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Reworking the Rainbow

(March 1999) posted on Mon Dec 13, 1999

Learn about the issues in color control and proofing that printers face when producing ceramic decals with process-color separations.


By Jere Williams

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The blue sky would probably exceed the gamut of this ceramic-color combination in both saturation and brightness. If you increase the percentages of magenta and cyan equally to boost the saturation, the sky will darken and appear stormy. If you decrease the cyan and magenta equally to preserve the brightness, the sky will appear more white and, thus, less "clear." If you move the hue of the sky closer to either magenta or cyan, you may be able to increase both the saturation and brightness. But an increase in cyan will make the sky appear more blue, as it would at midday, and an increase in magenta will move the sky toward the pinker cast of the morning sky.

Any of the previous compromises will limit the color range within the sky, thus reducing the sky's apparent depth and the perceived separation between the sky and the foreground. Additionally, the gentle transition in saturation of blue from a richer appearance in the upper sky to a paler appearance at the horizon may also be lost. In the end, the compromises you settle on will depend on what is happening in the rest of the image and what is important to the client. Pitfalls in proofing

<P>While it would be easier and more economical to resolve color-reproduction questions with clients by using some form of prepress proof, rather than a proof run on press, currently no accurate prepress color-proofing system exists for glass and ceramic decorators. Again, the problem stems from the limited gamut ceramic inks provided and the fact that fired and unfired colors appear quite different.

With conventional printing, the same film or digital separations used for production can be used to render accurate prepress proofs, and the process colors used for each layer of the proof can be closely matched on press for hue, saturation, and density. When proofing conventional prints, the typical workflow generally begins with the digital artwork, which is output to a contract proofing system. The proof print is then submitted to the client for approval. If the contract proof is rejected, adjustments to the original artwork can be made, and a new proof can be quickly generated and presented to the client.


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