Digital presses run the (color) gamut

April 1, 2010

Johnson’s World by Steve Johnson

A designer asked how color differences between two HP Indigo digital press models would impact the quality of a book he was planning.

I questioned why he was restricting himself to Indigos. He replied that he had queried online about the best digital press, and several people had recommended the HP Indigo.

Digital is different

As digital printing moves out of the realm of exotic specialty and into the mainstream, we must learn to ask the correct questions. Our designer runs the risk of “digital disappointment” if he does not alter his approach.

If you had a project for conventional print, would your primary concern be the make and model of the offset press used in the process? I think you would be far more interested in the printing company's reputation for quality, its quality control processes and procedures, and samples of its work. The physics of lithography do not vary much from one machine model to another.

Not so in digital! Every digital press model uses its own unique patented process from start to finish. You cannot, for example, put NexPress toner into an iGen. The very term “digital” is misleading, because it refers to many disparate processes. Digital is commonly taken to mean toner/laser technology, but in the printing world it may just as readily mean inkjet. Laser and inkjet are about as different as anything can be.

In the digital process, a crucial consideration for color quality is gamut.

Gamut is the range of color a press is capable of reproducing. The wider the gamut, the more colors. Ah, but gamuts of equal size are not equal. One device might be weak in reds; another in blues. Same size gamut; very different results.

Considering a digital press? Here's some really good news. Almost all digital presses have wider color gamuts than the offset process. The bad news? Nobody knows it, because the offset gamut is still the standard in most people's minds.

Dumbed down targets

Each brand (make) and even model of digital press has a different color gamut. All are different from offset. In fact, matching offset means “dumbing down” or shrinking digital's color gamut, as is the case when SWOP profiles are used.

Are you familiar with Pantone's “Color Bridge,” formerly the Pantone “Solid to Process Guide”? Every Pantone color is displayed as spot (actual) color side-by-side with its CMYK process twin.

Like human twins, some colors are dead ringers and others display wide variance between spot and process.

Smart creative and production professionals rely on this guide to determine the feasibility of using process colors to simulate spot color. If the guide shows a poor match, use of that color (or use of 4-color printing) will be avoided.

Good plan. Just remember, the guide is offset-centric. The guidebook itself is printed litho to represent the offset gamut — nothing more.

Colors that show as poor matches might, in fact, be achieved easily on your digital press. You won't know until you try, but your well-meaning client might never give you the chance.

Conversely, colors that show as good matches might not work on your particular digital press. When you struggle and fail to match these colors, your client may conclude that digital is inferior to offset. That would be technically correct, but only for that one color on that one digital press. For a thousand other colors, and on dozens of other output devices, digital leaves offset in the dust.

What's your goal?

If you have both offset and digital presses under one roof, you have a decision to make. A well-planned program of device profiling and color control procedures can assure that all your presses produce consistent, matching color. To achieve this, you must create color profiles for a gamut containing only the colors all of your presses can achieve. In doing so, you'll “dumb down” both your offset and digital presses by narrowing the gamut of each.

Only you can decide if internal device­to­device consistency is more important for your market than the wider color spectrum that your competitors will be achieving using the same equipment.

The second most common method in use today is to profile to “King Offset,” who rules the roost in most integrated shops. This results in the very best offset color possible, but the digital press now endures gamut repression. It is kept from accurately printing colors that are in its own natural gamut but outside of the offset range, and still can't print the colors in the offset gamut that are outside of its own.

I did state that the latter currently is the second most popular choice. Even more common is doing nothing — making no attempt to integrate color controls between print processes.

Choosing the do-nothing option will quickly relegate your shiny new digital press to “color copier” status in the emerging bold new world of digital printing.