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FLEXO Magazine : June 2008
TECHNOLOGIES & TECHNIQUES STANDARD VIEWING CONDITIONS Much of FIRST 4.0 embraces and incorporates as many inter- nationally accepted standards as is possible and practical. A new topic in the design section is Standardized Viewing Conditions. Even if everything else is done properly in the color reproduction workflow, what may seem like a small thing can throw a major wrench in the works-case in point is viewing conditions. Another cold hard fact is that the illumination, or lighting, under which you view something/anything impacts the way you perceive color. It's one ofUthe big three" (sample, detector or receiver, and illumination) necessary to perceive or measure color. Not only do you have the situation where the color of the lighting affects the perceived color of the proof or printed piece, for example, but there's also the issue of metamerism. While there are different types of metamerism, the one we're usually most concerned with is when two samples match under one light source (or viewing condition) but don't under another. How many times have you heard of cases where there's a disagreement on whether the proof matches the printed piece only to find out that the complaining party is viewing them under different conditions than the other? In addition to the light source, or illumination, having a con- trolled environment is important. Items and colors in the pe- ripheral can impact human color perception, so it's best to utilize a viewing booth and be sure that there is nothing hanging or placed in the booth that can be seen peripherally. ANSI 2.30 - 1989 defines the viewing conditions that FIRST 4.0 recommends. It should also be noted that, for best agreement between color measurement and visual assessment, the light source in the view- ing booth and the illuminant chosen in the spectrophotometer should match. For example, CGATS.S - 1993 recommends DSO as the standard illuminant. So, the bulbs in the viewing booth should be DSO as should the illuminant selected in the spectro- photometer. When all parties in the color reproduction process use the same lighting and viewing conditions, it removes one source of potential discrepancy should there be a concern over the quality of the color match. PROCESS CONTROL TEST ELEMENTS In order for the printer to control the printing process, certain process control test elements must be included somewhere on the form. This has typically not been of concern for the designer, but two things have changed this situation: 1. CPCs are better understanding and realizing the need to have these elements on the pressrun for the printer to mea- sure and control the process. 2. Space is oftentimes limited thereby forcing the issue of in- cluding the control patches into the I-up design be it in a minor flap, a glue zone, the waste matrix area, etc. The other dynamic is that by only placing the test elements in the scrap areas of the form (if there is even space), the printer may either not get enough information about how the job is printing or get information not representative of the print perf or- mance of the design. This makes it difficult to adjust and control the pressrun to achieve target color. By incorporating the test ele- ments into the design somehow, they are much more indicative of what's going on in the saleable product. That is built-in con- fidence. More and more we are seeing these funny little squares and circles on bags and cartons. This is no longer a no-no in the eyes of the CPC; they understand the value of them. Typically it is best to include the following process control test elements for each color: . Solid Patches. These allow the printer to measure and moni- tor solid ink density (SID) and/or color of the solids for spot, or custom, colors. . Halftone Patches. These allow for monitoring and control- ling dot area/dot gain, also known globally as tone repro- duction. At least one patch should be incorporated (more if space allows). The printer should be involved in which tint patches are included. . Overprint Patches. When printing process color (CMYK), it is critical that the overprint primaries (red, green, and blue) print consistently and repeatedly. . Gray Balance Patches. These are made up of cyan, magenta, and yellow which in combination produce a neutral gray (as determined from a prior fingerprinting run). Gray balance is useful in determining quickly if something has changed, but one or more of the other patches (above) are needed to diag- nose the change. Often, a black tint of the same lightness is placed next to this patch as a visual reference of neutrality. . Registration Marks. These could be for print-to-print align- ment of the separations or for print-to-cut applications. Good communication between the designer, CPC, prepress provider, and printer should exist so that the needs of all are un- derstood and communicated as best as possible up front. Further, it can be determined where and how the test elements should best be incorporated. USPS INTElliGENT MAil BAR CODE New to FIRST 4.0 is the inclusion of the United States Postal Service Intelligent Mail Bar Code (CB4), which is used in high- speed mail applications. It comes from the USPS-B-3200C speci- fication and defines parameters such as horizontal dimension, vertical dimension, quiet zone, vertical and horizontal position- ing, content information, and font specifications. These are just some of the changes and additions made to the design section of FIRST 4.0. With each version comes new ap- proaches and updated information. The core mission of FIRST has not changed, and the better we all understand the entire pro- cess, the better we can all contribute in our specific areas toward stellar printing and packaging that meets or exceeds the expecta- tions of the customer while doing so in an efficient manner for all the stakeholders so that flexography continues to thrive, grow, and continuously improve. . JUNE 2008 - www.f I exog ra p hy.o rg FLEXO