The Expanded Gamut Conundrum

As our industry accelerates through this decade, one thing is certain; print runs & lead times continue to shorten. That’s a fact, not a fad. To stay competitive, printers in turn must explore innovative and competitive ways to maximize profits by reducing downtime, ink & substrate waste.

The age-old problem in tackling the above is compounded by yet another variable; Consumer Product Companies (CPC’s). They're constantly demanding more colorful, complex and innovative designs to entice consumers into that split-second purchase. Look at any candy or snack package and you’ll see less solid colors and more extensive use of multi-colored vignettes and eye-popping graphics.

CMYK History

Did you know the first color reproduction was produced by the James Clerk Maxwell (Scotland) in 1861? Below is a schematic of how they made color separations back in 1959. Over 160 years later and nothing’s really changed... paper, transparent inks and trillions of dots enable the gamut of process colors we see in print today.

Color Separation Photography – ? 1959 Graphic Arts Technical Foundation, Inc.

Digital Color Reproduction

Our CMYK forefathers’ color separation inventions were pure genius. They discovered white light is reproduced by the equal admixture of red, green and blue (RGB) light. Colored light is reproduced by the unequal admixture of RGB light. Take a look at your monitor under a magnifying glass. RGB phosphors (pixels) are juxtaposed to create the "illusion" of 16.7 million colors. This is called additive color reproduction.

In print, cyan, magenta and yellow (CMY) inks and halftone dots overlap to create varying shades of hues. To reproduce red, green and blue hues, the process overprints any two C, M, or Y inks. Therefore, CMY is complementary to RGB. This is called subtractive color reproduction. Black (K) ink is also required to add contrast, detail and density.

In theory, overprinting 100% CMY should produce a neutral black. In practice, it reproduces a dark brown due to reflection/absorption deficiencies in the process inks themselves, hence the need to imbalance CMY (i.e. 50c 41m 41y) to reproduce a neutral gray.

Please note that in both additive and subtractive systems, I’ve used the term “digital” to define color reproduction via pixels/dots using RGB or CMY primary colorants. Now comes the not so good news for printers. Consumers are attracted to vivid, saturated colors in packaging (and the CPC’s know it)! However, the CMYK process can only reproduce a limited color gamut, far smaller than the RGB gamut on your monitor. More often than not, colors in packaging designs fall "out–of–gamut".

What is a Gamut?

Gamut literally means; “a graduated series running from one possible extreme to another.” In music, an instruments sound gamut is defined by its highest and lowest note (pitch).

In print, a CMYK gamut is defined by:

1. Observer.
2. Light source.
3. Substrate.
4. CMYK pigments and transparent inks.
5. Solid ink densities (S.I.D's).
6. Single color ink films and their secondary overprints.
7. The print medium (i.e. offset, digital, inkjet, flexography, gravure & screen printing).

"Colors" are reproduced within this gamut utilizing another ingenious invention – halftone screening. Dots create the illusion of tones or gradations. A process color has a dynamic range of 100 gray levels (i.e.1%–99% dots).

Color scientists have identified approximately a third of visible colors fall outside the CMYK gamut. For example, bright oranges, lime greens, saturated reds, vivid blues and violets. Hence, the need to print additional spot colors in packaging. Spot colors are premixed inks which occupy separate decks on the press. They are not derived from additive or subtractive color models and are simply a collection of arbitrary colors that graphic designers choose from various swatch books.

So how can printers stay competitive by delivering unlimited digital colors (beyond CMYK), shorter lead times, greater consistency and most importantly, still make a profit? Imagine a 100% digital printing world whereby we never change inks (or anilox); just change the plates, sleeves and/or gravure cylinders.

Expanded Color Gamut (ECG) Benefits

– Eliminate spot colors.

– Richer, more saturated, eye-popping graphics.

– Color consistency and repeatability.

– Combination SKU’s in one print run.

– Reduce make-ready times.

– Reduce ink inventories, solvent and substrate waste.

– Reduce anilox inventories (i.e. constant anilox ink volumes for each process color).

– Environmental sustainability.

Wow! Sounds to good to be true, right? Why isn’t everyone jumping on the bandwagon? While many XG systems exist with their own methods and colorants, CPC’s remain hesitant to commit because there’s still no ISO ECG standard beyond CMYK. It’s uncharted waters. In other words, CPC’s realize their brands won’t look the same globally unless they utilize the same XG system in Sydney, New York or Tokyo etc. Moreover, printers are reluctant to change. Having dealt with copious spot colors over the last six decades, it’s like asking them to convert from gasoline to electric engines. XG printing isn't for the fainthearted. It is a disruptive technology that's here to stay.

The ECG Pioneers

The concept of expanding the CMYK gamut isn’t new, here are several pioneer's US patents: 3,555,262 (Shimada 1971) ? 4,812,899 (Küppers 1989) ? 5,528,377 (Hutcheson 1996) ? 5,687,300 (Cooper 1997) ? 5,734,800 (Herbert & DiBernando 1998) ? 5,751,326 (Bernasconi 1998).

Each inventor disclosed their separation method and the extra process colors used. For example, +OGV, CMY or RGB. I’d like expand on the logic behind how/why I developed a +RGB color separation system (5,751,326).

As outlined earlier, CMY is complementary to RGB and all visible colors are derived from RGB light (additive color). In color reproduction, there’s no such thing as “color” per se. Image capture devices (scanners, cameras & iPhones etc.) are color blind and can only record "gray levels" of data (typically 10-bit = 1024 gray levels per channel compressed via a RIP to 8-bit = 256). This is achieved using RGB CCD (Charge-Coupled Device) technology that filters the RGB (wave lengths) of light. Red light transmits red & absorbs blue & green (–GB = R). Green light transmits green & absorbs red & blue (–RB = G). Blue light transmits blue and absorbs red & green (–RG = B). White light transmits red, green & blue light (+RGB = white). Black (no light) absorbs red, green & blue (–RGB = black).

CMY+RGB

If RGB is complementary to CMY, then it made sense (to me) to add red, green & blue primaries to augment the gamut deficiencies in CMYK. For example, orange isn't a primary color, it's a secondary color and can be reproduced by overprinting 100r+100y (60° hue angle). What's also unique about RGB is (just like on your monitor) 50r, 50g, 50b reproduces a neutral gray (chroma <2). To demonstrate 7-color separations visually (Adobe Illustrator & Photoshop), please feel free to download this CMYKRGB test form from the Dropbox link below.

CMYKRGB Test Form

Also enclosed are the technical specifications to conduct your own CMYKRGB print trial. Pigments (color index numbers), S.I.D’s, T.V.I’s, screen angles & print sequences are defined for Offset, Flexo & Gravure. Upon request, RGB ink recipes for HP Indigo can be provided. Moreover, you may also like to print this test form (no copyright) with your own ECG inks to help compare expanded gamuts. Please feel free to contact me at [email protected] with any questions (or post them in the Linkedin XG7 group). I look forward to sharing your results.

ISO ECG Standards?

To conclude, our industry follows ISO CMYK standards that have been ratified for digital, offset, flexography & gravure.

ISO/DTS 21328.4 – Guidelines and Requirements for Multicolour (CMYKOGV) Print Characterization is currently a Committee Draft (CD) and has just been approved for Draft International Stage (DIS). Stage (40) is the next inquiry stage. An ISO standard takes approximately three years to be ratified.

In the meantime, the CPC’s conundrum continues regarding which ECG system(s) their suppliers should use? Without ISO ECG standards, expanded gamut printing will remain a hybrid niche market. Is it plausible to ratify an ISO ECG standard? Or will ECG remain a collaborative artistic approach between the CPC, designer and printer?

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