Tired of tying up presses and personnel as you try to emulate the output of your printing equipment? Discover some powerful methods you can use to improve color matching with any CMYK inkset, substrate, or line count on any printing device.
By Mike Ruff
The secret sauce in the G7 method is that it delivers a constant appearance in terms of gray balance and neutral density— regardless of which colorants you use or how you apply them to the substrate—without the need for additional color management. When the dot gain is too high or too low, the calibration method just lowers or raises the gain to achieve a specific neutral tonal value, meaning the color of a file is accurately represented with no color cast. Solids that are too high are adjusted at the midtone. Solids that are too low are adjusted at the midtone. That way the appearance is neutralized in most of the image.
G7 is therefore the first calibration methodology to offer cross-media grayscale consistency, which means files are more easily and safely re-purposed from litho to flexo, litho to screen, digital to screen, etc. Even though G7 alone does not attempt to control color accuracy, the fact that it does control neutral gray tones without ICC profiles is a major step toward a universal standardized definition of printed appearance that can be applied to all imaging methods.
Hybrid curves offer another approach to matching color device to device by targeting midtone neutral absolute density values. Hybrid curves are very similar to what color-management software does in a relative rendering intent, except for chasing ink hues. The curves are created using absolute density values, as well as dot-gain values, to closely match an intended color target. Absolute density is used in the middle of the curve, and dot percentage is targeted in the highlights and shadows of the curve. Printers are using this technique in litho, flexo, screen, and digital. The closer the numbers are to matching the intended target, the closer the match.
But just like relative rendering intent in color management, when the substrate is dramatically different, we allow the tonal percentages below 25% to deviate from the target. We risk losing image detail when we try to completely correct this problem (Figure 3).
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