Image Sampling with Quasicrystals

We investigate the use of quasicrystals in image sampling. Quasicrystals produce space-filling, non-periodic point sets that are uniformly discrete and relatively dense, thereby ensuring the sample sites are evenly spread out throughout the sampled image. Their self-similar structure can be attractive for creating sampling patterns endowed with a decorative symmetry. We present a brief general overview of the algebraic theory of cut-and-project quasicrystals based on the geometry of the golden ratio. To assess the practical utility of quasicrystal sampling, we evaluate the visual effects of a variety of non-adaptive image sampling strategies on photorealistic image reconstruction and non-photorealistic image rendering used in multiresolution image representations. For computer visualization of point sets used in image sampling, we introduce a mosaic rendering technique.Comment: For a full resolution version of this paper, along with supplementary materials, please visit at http://www.Eyemaginary.com/Portfolio/Publications.htm

Stippling by Example

In this work, we focus on stippling as an artistic style and discuss our technique for capturing and reproducing stipple features unique to an individual artist. We employ a texture synthesis algorithm based on the gray-level co-occurrence matrix (GLCM) of a texture field. This algorithm uses a texture similarity metric to generate stipple textures that are perceptually similar to input samples, allowing us to better capture and reproduce stipple distributions. First, we extract example stipple textures representing various tones in order to create an approximate tone map used by the artist. Second, we extract the stipple marks and distributions from the extracted example textures, generating both a lookup table of stipple marks and a texture representing the stipple distribution. Third, we use the distribution of stipples to synthesize similar distributions with slight variations using a numerical measure of the error between the synthesized texture and the example texture as the basis for replication. Finally, we apply the synthesized stipple distribution to a 2D grayscale image and place stipple marks onto the distribution, thereby creating a stippled image that is statistically similar to images created by the example artist

[Re] Weighted Voronoi Stippling

International audienceA reference implementation of "Weighted Voronoi Stippling", Adrian Secord. In: Proceedings of the 2Nd International Symposium on Non-photorealistic Animation and Rendering. NPAR ’02. ACM, 2002, pp. 37– 43

Generation of automatic stippling illustrations from photographs for documenting archaeological pieces

[EN] Hand-made stippling has been used frequently in the process of drawing illustrations for documenting archaeological pieces. This is due to the fact that this technique represents in an efficient way shapes, tones, and textures, by means of distributing dots on the paper. The process of stippling has needed traditionally the ability of an artist, who usually produces the illustration from photographs. In this paper, a program that generates stippling illustrations of high quality is presented. The developed interface makes possible that any user can generate illustrations without the need of artistic abilities. The program is able to work in realtime, allowing the user interacts with the program. We have developed several artistic techniques in high level tasks that allow to improve the final results.[ES] El punteado manual se ha utilizado frecuentemente en el proceso de ilustración para documentar piezas arqueológicas. Esto se debe a que esta técnica es capaz de representar de forma eficiente formas, tonalidades y texturas mediante la distribución de puntos en un papel. Estas ilustraciones requieren las habilidades de un artista, el cual utiliza fotografías para realizarlas. En este artículo se presenta un software que genera ilustraciones punteadas de alta calidad de forma automática. La interfaz desarrollada hace posible que cualquier usuario pueda generar ilustraciones sin la necesidad de habilidades artísticas. El programa trabaja en tiempo real permitiendo al usuario interactuar con el mismo. Hemos implementado varias técnicas empleadas por artistas como simples tareas de alto nivel que mejoran los resultados finales.Authors thank the collaboration of the illustrator Elena Piñar. Thanks to the Ministerio de Educación y Ciencia of Spain for the projects TIN2007-67474-C03-02 and TIN2007-67474-C03-01, which have partially funded this work.Arroyo, G.; Martín, D.; Luzón, MV. (2011). Generation of automatic stippling illustrations from photographs for documenting archaeological pieces. Virtual Archaeology Review. 2(3):59-64. https://doi.org/10.4995/var.2011.4606OJS596423SECORD, A. (2002): "Weighted voronoi stippling". In Proc. of NPAR, ACM Press, pp. 37-43. http://dx.doi.org/10.1145/508530.508537DEUSSEN O. et al. (2000): "Floating points: A method for computing stipple drawings". Computer Graphics Forum 19, pp. 40-51. http://dx.doi.org/10.1111/1467-8659.00396HILLER, S. et al. (2003): "Beyond Stippling - Methods for Distributing Objects on the Plane". Computer Graphics Forum 22, 3, September, pp. 515-522. http://dx.doi.org/10.1111/1467-8659.00699DALAL, K. et al. (2006): "A Spectral Approach to NPR Packing". In Proc. of NPAR, ACM, New York, pp. 71-78. http://dx.doi.org/10.1145/1124728.1124741BARLA, P. et al. (2006): "Interactive hatching and stippling by example". INRIA.SECORD A. et al. (2002): "Fast primitive distribution for illustration". In Thirteenth Eurographics Workshop on Rendering, pp. 215-226.SCHLECHTWEG S. et al. (2005): "Renderbots: Multi agent systems for direct image generation". Computer Graphics Forum 24, 283-290. http://dx.doi.org/10.1111/j.1467-8659.2005.00838.xMOULD D. (2007): "Stipple placement using distance in a weighted graph". In Proc. of Computational Aesthetics in Graphics, no. 3. p. unknown.KIM, S. et al. (2009): "Stippling By Example". In Proc. of NPAR, ACM, New York, pp. 41-50. http://dx.doi.org/10.1145/1572614.1572622ISENBERG, T. et al. (2005): "Breaking the Pixel Barrier". In Proc. of Cae, Eurographics Association, Aire-la-Ville, Switzerland, pp. 41-48.MACIEJEWSKI R. et al. (2008): "Measuring Stipple Aesthetics in Hand-Drawn and Computer-Generated Images", IEEE Computer Graphics and Applications, pp. 62-74. http://dx.doi.org/10.1109/MCG.2008.3

Image Sampling with Quasicrystals

We investigate the use of quasicrystals in image sampling. Quasicrystals produce space-filling, non-periodic point sets that are uniformly discrete and relatively dense, thereby ensuring the sample sites are evenly spread out throughout the sampled image. Their self-similar structure can be attractive for creating sampling patterns endowed with a decorative symmetry. We present a brief general overview of the algebraic theory of cut-and-project quasicrystals based on the geometry of the golden ratio. To assess the practical utility of quasicrystal sampling, we evaluate the visual effects of a variety of non-adaptive image sampling strategies on photorealistic image reconstruction and non-photorealistic image rendering used in multiresolution image representations. For computer visualization of point sets used in image sampling, we introduce a mosaic rendering technique