DICE test target now incorporated into the Zeutschel OS QM Tool.
Zeutschel have recently incorporated the DICE target from Golden Thread into the OS QM Tool. This target is designed to allow scanner performance measurements. It can be used to measure illumination uniformity, spatial distortion, resolution variability, De and Noise over the target area. The target is widely used in the US and referenced regularly in the FADGI standard. Other test targets that can be utilised are UUT, CCSG, CC Classic, it 8, 7/2, Q13 and Q-62
The OS QM Tool is a software tool from the world-renowned book scanner manufacturer, Zeutschel that is usually associated with the UTT test chart and is capable of both evaluating test charts and measuring certain aspects of quality, for compliance with various standards. It can also be incorporated into the Omniscan scanning software to ensure quality is checked and achieved during the scanning process. By scanning a test chart, all relevant parameters can be captured with only one scan. The OS QM Tool can analyse these parameters and determine within a few seconds whether an image meets the required standard. This makes it possible to automate quality control and to conduct it ´in-line´ with the production process. It no longer has to run parallel to production as a separate process. Omniscan can be set so the operator has to capture the UTT test chart after a certain amount of scans, the image is quickly analysed, and the results displayed. This significantly reduces the risk of time-consuming repeat digitisation of larger batches, due to misalignments of the scanner.
The UTT test charts are available as A3, A2, A1 and A0. The larger ones are multiples of the A3.
As the requirement to meet a specific standard increases the easiest way to achieve this and monitor it is with the OS QM Tool. It is also a very useful tool to monitor the output of your images so that a constant quality is maintained.
The following elements can be analysed within the OS QM Tool software:
MTF – Modulation Transfer Function
On an A3 UTT Target you will find nine Slanted Edges targets. These Slanted Edges will be used in the MTF-check
Modulation Transfer Function (MTF) is a measurement of the contrast difference between the original image and the digital image. MTF is defined as the modulation ratio of the output image and the ideal image. Spatial Frequency Response measures the imaging systems ability to maintain contrast between increasingly smaller image details. Using these two functions, an accurate determination of resolution can be made as it relates to sampling frequency.
The colour distance Delta E (written also dE or ∆E) is the distance between an ideal value and a measured value in a colour space. On an A3 UTT Target you will find two colour fields consisting of 27 colour patches each. These colour fields are used to conduct the ∆E-check against the data provided within the test chart.
On an A3 UTT Target you will find three horizontal and three vertical grey bars (see Image 1) and four grey scales containing 20 fields each (see Image 2). The grey bars and grey scales will be used whilst completing the noise check. It is also used to determine dL*, dC* and gain modulation, where dL* is the absolute value of the field, dC* colour cast in those neutrals and gain modulation is the size of the step between those steps
The OECF ((opto-electronic conversion) function) check of a scanned UTT can be carried out on the grey bars and/or the grey scales.
For the homogeneity check, both the lighting and lens performance contribute to this measurement. Ideally, there should be a perfectly even recording of all white square patches over the entire test chart.
The geometry check of a scanned UTT is to check the relationship between the media and sensor. Critically important to faithful reproduction of an original is the management of geometric distortion in image capture. Some standard amateur photographic lenses are poorly corrected for this and create images which exhibit significant distortion, even under ideal conditions. If the imaging system is not correctly aligned, other distortions are introduced to the image as well.
All these results can be displayed in a simple graphic, as below, or as data.
The length of the bars complies with the quality of the image, the longer the better. Green bars mean the test was successful, red bars signal a failure. The yellow marks correspond with the warning thresholds.
A comprehensive video explaining the functionality of the Zeutschel OS QM Tool is available at https://www.youtube.com/watch?v=a3pHnYyTdyI