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.

For some, the term "old technology" resonates a bad feeling about a product. For those who keep up with all technology aspects around them, this is not necessarily true. The internal combustion engine is old technology that has survived for over 100 years.

Following this concept, Kodak makes a Premier Digital Color Half-Tone Proofer for the graphics industry. Even though it is based on so called "old technology" ( I prefer to say we were way ahead of our time), the Approval NX Digital Half-Tone Proofer is still the standard of half-tone proofing for the industry.

The Approval system has images that are so precise that dot-on-dot registration is evaluated with very high power optics to insure reliability and consistency. Look at any magazine with a magnifying glass and you"ll see the same dots as our machine makes.

So you might ask yourself exactly how good this system is? The proofs off the Approval XP4 (initial system) were used as the "visual reference" for Spot Color and N-Color proofing tests at the 2007 IPA Proofing RoundUP. All the other 34 proofers were measured against our hard copy proof. This system also has Gracol and SWOP certifications.

For those of you who never knew, Kodak has been making this product all along. There are also new enhancements for the Packaging market. Our proofs have been laminated to cardboard for boxes, shrink wrap for bottles and metal for cans so customers can see the actual end product. Being able to replicate the final product saves time and money for the customer. We can also create millions of colors.

Did you know Approval proofs are used to make the company's ONE magazine? Many brand owners worldwide specify the need to use proofs from our machine because of it's accuracy.