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FLEXO Magazine : May 2013
of the data. Tools to convert “noisy ” data to smooth data now enable us to work under less than perfect conditions. And while test target design and data smoothing have contrib- uted greatly to color profile accuracy, the technology to have the greatest impact is the ability to synchronize a profile to a curve specification. It’s also the technology that is the least understood. Understanding the principle of synchronizing to a specifica- tion starts with understanding the principle of printing to a speci- fication. This has been the subject of many articles in FLEXO and other printing industry publications over the last 10 years. In essence, printing to a curve specification is a matter of deciding how you want all of your dot sizes to print for all of your colors. The most common CMYK specification today is G7. To cite just one item from the large G7 spec, a Black dot which reads 50 percent in the digital file, should print to 70 percent on the final printed sheet. If your color profile is “in sync” with the G7 curve specification, then the 50 percent “slot” in the profile table will contain a value which is the L*A*B equivalent of a 70 percent dot. Tools exist to check profiles today to see if your profile is “in sync” with your spec. Results of using these tools, with real profile data, reveal that profiles are rarely “in sync. ” To be more specific, it ’s occasionally true for one color, rarely true for CMYK, and almost never true for the seven colors of ECG. To under- stand the principle of synchronizing, you have to first understand that if your profile is not in sync with your spec. (i.e if your K 50 percent is not K 70 percent, then when you do print to your spec at some point in the future, your color will be inaccurate.) Synchronizing the profile means adjusting the data, so that maximum accuracy will be achieved when you do print to your spec. It also means that, over time, when your conditions change, all you’ll need to do is adjust your curves to get back to your spec. You will not have to make new profiles, build new ink books, build new tint books, make a new proofer match etc. It should be noted that synchronizing only affects tint val- ues. If your ink colors change, you’ll have to re-profile. Fortu- nately, most changes in flexo printing are related to changes in dot gain. Tint Build Logic: Tint build logic related to color accuracy has become understood to a far greater degree in just the last two or three years. Even for CMYK process, there are an infinite number of combinations of the four colors that can match a given spot color. For example, consider a mid-tone gray with L*A*B values of L=50, A=0, B=0. Such a color might be reproduced with C=50, M= 0 , Y=50, K=0, or with C=0, M=0, Y=0, K=50, or with a virtually infinite number of other combinations. But It’s a fact that a 7-color ECG press has a smaller color gamut than a 12-color ink mixing system. Through the use of dependent standard ink books, CPCs and designers who know this up front are in a much better position to work with the 7-color press gamut. Through the use of digitally distributed “dependent standard” ink books, CPCs and designers know the limitations at the beginning of the process. A printer committing to achieve Pantone 186 is in a far better position to match L=45, A=64, B=43, than to match L=45, A=68, B=40. 34 FLEXO may 2013 www.flexography.org