electronically. The basic for wideband densitometer response NAA and others would find this study principle of offset printing is that water for measuring print attributes (Brehm, meaningful and useful. (or dampening solution) and ink (or oil) 1992). These instruments are important do not mix. The image area of the plate quality control tools for the industry. Review of Literature is receptive to ink and the non-image In the printing/press area, a reflection The Newspaper Association of America area of the plate is receptive to water densitometer allows us to measure (NAA) is a nonprofit organization rep- (Hseih, 1997). The dampening solution characteristics of print attributes such resenting the US $55 billion newspaper is a mixture of chemical concentrate in as solid ink density, ink trap, dot gain, industry. It was established in 1992. a water-based solution. The basic con- print contrast, gray balance, etc. In the NAA members represent nearly 90 per- figuration of a single color offset press prepress area, a transmission densi- cent of the daily newspaper circulation consists of three cylinders – plate, blan- tometer allows us to measure halftone in the United States (U.S.) and a wide ket, and impression. The plate, which film density and dot area values, which range of non-daily U.S. newspapers holds image areas in readable direc- are used to linearize the filmsetter (see (NAA, 2006) tion, is mounted on the plate cylinder, Figure 2). dampened all over its surface, and then In 2005, NAA published the Speci- the plate surface is contacted by a series fications for Newsprint Advertising of inked rollers. The inked areas (image Production (SNAP). It was developed areas) transfer onto the surface of the by a committee formed by the NAA to blanket cylinder where they become develop a document containing general non-readable, and then onto the paper guidelines and recommendations that where they become readable. The paper could be used as a reference source passes between the impression cylinder across the newspaper industry for qual- and blanket cylinder (see Figure 1). ity printing (SNAP, 2005). The SNAP Quality printing is a primary objective standards provide a broad spectrum during the press run. The press opera- of recommendations and standards tor will manage and monitor several regarding the production of newsprint variables and print attributes. production (SNAP, 2005). It consists of guidelines and charts giving aim points Densitometric Measurements and tolerances for a variety of print A densitometer is a scientific instru- attributes (SID, CIE L* a* b*, DG, and ment which is designed to determine, PC). Print attributes are defined as the indirectly, the light absorbed by a individual characteristics within the surface (Brehm, 1992). There are two printing process that can be measured types of densitometers: transmission and monitored during the production so and reflection densitometers. Transmis- as to maintain the quality consistency. sion densitometers measure the amount The most commonly monitored print of light that is transmitted through a attributes, and the ones concentrated transparent material such as a half- Figure 1: Schematic Diagram of Offset on by the researchers, include solid tone film or color negative. Reflection Printing Unit Design ink density, CIE L* a* b* values, dot densitometers measure the amount of (Courtesy of GATF) 3 Journal of Industrial Technology • Volume 22, Number 4 • October 2006 through December 2006 • www.nait.org Density R = log 10 (1/R) (X-Rite, 2002).