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Dynamic optimization

Jan 1, 2009 12:00 AM


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We recently spoke with Elie Khoury, a color management pioneer as well as the founder and president of Alwan Color Expertise (Lyon, France). See www.alwancolor.com.

Can you give us an overview of Alwan's products?

CMYK Optimizer was originally created to help users standardize and optimize CMYK separations. Today, it is as much a quality assurance as a color management tool. It performs a comprehensive preflight analysis of the image and page components of a job, based on the output path, prior to doing color conversions. Thus color is managed according to all factors influencing color appearance in the final print, including the output devices involved, the color content and the actual color components of each page.

CMYK Optimizer creates different device link profiles based on the content of a job, which improves throughput in the workflow. It ensures optimized production speed and production readiness especially for incoming files that include lots of complexity in the source data, such as content created with numerous applications — such as Word, Illustrator and Photoshop — and involving diverse data sources, such as image databases. When the same file is destined for both offset and digital printing, processing parameters are simple to update because they are based on standard tools: Adobe PDF and ICC profiles.

How does color standardization and color separation optimization work?

In the PDF environment, we perform PDF Color Analysis where input PDFs are preflighted and parsed prior to any correction. Corrections are content dependent and are therefore not systematically the same for all PDFs as is the case with many other color servers.

We also employ dynamic Total Area Coverage (TAC) output. TAC is content and output profile dependent. We analyze images and tints for ink coverage and surface and identify relevant output process capabilities in high-density regions. Optimal output TAC for each color object is then calculated accordingly. Dynamic DeviceLinks profiles are generated on the fly to ensure optimal content color management.

How is ink consumption reduced?

There are two mechanisms within CYMK Optimizer. GCR, available in the Press version, is a conventional way of replacing some of the CMY contribution to the printed color with black. Dynamic Black, available in the ECO version, is our unique way of defining the optimal CMYK values and minimum ink requirements to print a color, given the content nature (tint, image and text) and characteristics (dark, neutral, saturated, light color) and the output press capabilities.

What are Dynamic DeviceLinks?

This is CMYK Optimizer's core technology. Press color management should reconcile two goals: colorimetry and printability. Colorimetry concerns matching source colors on press, while printability relates to adapting files color data to the press capabilities to increase the process efficiency and productivity.

RIPs, color servers and even closed-loop systems typically can achieve one goal, but seldom both. Alwan Dynamic technology, which is based on files and output process analysis, can achieve the correct colors at minimum cost for any and every job.

How is the TAC determined?

TAC defines the maximum amount of ink that can be put on a given paper and press to get the deepest possible colors and blacks. Therefore, TAC influences print contrast. The higher the TAC, the higher the contrast, but there's also a greater risk of excessive ink which can result in ink set-off, paper wrinkling and even paper breaks on web presses.

For a given output process and ICC profile, CMYK Optimizer automatically determines the optimal TAC to print an image with maximum contrast, without these production risks.

What if a PDF file contains images from different color spaces?

CMYK Optimizer can handle multiple color-space content. Each PDF object is analyzed in terms of color space, separation and rendering properties. Multiple RGB and CMYK in source files, even with transparencies, aren't a problem. CMYK Optimizer manages these sources automatically.