Ensuring quality and accuracy
The trend in newspaper printing for better control over colour is being fueled by a need to diversify. Semi-commercial products, hybrid heatset/coldset newspapers and publications geared to attract advertisers - such as lifestyle supplements - are now commonplace. To help newspaper printers penetrate into high-quality colour advertising markets, opening new revenue streams while reducing manpower costs and waste with added capabilities, QuadTech has responded with the colour control system with AccuCam.
Illustration: Test results showing how to achieve and maintain fine colour (the point when eighty percent of all ink keys are within 0.02 absolute delta density of target) with far greater consistency than manual colour control.
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he inline, image-based, closed-loop colour control system with AccuCam delivers the necessary accuracy and consistency, optimizing control over an entire image by comparing values of the live image with target aim points derived from the pre-press file. As a result, the system eliminates the need for unsightly colour bars and gray scales, making more space available for editorial or revenue-generating advertisements. Unlike RGB-based alternatives that only compare sample areas from the image, the CIELAB-based QuadTech system obtains target values from the entire image. Using L*a*b* data, it overcomes the challenges of holding gray scale tolerances and ensures accurate corrective steps are taken to maintain targets.
The control system supports webs of up to 96 inches (2436 mm), and a maximum of 36 towers. It also features a unique six-channel spectral sensor for each surface. The sensors detect discrepancies and issue ink-key adjustments, maintaining optimum live-image consistency. The AccuCam’s sensor also allows for inline inspection for plate verification, transposed colours, wrong pages, scumming defects, and more - delivering higher quality printed product and additional labour savings.
In tests carried out by QuadTech, the AccuCam proved capable of waste reduction, and of maintaining much improved quality consistency, when compared to manual colour control. In manual control situations, where an operator reviews a sample printed edition, one page at a time, this level of accuracy is rarely achieved - and deteriorates over time due to human error and press characteristic drift. The QuadTech system maintained an ink-key adjustment rate exceeding 1600 per print run, over 40 times as great as manual mode rates.
Requiring minimal manual input, the colour control system with AccuCam is an ideal solution for hectic scheduling environments, where production downtime must be kept to a minimum. Its intuitive user interface has minimal screens and buttons, and little navigation is required to access colour data overviews during production. Furthermore, OptiGuard, an anti-contamination device that ventilates low-pressure air across the lens, ensures clean image capture at all times. Due to the system’s user-friendliness, operators have more time to focus on other essential added-value tasks. The system operates through QuadTech’s ICON platform, which runs multiple press controls from a single operator interface.
“The AccuCam is a result of several years’ intense product development, answering the newspaper industry’s need for a low-maintenance, cost-effective and labor-saving alternative to RGB-based or manual colour control, without compromising on accuracy. This development makes the newspaper industry well-positioned to diversify into high-value colour advertising markets,” commented Karl Fritchen, president of QuadTech who have an established newspaper presence, with over 1320 register and ribbon control systems installed world-wide on newspaper presses in the last twelve years.
