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(May 2007) posted on Thu May 24, 2007


By Mike Ruff

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Dot-gain curves in highlights and extreme shad­ows and density curves in the quarter-tones, midtones, and shadows correct the color but won’t sacrifice detail of the image. G7 does the same thing, and it also creates a visual appearance of ISO 12647-2. Should the solid colors and substrate differ from the intended target appear­ance, the NPDC of G7 will ignore the highlights and solids and correct the bal­ance of the image to produce a consistent color appearance. If your target’s solid densities and substrate are the same as your print, then dot-gain curves and hybrid curves will yield almost identical numbers. However, if the color of the ink and/or the substrate are dramatically different from the color target—possibly an international color standard—then there’s a big advantage in using both density and dot-percentage data com­bined to create a hybrid curve for the printing device. Doing so corrects the effects of colored substrates like styrene, corrugated plastic, gray cast vinyl, and foam boards. When we apply both sets of data, we adjust the color in the high­lights and shadows for better detail with a dot-gain curve and adjust the quarter tones, mid-tones, and three-quarter tones for more accurate color with an absolute-density curve. Therefore, when we mix the two different methods of curving our tonal range, we can have great de-tail and more accurate color. We create a hybrid curve.

