Spectral gamut prediction and mapping
Partner: TUD, Darmstadt, Germany
Supervisor: Dr. Philipp Urban
Sepideh Samadzadegan carried out her research through her PhD studies at Technische Universität Darmstadt in Darmstadt, Germany.
Her research focuses were on printing the spectral and specular properties of surface appearance leading to colour and gloss reproduction. In general, printing material’s appearance properties beyond their colour, such as gloss and texture, is essential in applications in which accurate material appearance reproduction is required. By the emerge of 2.5D and 3D printing technologies, a door has been opened for conducting more research on materials appearance reproduction such as their glossiness and texture.
Using multi-channel (CMYKRGB) printing systems, the spectral reproduction in terms of spectral gamut mapping and separation was studied for the ideal aim of obtaining a colorimetric-match between the original image and its spectral reproduction under a variety of illuminants. As the result, an existent spectral reproduction method was improved by obtaining colorimetric accuracy across a set of illuminants and reducing the generation of artifacts.
In order to control the specular reflection properties and thereby the surface gloss appearance, 2.5D printing systems were utilized. By controlling the drying time between layer-by-layer deposited colorant combinations, different surface gloss levels from very matte to semi matte were generated. For printing surfaces with higher gloss appearance, from semi matte to almost high gloss, varnish-halftoning strategy was used. In this approach, first a colour layer was printed and then a varnish-halftoned layer was printed on top. Psychophysical experiments were conducted in order to correlate the printed gloss values to visually perceived gloss magnitudes. This information can be used for the future aim of building a perceptually meaningful gloss space and performing colour-gloss gamut mapping. Moreover, different samples in three texture types, various texture elevations and gloss levels were printed. Another psychophysical experiment was conducted in order to investigate the interrelation between printed gloss and texture.
Publication and Dissemination
- Samadzadegan, S. and Urban, P. (2013), Spatially resolved joint spectral gamut mapping and separation, in ‘Color and Imaging Conference’, number CIC21, Society for Imaging Science and Technology, pp. 2 − 7.
- Baar, T., Samadzadegan, S., Ortiz Segovia, M. V., Urban, P. and Brettel, H. (2014), Printing gloss effects in a 2.5D system, SPIE Electronic Imaging, San Francisco, CA, USA.
- Samadzadegan, S., Blahova, J., Urban, P., (2014), Color-Printed Gloss: Relating Mea- surements to Perception, IS&T Color and Imaging Conference, Boston, Massachusetts, USA.
- Samadzadegan, S., Baar, T., Urban, P., Ortiz Segovia, M. V., Blahova, J., (2015), Controlling Colour-Printed Gloss by Varnish-Halftones, SPIE Electronic Imaging, San Francisco, CA, USA.
- Samadzadegan, S. and Urban, P. (2015), Spatio Spectral Gamut Mapping and Separation, Journal of Imaging Science and Technology, Pages: 58-69.