3 February 2014 Evaluation of perceptual resolution of printed matter (Fogra L-Score evaluation)
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A new method has been developed to address the objective evaluation of perceived resolution of printed matter. To achieve this, a psychophysical experiment has been designed and conducted that ranked typical test prints representing the manifold of printing processes and substrates. A scanner based method has been developed that computes a score value between 0 and 100 termed Fogra L-Score. It is based on the idea to identify a predefined signal in an image (print). The predefined signal is a perfect representation of the “perceived resolution domain” by means of a test target (RIT ConRes-target) that covers systematic variations of the two governing parameters of perceived resolution namely contrast and spatial resolution. The printed images to be evaluated have been scanned and pre-processed. The level of closeness between the reference (digital representation) and the printed matter (scanned print) have been determined by a 2-dimensional normalized cross-correlation (on the CIEL*-channel). The resulting correlation coefficients have been compared against findings of the performed psychophysical experiment. Finally a framework will be presented that also allows for spatial filtering to address different intended viewing distances as well as chromatic test charts. Publisher’s Note: The first printing of this volume was completed prior to the SPIE Digital Library publication and this paper has since been replaced with a corrected/revised version.
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Thomas Liensberger, Thomas Liensberger, Andreas Kraushaar, Andreas Kraushaar, "Evaluation of perceptual resolution of printed matter (Fogra L-Score evaluation)", Proc. SPIE 9016, Image Quality and System Performance XI, 901606 (3 February 2014); doi: 10.1117/12.2037262; https://doi.org/10.1117/12.2037262


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