Kari P. Saarinen

Color image segmentation by a watershed algorithm and region adjacency graph processing

A new method for gray-scale, color and multispectral image segmentation is proposed. The method is based on a morphological split-and-merge fast watershed algorithm and region adjacency graph processing. It features partly iterative processing with relatively low computational load. Two system alternatives are presented and their application to color image segmentation is discussed. First computer simulations show correctness of operation and encourage for further research.<<ETX>>

Digital adaptive robust algorithms for radar image filtering

Novel adaptive robust filtering algorithms applicable to radar image processing are proposed. They take into consideration the peculiarities of radar images and possess a good combination of properties: effective speckle suppression, impulsive noise removal, edge and detail preservation and low computational complexity. The advantages of these digital algorithms are demonstrated by simulated data and images obtained by airborne side-look non SAR radar.

Algorithms of image nonlinear adaptive filtering using fragment recognition by expert system

The expedience of use of expert system and fuzzy logic based decisions to image recognition and filtering is discussed. One possible approach including the calculation of several local parameters for every image pixel scanning window position combined with expert system preliminary training and decision undertaking for image recognition and adaptive filtering is proposed. The efficiency and the peculiarities of considered procedure are analyzed and demonstrated for simulated data.

Comparison of decimation and interpolation methods in case of multiple repeated RGB-YCbCr colour image format conversions

The performance of different interpolators and decimators for RGB-YCbCr colour image format conversions was studied. The main attention was given for performance in multiple repeated conversions. New interpolators designed by the author were also evaluated. Visual quality differences were small after a single conversion but became considerably larger in repeated conversions.<<ETX>>

Adaptive-vector LQ filter for color image processing

Robust adaptive vector filtering algorithms applicable to color and multichannel image processing are proposed. They are based on the use of Q-parameter that is a vector analog of quasirange. Considered algorithms have a good combination of properties: effective noise reduction, ability to remove spikes, edge and detail preservation, and low computational complexity. Their characteristics are evaluated quantitatively and compared to non-adaptive counterparts. Advantages of proposed algorithms are also demonstrated by simulated image processing results.

Adaptive nonlinear vector filtering of multichannel radar images

Here we consider the possibility of applying vector median filtering for joint processing of multichannel radar images. The goal is to correct distortions due errors in superimposing of channels. The proposed approach is a two-stage one. It takes into account the difference between statistical characteristics of images formed by side-look aperture radar (SLAR) and synthetic aperture radar (SAR) and uses the correlation properties of the signal processed by vector filter. Image enhancement is achieved as many false edges are eliminated and contrast of true edges is increased. Filter properties are analyzed both with simulated test images and real radar data.

Hard-switching adaptive filter for speckle image processing

The ways to improve the computational efficiency of the Frost filter and make it robust in respect to spikes are considered. A hard-switching adaptive procedure is proposed and the aspects of proper selection of linear filter parameters and threshold values are discussed. Then the idea of subsequent application of FTR- median hybrid filter is put forward. Quantitative and visual simulation results are presented for different p.d.f.s of multiplicative noise to compare the properties and to demonstrate the advantages of proposed modifications. Real synthetic aperture radar and artificial image processing results are demonstrated.

Adaptive α-trimmed filters for speckle image processing

A new class of adaptive (alpha) -trimmed filters well suited for processing of images corrupted with non-symmetrical p.d.f. speckle and impulsive noise is proposed. It is shown that in certain cases one can provide a better speckle reduction and impulse removal by non-symmetrical trimming. Appropriate edge/detail preservation is ensured due to adaptation of the scanning window size or application of detail preserving Lpq-filter. Selection of adaptation parameter is discussed as well. The efficiency and properties of the proposed filters are demonstrated and quantitatively evaluated for test and real data.

Nonlinear algorithms of isogram extraction from topographic maps

A method for isogram extraction from topographic maps is proposed and analyzed. Main part of the extraction is done using automatic software based on nonlinear algorithms. Possibly needed final corrections are done in an interactive mode. Iterative procedures are used both to provide reliability and to minimize the number of operations performed by the user in the interactive mode. Illustrations are presented to clarify the operations, goals and obtained results. Also, techniques for relief recovery are proposed and their accuracy is studied.

A visual simulator for full-colour thin-film electroluminescence displays

Abstract A software-based simulation system for full-colour thin-film electroluminescence (TFEL) displays is presented. The developed system provides tools for simulating the visual appearance of full-colour TFEL displays on a high-resolution shadow mask colour cathode-ray tube. The visual appearance of TFEL colour display configurations with different phosphors, colour cell geometric layouts, resolutions and frame rates can be simulated. It is possible to examine the spatial and temporal artifacts that can occur in a specific colour TFEL display configuration with text, graphics and video. The system facilitates visual performance optimization in full-colour TFEL display design. Important simulation parameters and central problems are discussed, and references to earlier work on the area are given.