| 1. |
- Bergman, Lars, et al.
(författare)
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Unsupervised colour image segmentation applied to printing quality assessment
- 2005
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Ingår i: Image and Vision Computing. - Amsterdam : Elsevier. - 0262-8856 .- 1872-8138. ; 23:4, s. 417-425
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Tidskriftsartikel (refereegranskat)abstract
- We present an option for colour image segmentation applied to printing quality assessment in offset lithographic printing by measuring an average ink dot size in halftone pictures. The segmentation is accomplished in two stages through classification of image pixels. In the first stage, rough image segmentation is performed. The results of the first segmentation stage are then utilized to collect a balanced training data set for learning refined parameters of the decision rules. The developed software is successfully used in a printing shop to assess the ink dot size on paper and printing plates.
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| 2. |
- Bergman, Lars
(författare)
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Using Multicoloured Halftone Screens for Offset Print Quality Monitoring
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the newspaper printing industry, offset is the dominating printing method and the use of multicolour printing has increased rapidly in newspapers during the last decade. The offset printing process relies on the assumption that an uniform film of ink of right thickness is transferred onto the printing areas. The quality of reproduction of colour images in offset printing is dependent on a number of parameters in a chain of steps and in the end it is the amount and the distribution of ink deposited on the substrate that create the sensation and thus the perceived colours. We identify three control points in the offset printing process and present methods for assessing the printing process quality in two of these points:• Methods for determining if the printing plates carry the correct image• Methods for determining the amount of ink deposited onto the newsprintA new concept of colour impression is introduced as a measure of the amount of ink deposited on the newsprint. Two factors contribute to values of the colour impression, the halftone dot-size and ink density. Colour impression values are determined on gray-bars using a CCD-camera based system. Colour impression values can also be determined in an area containing an arbitrary combination of cyan magenta and yellow inks. The correct amount of ink is known either from a reference print or from prepress information. Thus, the deviation of the amount of ink can be determined that can be used as control value by a press operator or as input to a control system.How a closed loop controller can be designed based on the colour impression values is also shown.It is demonstrated that the methods developed can be used for off-line print quality monitoring and ink feed control, or preferably in an online system in a newspaper printing press.
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| 3. |
- Englund, Cristofer, et al.
(författare)
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A hybrid approach to outlier detection in the offset lithographic printing process
- 2005
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Ingår i: Engineering applications of artificial intelligence. - Amsterdam : Elsevier. - 0952-1976 .- 1873-6769. ; 18:6, s. 759-768
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Tidskriftsartikel (refereegranskat)abstract
- Artificial neural networks are used to model the offset printing process aiming to develop tools for on-line ink feed control. Inherent in the modelling data are outliers owing to sensor faults, measurement errors and impurity of materials used. It is fundamental to identify outliers in process data in order to avoid using these data points for updating the model. We present a hybrid, the process-model-network-based technique for outlier detection. The outliers can then be removed to improve the process model. Several diagnostic measures are aggregated via a neural network to categorize data points into the outlier and inlier classes. We demonstrate experimentally that a soft fuzzy expert can be configured to label data for training the categorization of neural network.
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| 4. |
- Englund, Cristofer, et al.
(författare)
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A SOM based model combination strategy
- 2005
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Ingår i: Advances in Neural Networks – ISNN 2005 Second International Symposium on Neural Networks, Chongqing, China, May 30 - June 1, 2005, Proceedings, Part I. - Berlin : Springer Berlin/Heidelberg. - 9783540259121 ; , s. 461-466
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Konferensbidrag (refereegranskat)abstract
- A SOM based model combination strategy, allowing to create adaptive – data dependent – committees, is proposed. Both, models included into a committee and aggregation weights are specific for each input data point analyzed. The possibility to detect outliers is one more characteristic feature of the strategy.
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| 5. |
- Stasiunas, Antanas, et al.
(författare)
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A multi-channel adaptive nonlinear filtering structure realizingsome properties of the hearing system
- 2005
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Ingår i: Computers in Biology and Medicine. - Amsterdam : Elsevier. - 0010-4825 .- 1879-0534. ; 35:6, s. 495-510
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Tidskriftsartikel (refereegranskat)abstract
- An adaptive nonlinear signal-filtering model of the cochlea is proposed based on the functional properties of the inner ear. The model consists of the cochlear filtering segments taking into account the longitudinal, transverse and radial pressure wave propagation. On the basis of an analytical description of different parts of the model and the results of computer modeling, the biological significance of the nonlinearity of signal transduction processes in the outer hair cells, their role in signal compression and adaptation, the efferent control over the characteristics of the filtering structures (frequency selectivity and sensitivity) are explained. © 2004 Elsevier Ltd. All rights reserved.
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| 6. |
- Stasiunas, Antanas, et al.
(författare)
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Compression, adaptation and efferent control in a revised outer hair cell functional model
- 2005
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Ingår i: Medical Engineering and Physics. - Amsterdam : Elsevier. - 1350-4533 .- 1873-4030. ; 27:9, s. 780-789
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Tidskriftsartikel (refereegranskat)abstract
- In the cochlea of the inner ear, outer hair cells (OHC) together with the local passive structures of the tectorial and basilar membranes comprise non-linear resonance circuits with the local and central (afferent–efferent) feedback. The characteristics of these circuits and their control possibilities depend on the mechanomotility of the OHC. The main element of our functional model of the OHC is the mechanomotility circuit with the general transfer characteristic y = k tanh(x − a). The parameter k of this characteristic reflects the axial stiffness of the OHC, and the parameter a working position of the hair bundle. The efferent synaptic signals act on the parameter k directly and on the parameter a indirectly through changes in the membrane potential. The dependences of the sensitivity and selectivity on changes in the parameters a and k are obtained by the computer simulation. Functioning of the model at low-level input signals is linear. Due to the non-linearity of the transfer characteristic of the mechanomotility circuit the high-level signals are compressed. For the adaptation and efferent control, however, the transfer characteristic with respect to the initial operating point should be asymmetrical (a > 0). The asymmetry relies on the deflection of the hair bundle from the axis of the OHC.
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| 7. |
- Verikas, Antanas, 1951-, et al.
(författare)
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Detecting and measuring rings in banknote images
- 2005
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Ingår i: Engineering applications of artificial intelligence. - Amsterdam : Elsevier. - 0952-1976 .- 1873-6769. ; 18:3, s. 363-371
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Tidskriftsartikel (refereegranskat)abstract
- Various intelligent systems show a rapidly growing potential use of visual information processing technologies. This paper presents an example of employing visual information processing technologies for detecting and measuring rings in banknote images. The size of the rings is one of parameters used to inspect the banknote printing quality. The approach developed consists of two phases. In the first phase, based on histogram processing and data clustering, image areas containing rings are localized and edges of the rings are detected. Then, in the second phase, applying the hard and possibilistic spherical shell clustering to the extracted edge pixels the ring centre and radii are estimated. The experimental investigations performed have shown that even highly occluded rings are robustly detected. Several prototypes of the system developed have been installed in two banknote printing shops in Europe. © 2004 Elsevier Ltd. All rights reserved.
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| 8. |
- Verikas, Antanas, et al.
(författare)
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Image analysis and fuzzy integration applied to print quality assessment
- 2005
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Ingår i: Cybernetics and systems. - London : Taylor & Francis. - 0196-9722 .- 1087-6553. ; 36:6, s. 549-564
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Tidskriftsartikel (refereegranskat)abstract
- We present an image analysis and fuzzy integration based option for the assessment of print quality in rotogravure printing. Values of several print distortion attributes are evaluated employing image analysis procedures and then are aggregated into an overall print quality measure using fuzzy integration. The experimental investigations performed have shown that the print quality evaluations provided by the measure correlate well with the print quality rankings obtained from the expert. The developed tools are successfully used in printing shops for routine print quality control.
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| 9. |
- Verikas, Antanas, et al.
(författare)
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Intelligent vocal cord image analysis for categorizing laryngeal diseases
- 2005
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Ingår i: Innovations in applied artificial intelligence. - Berlin, Heidelberg : Springer. - 9783540265511 ; , s. 69-78
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Konferensbidrag (refereegranskat)abstract
- Colour, shape, geometry, contrast, irregularity and roughness of the visual appearance of vocal cords are the main visual features used by a physician to diagnose laryngeal diseases. This type of examination is rather subjective and to a great extent depends on physician’s experience. A decision support system for automated analysis of vocal cord images, created exploiting numerous vocal cord images can be a valuable tool enabling increased reliability of the analysis, and decreased intra- and inter-observer variability. This paper is concerned with such a system for analysis of vocal cord images. Colour, texture, and geometrical features are used to extract relevant information. A committee of artificial neural networks is then employed for performing the categorization of vocal cord images into healthy, diffuse, and nodular classes. A correct classification rate of over 93% was obtained when testing the system on 785 vocal cord images.
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