Achieving gray balance in presswork is the major mantra in today's print production world. It is the paramount metric - now defined in unambiguous CIE L*a*b* values - for the G7™ calibration method to align press and proof color as well as for achieving presswork that conforms to GRACoL® 7. That being said, one must keep a "balanced" view on gray balance as a metric in presswork. While it certainly has value - interpreting that value requires some understanding of the peculiarities of the press room as well as a bit of history.

1. As far as I can determine there has never been a formal study of gray balance targets measured in press sheet color bars and how they relate to the live image content of the press sheet.
2. Press operators do not "make color" on press. They concentrate on what a press is designed to do - lay down a consistent film of ink approximately one micron thick on the substrate.
3. Press operators use densitometers - not to measure color, but to indirectly measure ink film thickness.
4. The deepest study that has been done on gray balance was by System Brunner using densitometers rather than spectrophotometers to measure gray balance.
5. The ISO specification (e.g. ISO 12647-2, ISO 2846-1) defines gray balance as "neutral" - a very vague term.
6. A press lays ink down in a series of zones which run from the lead edge to the tail of the sheet. If a specific process color (C, M, Y or K) is not require in that zone because of image content, that ink zone is switched off and gray balance is no longer achieved in the color bar.
7. Image content that requires a substantial increase in solid ink density in some colors (e.g. a sunset scene) will result in  gray balance no longer being achieved in the color bar.
8. The correlation of gray balance distortion (i.e. color bias) vs perceived color shift in quarter, mid and shadow areas has not been studied. It is probable that it is very non-linear. That is to say that the shifts we see in the gray balance target in the color bar may shift quite a it, however, we will not necessarily see an equal shift in highlight or shadow color.
9. Gray balance targets are likely too sensitive to normal color fluctuations on press to be of practical use. Just like a car's speedometer would be useless information if provided 3 decimal place readouts of speed (e.g. 50.392/kmh, 50.471/kmh, 50.148/kmh).
10. It is dangerous to apply gray balance principles derived from scanning and proofing to the pressroom since the mechanics of how color is achieved is radically different.
11. The job of the press operator is to align the "live" image area of their presswork with the proof by achieving the appropriate solid ink densities since printers sell the live image area of the press sheet - the color bars go into the recycling bin.

Gray balance targets in presswork color bars certainly have some value - but interpretation of the information they contain must always be considered in the context of the mechanics and chemistry of the press itself.

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Earlier this year, Kodak contracted with spencerLAB, an outside image quality laboratory, to perform an independent comparison of the print quality of the Stream Concept Press print samples and use image quality measurements to compare these to offset printed samples. Here's what they had to say about the Stream Concept Press:

• Our analysis found that overall, the Stream Concept Press from Kodak demonstrates the potential of approaching 175-line offset print quality.
• Images were one area of impressive print quality, particularly on glossy media. Gamut volume was 35% larger than 175-line offset in our tests.
• Black density was 29% higher compared to offset.

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As someone who has made the jump over the digital divide from the commercial offset world, I can tell you that sometimes the chasm is much larger than I expected. I mean, how different can printing really be if you're putting colored drops of an ink-like substance onto paper or other substrate? But in my ten months as product marketing manager responsible for products touching the commercial market, I have seen the differences between the high-speed inkjet world and high-production commercial environment getting smaller.

Having had the opportunity to travel to a number of web-offset printers in the Chicago area I was able to see how the integration of Kodak Versamark print heads in-line with vintage Harris, Heidelberg Web and Goss equipment have given these presses a new purpose in life - a new life in the digital world.

By adding inkjet these commercial printers are being able to offer relevant, personalized offers, directions (area maps), discount coupons and of course, addressed to recipients by their ACTUAL name rather than "Dear Valued Customer", which we all know doesn't fly any longer since we really can't be very "valued" if they don't even know or care to buy our name from a list. But I digress.

So why is it that there are still so many offset printers out there who are "running digitally scared"? I can count on all my fingers and all of my toes the number of printers who came up to me during drupa, and had that moment of revelation when they realized they had a similar looking web offset press like the one we had running at the show, in their shop, but that all of the pages we were producing were imprinting unique digital information in the white spaces at 600 dpi and offset-class, quality text - 100% variable with different names, offers and maps all based on a fictitious rewards program that determined the type of travel offers and discounts. On more than one face did I see that enlightened look of "wow, I should be doing this on my offset presses" and if the individual was really impressed, it usually prompted a discussion with one of our Kodak folks standing press-side. How many of these folks we convinced that this is a great way to enter into the digital world by way of retrofitting their offset presses, I don't know, but I do know there are still many offset folks out there who should be considering hybrid digital printing as a new opportunity.

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