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Dive into the research topics where Toni Kuparinen is active.

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Featured researches published by Toni Kuparinen.


IEEE Transactions on Pattern Analysis and Machine Intelligence | 2009

Optimal Reconstruction of Approximate Planar Surfaces Using Photometric Stereo

Toni Kuparinen; Ville Kyrki

Photometric stereo can be used to obtain a fast and noncontact surface reconstruction of Lambertian surfaces. Despite several published works concerning the uncertainties and optimal light configurations of photometric stereo, no solutions for optimal surface reconstruction from noisy real images have been proposed. In this paper, optimal surface reconstruction methods for approximate planar textured surfaces using photometric stereo are derived, given that the statistics of imaging errors are measurable. Simulated and real surfaces are experimentally studied, and the results validate that the proposed approaches improve the surface reconstruction especially for the high-frequency height variations.


scandinavian conference on image analysis | 2005

Fractal dimension analysis and statistical processing of paper surface images towards surface roughness measurement

Toni Kuparinen; Oleg Rodionov; Pekka Toivanen; Jarno Mielikainen; Vladimir Bochko; Ate Korkalainen; Juha Parviainen; Erik M. Vartiainen

In this paper we present a method for optical paper surface roughness measurement, which overcomes the disadvantages of the traditional methods. Airflow-based roughness measurement methods and profilometer require expensive special equipment, essential laboratory conditions, are contact-based and slow and unsuitable for on-line control purposes methods. We employed an optical microscope with a built-in CCD-camera to take images of paper surface. The obtained image is considered as a texture. We applied statistical brightness measures and fractal dimension analysis for texture analysis. We have found a strong correlation between the roughness and a fractal dimension. Our method is non-contact–based, fast and is suitable for on-line control measurements in the paper industry.


discrete geometry for computer imagery | 2006

Distance transforms on anisotropic surfaces for surface roughness measurement

Leena Ikonen; Toni Kuparinen; Eduardo Villanueva; Pekka J. Toivanen

The Distance Transform on Curved Space (DTOCS) calculates distances along a gray-level height map surface In this article, the DTOCS is generalized for surfaces represented as real altitude data in an anisotropic grid The distance transform combined with a nearest neighbor transform produces a roughness map showing the average roughness of image regions in addition to one roughness value for the whole surface The method has been tested on profilometer data measured on samples of different paper grades The correlation between the new method and the arithmetic mean deviation of the roughness surface, Sa, for small wavelengths was strong for all tested paper sample sets, indicating that the DTOCS measures small scale surface roughness.


international conference on image processing | 2007

On Surface Topography Reconstruction from Gradient Fields

Toni Kuparinen; Ville Kyrki; Jarno Mielikainen; Pekka Toivanen

In this paper, we propose and study surface reconstruction techniques for surfaces with high frequency height variation, which are common for example, in paper and textile manufacturing. Traditionally, photometric stereo methods have been developed and evaluated on objects with additive Gaussian noise. The minimization based methods may perform well on large objects, but they smooth the inherent high frequency variation of machined surfaces in the reconstruction. We extend a Fourier integration method with Wiener filter to reconstruct surfaces from two gradient fields. The experimental results validate that the proposed method performs well on surfaces with high frequency height variation.


scandinavian conference on image analysis | 2003

Enhanced model for chromaticity differences

Toni Kuparinen; Arto Kaarna; Pekka J. Toivanen

We have developed a model to calculate chromaticity differences from surfaces defined from the MacAdam ellipses in CIE 1931 (x,y)-chromaticity diagram. The idea is to transform the MacAdam ellipses to circles on planes and to connect these planes to each other as two surfaces through interpolation. The distances along the surfaces are calculated by a method based on the Weighted Distance Transform On Curved Space (WDTOCS). The chromaticity difference is calculated by combining the distances on the basis of the ellipse parametrization. The surface model corrects the planar values in chromaticity difference calculation. Our method can be applied to any set of planar ellipses.


Journal of Machine Vision and Applications | 2007

Paper Surface Topography Using Three-light Photometric Stereo

Toni Kuparinen; Ville Kyrki; Jarno Mielikainen; Pekka Toivanen


Archive | 2013

A method for monitoring accumulation of impurities on a rubber blanket

Toni Kuparinen; Lauri Eino William Faloon; Juha Parviainen; Petri Väätäjä; Peter Petermann


international conference on computer vision theory and applications | 2008

MEASUREMENT NOISE IN PHOTOMETRIC STEREO BASED SURFACE RECONSTRUCTION

Toni Kuparinen; Ville Kyrki; Pekka Toivanen


Journal of Imaging Science and Technology | 2005

Computational surface models for chromaticity differences

Toni Kuparinen; Arto Kaarna; Pekka Toivanen


international conference on computer graphics, imaging and visualisation | 2004

Computational Model for Chromaticity Differences.

Toni Kuparinen; Arto Kaarna; Pekka Toivanen

Collaboration


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Pekka Toivanen

University of Eastern Finland

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Arto Kaarna

Lappeenranta University of Technology

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Jarno Mielikainen

University of Wisconsin-Madison

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Juha Parviainen

Lappeenranta University of Technology

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Pekka J. Toivanen

Lappeenranta University of Technology

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Ate Korkalainen

Lappeenranta University of Technology

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Eduardo Villanueva

Lappeenranta University of Technology

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Erik M. Vartiainen

Lappeenranta University of Technology

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Leena Ikonen

Lappeenranta University of Technology

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