Weszka, J.

Physica status solidiVolume 61, Number 1, January 1( )

1 edition published in 2022 in English and held by 21 WorldCat member libraries worldwide

Threshold evaluation techniques by Joan Shirley Weszka( Book )

6 editions published in 1977 in English and Undetermined and held by 7 WorldCat member libraries worldwide

Threshold selection techniques have been used as a basic tool in image segmentation, but little work has been done on the problem of evaluating a threshold of an image. This paper addresses the problem of threshold evaluation and proposes two methods for measuring the goodness of a thresholded image, one based on a busyness criterion and the other based on a discrepancy or error criterion. These evaluation techniques are applied to both synthetic and real images and are shown to be useful in facilitating threshold selection. In fact, both methods usually result in similar or identical thresholds which yield good segmentations of the images. (Author)

Histogram modification for threshold selection by J Weszka( Book )

5 editions published in 1977 in English and held by 6 WorldCat member libraries worldwide

A standard approach to threshold selection for image segmentation is based on locating valleys in the image's gray level histogram. Several methods have been proposed that produce a transformed histogram in which the valley is deeper, or is converted into a peak, and is thus easier to detect. The transformed histograms used in these methods can all be obtained by creating (gray level, edge value) scatter plots, and computing various weighted projections of these plots on the gray level axis. Using this unified approach makes it easier to understand how the methods work and to predict when a particular method is likely to be effective. The methods are applied to a set of examples involving both real and synthetic images, and the characteristics of the resulting transformed histograms are discussed. (Author)

Physica status solidiVolume 133, Number 1, January 1( )

1 edition published in 1986 in English and held by 4 WorldCat member libraries worldwide

Thin Films of Aromatic Polyazomethines by Weszka J( )

1 edition published in 2010 in English and held by 3 WorldCat member libraries worldwide

Polyazomethine thin films can be prepared by chemical vapor deposition and thermal vacuum evaporation. It has been shown that structure, morphology and optical spectra of polyazomethine thin films are dependent on technological conditions they were deposited. Their optical spectra reveal features resembling optical spectra of polyparaphenylene vinylene. It is expected that low transport rate of monomers to the substrate independently of the setup used are favorable for small growth rates and optical spectra reveal features being resultant of distribution length of conjugated fragment in various chains within the whole thin film volume. High flow rates of transport agent have appeared favorable for excitonic feature of Wannier-Mott type to overlap low energy side of the absorption band due to transitions linking delocalized states. This could be attributed to geminate pairs or to stronger overlap of molecular orbitals of more planarized chains to form larger ordered areas where conjugation is not limited to conjugated fragments of individual chains but to some areas of thin film comprising several chains. On the other hand, one can see that polyazomethine spectra can be modified by using various more or less complex diamines aromatic with therephthal aldehyde. These spectra resemble those of PPV but one may expect that rather low intensity of low energy band due to interband transitions connecting delovcalized states due to lower degree of planarity, which to some extent recompense by relatively large -electron system within such polymer monomer. Then, doping PPI thin films have exhibited features characteristic of PPV, which support similar polaron mechanisms driving doping PPI and PPV. This has appeared to go within this picture whether PPI thin films were iodine doped by diffusion in the iodine vapor or with the use of FeCl3 in the process of thin film deposition. Additionally, it has been proved that incorporation of oxygen atoms into PPI chain, which result in dividing its conjugated fragments into quite short ones bringing about an increase in absorption gap but other features resemble those of PPI. The scope of this chapter has not allowed for electronic structure and atom dynamics of polyazomethine thin films to be discussed in details

Picture processing by Azriel Rosenfeld( Book )

3 editions published in 1975 in English and Undetermined and held by 2 WorldCat member libraries worldwide

This paper reviews the fundamentals of automatic picture processing and scene analysis. It discusses computer-based methods of segmenting pictures into meaningful parts; determining properties of the parts and relationships among the parts; and using this information to construct descriptions of the pictures. The material is organized by principal areas of application, including document reading, high-energy physics, cytology, radiology, and remote sensing of the environment

Final report on workshop on control structures and knowledge representation for image and speech understanding, April 3-4, 1979, Center for Adult Education, University of Maryland, College Park, MD. 20742. Principal investigators: Raj Reddy, Carnegie-Mellon University. Azriel Rosenfeld, University of Maryland. Report prepared by Joan Weszka, IBM Corporation by Carnegie Mellon University( Book )

1 edition published in 1979 in English and held by 1 WorldCat member library worldwide