To improve color reproduction, many printers today use extra colorants, in addition to the traditional four inks (Cyan, Magenta, Yellow and Black). Adding the complementary colorants (Red, Green and Blue) increases the gamut of reproducible colors, while lighter versions of the primary inks can be added to reduce graininess and dot visibility. Using more than three inks introduces colorimetric redundancy in the color separation process, because different ink combinations can reproduce the same target color. When additional inks are introduced, this redundancy rapidly increases, and it is thus crucial to introduce additional constraints in the color separation process, to improve determinacy and to optimize different aspects of print quality. This study focuses on an analysis of the redundancy in the color separation process for an 11-ink printer. It is investigated how the extensive colorimetric redundancy can be utilized to select optimal ink combinations to meet the, sometimes contradictory, criteria of color accuracy, graininess and ink consumption. Analysis of the results of applying different criteria in the color separation process shows that the result heavily depends on the selected criterion. For example, prioritizing graininess will improve print quality by reducing dot visibility, imposing the use of lighter inks, but it will also increase ink consumption.
The Mottle analysis method is widely used to describe ISO 13660 and improved by ISO 24790. However, this method showed not enough satisfied correlation for ours. In this paper, we propose a new method for measuring effective noise analysis in solid area. We will name it as 'Solid-Mottle'. It is phenomenon of printing optical-density non-uniformity at solid-black, and it is occurred on laser-printers. The purpose of present paper is to offer an analysis of Solid-Mottle defect, test pattern and method for measuring. Quantified Solid-Mottle is measured based on psychophysical experiment. Parameter A and JNDmottle is determined by human experiment. By conducting five-fold cross-validation, the strong correlation was obtained between the proposed method and perceived scales: the correlation coefficient r is 0.94, RMSE (Root Mean Square Error) is 0.34, respectively. In addition, the F1-measure score is 0.92 by SVM (Support Vector Machine) approach.
In 2013 the European Metrology Research Program (EMRP) funded a 36 months research project, "Multidimensional Reflectometry for Industry, xD-Reflect", to investigate the macroscopic optical properties related to visual appearance of modern surfaces. During the three years duration of the project, over in August 2016, several visual experiments have been performed to investigate appearance of materials with goniochromatic and sparkling effects. Metal-flakes produce shiny effects whose definitions, quantities and metrological characterizations are still under development. This paper relates to the measurement and visual estimation of graininess and brightness perceived of metal flakes achromatic pigments materials. The subjective ranking on graininess and brightness of three different sample sets different for particles shape (silver dollar and corn-flakes) and dimension, were compared under similar viewing conditions on two commercial lighting booths, one based on LED lighting and one on fluorescent light, both reproducing CIE D65 illuminating conditions. The subjective rankings were compared with the graininess measured with a Byk-Mac instrument and the luminance measured with a luminancemeter in the experimental conditions inside both lighting booths. The performances of the two lighting cabinets and of the two different flake shapes were also compared. The results are useful both for shops lighting arrangements and industrial panelist investigations.