Wyniki wyszukiwania - BazTech

1

Investigation of color inconstancy and color gamut changes of printed images depending on the standard illuminants

Spiridonov I., Shopova M., Boeva-Spiridonova R.

Optica Applicata

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2012

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Vol. 42, nr 3

627-641

EN

The main goals of this research are investigation and determination of color balance failure (color inconstancy) of offset printed images expressed by color difference depending on the material used and different standard illuminant conditions. For the experiment, we chose three of the most commonly used in practice illuminants - CIE D50 natural horizon daylight with color temperature 5003 K; CIE F2 cool white fluorescent, 4230 K; CIE A typical Tungsten-filament lighting, 2856 K. A special test form that has been used contains different control strips and measurement components include test chart TC6.02 with about 1000 color patches with different percent combinations of cyan, magenta, yellow and black. The paper, printing inks and printing presses employed in the experiment are some of most commonly used in practice for producing high quality color reproductions. A series of colorimetric and densitometric measurements were performed for different combinations of C, M, Y, K in single, double, triple and quadruple overprint for high tones, middle tones and dark tones. For estimating color balance failure for all the above mentioned measurements there have been calculated the color difference ?E*ab and CMCCON02 depending on standard illuminants CIE D50, F2 and A. For the first time via experimental research in real production conditions (for offset printing method), 3D and 2D presentations and comparison of color gamuts and color gamut volumes for different illuminants were made. According to the results, CIE A has the biggest color gamut volume and CIE F2 - the smallest one. The results obtained are important from scientific and practical points of view. For the first time a methodology is suggested and implemented for examination and estimation of color shifts by studying a big number of color changes in various ink combinations for different illuminants.

2

Wpływ struktury rastrowej reprodukcji triadowej na obszar barw odtwarzalnych

Blachowski K.

Przegląd Papierniczy

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2010

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R. 66, nr 12

735-742

PL

W niniejszym artykule opisano wyniki badania wpływu struktur rastrowych na podstawowe cechy wielobarwnej odbitki wielotonalnej mogące zmieniać wrażenia barwne wywoływane przez światło od niej odbite, przy ustalonych pozostałych parametrach procesu wykonania odbitki. W pierwszej kolejności przeanalizowano wpływ algorytmu rastrowania na cechy kolorymetryczne wielotonalnych pól pierwszorzędowych uzyskanych w różnych technologiach drukowania. Następnie zbadano w jaki sposób różne struktury rastrowe wpływają na podstawowe cechy (długości krawędzi, powierzchnie ścian i objętości) obszarów barw odtwarzalnych (ang. color gamut) wybranego procesu drukowania w różnych przestrzeniach metrologicznych związanych z barwą: CIEXYZ, CIELAB oraz CIECAM02.

EN

The article describes results of the research work on the influence of screening structures on basic properties of halftone color prints which may change colour impressions evoked by light reflected from the prints with other fixed parameters of print preparation process. In the first place, the author analyzes the impact of screening algorithm on calorimetric properties of halftone primary colors obtained by various printing techniques. Next the author examines how different halftone screening structures affect basic properties (edge length, wall surface and capacity) of color gamut of selected printing process in different metrological spaces connected with the color: CIEXYZ, CIELAB and CIECAM02.

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Color calibration method providing uniform distribution of color difference throughout the whole vision gamut

Kretkowski M., Shimodaira Y., Jabłoński R.

Journal of Automation Mobile Robotics and Intelligent Systems

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2009

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Vol. 3, No. 4

213-216

EN

Accurate reproduction of colors requires methods of calibrating a digital camera. In case of a camera which employs filters with spectral characteristics deduced from the color matching functions, a set of reference calibration colors must be used to obtain a conversion matrix between raw data from imaging sensor and colorimetric tristimulus values XYZ, from which the output signal is formed. The XYZ camera used for testing of the presented calibration me thod is capable of acquiring colors accurately in the whole vision gamut due to its filters. However, the well-established color references, like the Macbeth Chart or other similar color checkers, are not entirely sufficient for the calibration due to their enclosure in smaller color gamut (HDTV - High Definition Television) than the whole vision gamut. The presented method is based on choosing the calibration colors by their spectral distributions, which are related with the spectral characteristics of the filters. The obtained result was found to be ?E=1.57 for the designed colors.