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Picture:
Quality control at a glance.
The universal test target (UTT) is to revolutionize quality management in mass digitization.
Ensuring consistently high quality during the demanding mass digitization of library and archival collections thus far has been very labor-intensive and time-consuming and, consequently, expensive and error-prone. Furthermore, there still is no practice that would ensure the comparable application of national and international standards.
With its OS QM Tool, Zeutschel now offers software that makes it possible to analyze almost all relevant quality characteristics through the analysis of a single scan and to evaluate these on the basis of selectable standards. Moreover, the direct integration into the scanning software allows you to ensure high quality already during the scanning process.
High labor input
High-quality digitization of extensive collections of historically relevant documents is increasingly becoming part of the daily routine tasks at libraries, archives, and museums. In order to generate true-to-original digital reproductions of the often one-of-a-kind historical originals, overhead scanners of the newest generation are used.
These devices must meet very high requirements. Consistently excellent display quality is just as indispensible as a high work efficiency based on an extensive automation of operational procedures. In order to detect changes in the image quality caused by mechanical, electronic, or optical misalignments during the scanner´s operation, technical staff until now had to carry out and analyze test scans at regular intervals using several calibration targets (comparable to test patterns on TV).
Additionally, this comparatively time-consuming process could result in large parts having to be rescanned. Quality management was also hampered by the lack of generally accepted and standardized parameters for a clear-cut assessment of the image quality. As a result of that fact, procedures with proprietary assessment criteria, such as those established by the National Library of the Netherlands in The Hague within the scope of the so-called “Metamorfoze guidelines,” turned into a de facto standard for many similar library projects all over Europe.
Creating automated workflows
Building on the acquired wealth of experience and the international recognition, those in charge at the Dutch library decided to further develop the process of quality assurance in digitization projects and to broaden the basis as well.
In collaboration with the Association of Multimedia Information Processing (FMI e.V., Fachverband für Multimediale Informationsverarbeitung e.V.) , the National Library of the Netherlands and the company Image Engineering, a research and test laboratory for image analysis software – the initiative has now introduced the universal test target (UTT) specifically developed for use in the library environment. The calibration target contains different gray-scale and color representations that provide extensive possibilities for image quality assessment.
“With the aid of the innovative test chart, all relevant parameters can be captured with only one scan. A corresponding tool can analyze these parameters and determine within a few seconds whether or not an image meets the required standard. This makes it possible to automate quality control and to conduct it ´in-line´ during the production process. It no longer has to run parallel to the production,” Volker Jansen, Development Manager at Zeutschel, explains.
New UTT analysis tool
Using a quality management (QM) solution developed by Zeutschel as an example, the degree to which the automatic analysis of the UTT with analysis software in particular can change the quality assurance of future digitization processes becomes clear. Zeutschel´s ´OS QM Tool´ runs on Microsoft Windows operating systems and can be used independent of the scanner.
In contrast to previous image analysis software designed for laboratory use by highly qualified personnel, this software is consistently geared to the production processes taking place during mass digitization in the library environment as well as the specific requirements regarding the staff there. Limit values for quality-relevant factors such as sharpness, resolution, noise, etc., can be defined in advance on a project-specific basis and saved in parameter files. After scanning the UTT, the file created in the process is automatically analyzed, the measured values are compared with the predefined limit values, and the results are issued in the form of a result log on the screen as well as in a file.
“With regular use of the UTT, for example after 100 or 200 scans, the image quality of the digitized media can continuously be checked that way. This significantly reduces the risk of time-consuming repeat digitization of larger batches due to misalignments of the scanner,” said Volker Jansen.
Volker Jansen expects an additional increase in efficiency in quality control through the integration of the UTT analysis tool into Zeutschel´s existing capture software “OmniScan.” In this case, the result log is to be evaluated – also automatically – by the scanning software. If the predefined limit values are exceeded, the scanning software can even supply the operator with concrete information regarding possible causes of errors and recommendations on how to correct them, which would considerably accelerate potentially necessary readjustments. According to Jansen, such a combined solution for Zeutschel scanners will be available as an option in the near future.
UTT is an open standard; the technical specifications are freely accessible on the UTT website, which was recently set up. UTT calibration targets can be obtained from Zeutschel, among others. According to Volker Jansen, the manufacturers´ as well as the users´ response to the initiative has been consistently positive. “We have seen approving reactions from France, England, and the USA, among others. The responsible ISO specification committee has already reacted, too, and established an ad hoc commission dealing with the UTT,” said Jansen.
The possible acceptance of the UTT as an ISO-specified standard could bring the initiators closer to another long-term objective: the integration of UTT-based quality control into the complete solutions for production flow control used in the library environment.
http://www.kb.nl/
http://fmi-ev.de/
http://www.zeutschel.de/
http://www.image-engineering.de/
The Universal test target (UTT)
The calibration target provides various color and gray-scale patterns and gradients that allow a comprehensive analysis of all parameters relevant for image assessment. For example, the examination of homogeneity of white and gray is supported, as is the examination of image geometry or image distortion. Continuous scales in millimeters and inches allow checking the nominal resolution in X and Y direction. Color fields facilitate the generation of ICC profiles, give information about color fidelity, and allow checking the color space. Using a gray scale, the noise performance and the signal-to-noise ratio can be determined in addition to a measurement of the opto-electronic conversion function (OECF). The target also permits the checking of the resolution up to 18 lp/mm as well as the determination of the modulation transfer function (MTF) in accordance with ISO 160-67-1 up to a maximum of 1,200 DPI.
The UTT has a basic size of DIN-A3 (420 x 300 mm); by means of duplication, the format sizes A2, A1, and A0 can be analyzed as well.
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