3D live-wire: Semi-automatic segmentation of volume images in a haptic environment
Student: Filip Malmberg
Supervisor: Ingela Nyström
Subject supervisor: Ewert Bengtsson
Publisher: CBA Master Thesis 82
Abstract:
In computerized image analysis, most applications require the images to
be segmented into
objects of interest at some stage in the process. Segmentation is a difficult task, and sometimes it is not possible to achieve a good segmentation using automatic methods alone. In such cases, it might be necessary to utilize interactive, semi-automatic methods.
As volume images become increasingly common there is a need to extend existing image analysis tools to also handle 3D images. Segmenting volume images with interactive methods is difficult, mainly because efficient interaction with a 3D image is much harder to achieve than interaction with 2D images. We have used a system that uses stereo graphics and haptic feedback to facilitate efficient 3D interaction.
We propose a new method, based on the 2D live-wire method, for segmenting volume images. Our method consists of two parts: an interface for drawing 3D live-wire curves onto a surface in a volume image, and an algorithm for connecting two such curves to create a surface. We also discuss some problems encountered with our method, and possible ways of solving them.
- Non-contact quality measurements of open die forging - development of a laser triangulation system
Student: Björn Nilsson
Supervisor: Jan Wipenmyr, IMEGO AB, Göteborg
Subject supervisor: Gunilla Borgefors
Partner: IMEGO AB, Göteborg
Publisher: CBA Master Thesis 83
UU School of Engineering, UPTEC F06 002
Abstract: A demo system for non-contact measurements of dimensions on open die forging has been developed by IMEGO AB, Göteborg and SINTEF, Olso, on comission of the steel industry companies: Scana Steel Björneborg AB, Uddeholm Tooling AB and Sandvik Materials Technology AB.
The concept for the demo system is based on the principle of triangulation for measuring and composing cross-sections of wrought-iron goods. When used for reference measurements the system has proved to be accurate with millimetre precision.
In this thesis, software for collecting and processing of measurement data have been proposed and integrated into two graphical user interfaces. One program was developed for presentation purposes and one for management of measurements.
- An optical character recognition method for an automatic number plate recognition application applied to Swedish number plates
Student: Johan Östrand
Supervisor: Pär Dahlund, KFG AB, Sandviken
Subject supervisor: Patrick Karlsson
Partner: KFG AB, Sandviken
Publisher: CBA Master Thesis No. 84
UU School of Engineering, UPTEC F06 026
Abstract: The use of automatic number plate recognition (ANPR) is crucial in many traffic surveillance applications. One step in an ANPR application is the optical character recognition (OCR) where a computer interprets images of characters as text. This master thesis presents an OCR method for an ANPR application on Swedish number plates. In this application the assumption is made that the position of the number plate in the image is known. Character recognition was achieved by applying template matching on the greylevel of the original image. The method was implemented and tested on 217 images from nine datasets with different characteristics. The percentage of correctly read number plates, assuming a standard number plate context, i.e., three letters and then three digits, was 48%. When not assuming a standard number plate context, i.e., including the letters Å, Ä and Ö and allowing 2 to 7 characters, the accuracy was 24%. Some characters were found to be difficult for the method to differentiate between when using a standard number plate context, e.g., 6, 5 and 8, D and O, and F and E. When not assuming standard number plate context also the character sets A and Ä and, D, O and 0 were hard for the method to separate.
Automatic camera-surveillance of the dried river-bed for increased public safety
Student: Jesper Renck
Supervisor: Daniel Nordgren, Vattenfall Utveckling AB
Subject supervisor: Gunilla Borgefors
Partner: Vattenfall Utveckling, Älvkarleby
Publisher: CBA Master Thesis No. 85
UU School of Engineering, IT 06 016
Comment: In Swedish
Abstract: This thesis was partly aimed at surveying possible applications for image analysis within hydropower and partly to designing and developing a prototype for one application. The survey shows that, for most of the propositions, the need is too small compared to the possible failure rate of the advanced technical equipment. From the eleven evaluated proposals one of them, automatic camera-surveillance of the dried river-bed for increased public safety, was selected for further work. The further work included a preliminary study which led to a specification for the system. This study found that the risks where not very high but that surveillance could be motivated for 23 of Vattenfall's 53 hydropower plants. After this a prototype was developed, based on segmentation of movement in the image-sequence, analysis of the movements based on shape, size and speed were used to separate movement of interesting objects from movement in background of the scene. The evaluation of the system shows the performance for a few representative test-cases. The result is well acceptable under good to medium light conditions and normal visibility. The algorithm detect and track the interesting object both moving and when standing still. False alarms appear but are few and mainly appear in connection with the interesting object.
- Image segmentation for Alcro colouring program/Becker's Painter
Student: Carl Johan Otterheim
Supervisor: Caroline Staedler, MRM Worldwide, Stockholm
Subject supervisor: Gunilla Borgefors
Partner: MRM Worldwide, Stockholm
Publisher: CBA Master Thesis No. 86
UU School of Engineering, UPTEC IT 06 029
Comment: In Swedish
Abstract: Image analysis is a topic of ever growing popularity around the globe. Nowadays it affects not only corporations using it within an economic interest, but also the average user who for example uses a digital camera. Object segmentation is the process of finding, outlining and extracting objects in an arbitrary digital image. This process can be done with a variety of tools, but most of the time these are too complicated for the inexperienced user to handle. The object of this master thesis work is to identify and implement a solution for segmenting an image and to be able to use the result with an already existing application made by MRM Worldwide. The application is made to let users repaint areas of a house on a digital image. The solution identified requires a very small amount of interaction from the user to make it as easy as possible. The method is a combination of different techniques based on colour space projections and watershed segmentation combined with seeding information given by the user.
- Estimation of local fibre orientation in paper using steerable filters
Student: Per Uddholm
Supervisor: Fredrik Rosén, STFI-Packforsk AB, Stockholm
Subject supervisor: Gunilla Borgefors
Partner: STFI-Packforsk AB, Stockholm
Publisher: CBA Master Thesis No. 87
Abstract: Steerable filters are evaluated as tools for determining the fibre orientation in paper. Filters due to Freeman and Adelson and to Jacob and Unser are presented and compared. Both are compared with a simple gradient filter. Several model fibre orientation probability distributions are compared. The effects of the filter parameters, e.g., filter order and filter kernel width are studied. The filters' noise properties and their ability to reproduce known (synthetic) fibre orientations are also investigated. In addition, the effect of the use of a rectilinear co-ordinate system, which introduces preferred directions, and the subarea size are considered. Steerable filters, as well as the gradient filter, seem to reproduce the fibre orientation angle well. Estimating the fibre orientation anisotropy is considerably more difficult, and requires careful calibration. Jacob and Unser filters are observed to have better noise properties than the gradient filter, while those of the Freeman and Adelson filter are inferior. Steerable filters, however, are much slower than the gradient filter. Some modifications to Jacob and Unser's original work is also suggested.
- Automated abdominal tissue segmentation of multicontrast magnetic resonance images
Student: Olena Tankyevych
Supervisor: Joel Kullberg, Dept. of Oncology, Radiology and Clinical Immunology; Ingela Nyström
Subject supervisor: Ewert Bengtsson
Partner: Dept. of Oncology, Radiology and Clinical Immunology, UU
Publisher: CBA Master Thesis No. 88
Abstract:
Abdominal fat tissue and liver volume are interesting in studies of many diseases, e.g. cardiovascular, diabetes, obesity. Although there have been only few works which developed automated or semi-automated abdominal tissue segmentation.
Magnetic Resonance Imaging (MRI) is a medical imaging technology that provides rich information about soft body tissues. Properties of MRI can give complementary contrast information from the body tissues.
Fuzzy c-means (FCM) clustering method assigns pixels of the image to different clusters according to their distance to the cluster centres in a feature space. But the original FCM does not utilize any spatial information for the segmentation, which is crucial in many cases, and especially in medical images.
In this master thesis we have acquired different MRI sequences and combined them in order to form an intensity feature space for an unsupervised spatial and original FCM classification.
- Image analysis of current collectors
Student: Jonas Jämtberg
Supervisor: Kjell Wallin, Sensys Traffic
Subject supervisor: Ewert Bengtsson
Partner: Sensys Traffic, Uppsala
Publisher: CBA Master Thesis No. 89
UU School of Engineering, UPTEC IT06 008
Comment: In Swedish
Abstract: The goal of this project was to develop a technology trial for automatic identification of current collectors on locomotives. The project was carried out at Sensys Traffic AB in Uppsala and Banverket. Sensys has developed KIKA on commission from Banverket. KIKA is a system that automatically detects damages using photographs of current collectors and reports them to the nearest control center. This project may in the future add automatic identification to KIKA's functionality. Identification is done by comparing the photographs of passing current collectors to a library of CAD-models of the same. In order to get the CAD-model in proper perspective the system is required to have good knowledge of the surrounding environment. The system is able to lock on to a current collector and calculate a fidelity value in about 40 seconds.
- Skanner som detektionsinstrument
Student: Mikael Lönnberg
Supervisor: Dept. of Physical & Analytical Chemistry, UU
Subject supervisor: Ewert Bengtsson
Partner: Surface Biotechnology, Dept. of Physical & Analytical Chemistry, UU
Publisher: CBA Master Thesis No. 90
Comment: In Swedish
Abstract: En bildskanner kan kvantifiers mängden svärta på en mätyta och skapa en bild med ett numeriskt värde för varje pixel. Detta kan användas för att mäta svärtningsstyrkan i detektionszonen på tunna membranbitar som bearbetas i immunokromatografiska tester. Ett bra detektionsinstrument ska bestämma svärtingsstyrkan med god mätprecision och ha tillräcklig känslighet för att urskilja en knappt synlig svärtning i detektionszonen.
I detta examensarbete identifieras skanneregenskaper och mätförhållanden som påverkar resultatet av mätningarna. Prestanda för tre olika skannrar i varierande prisklass har jämförts och optimala mätbetingelser har utarbetats. Skannrar som används med noga uppstyrd mätprocedur fungerar utmärkt som detektionsinstrument. Samtliga skannrar uppvisar en mätprecision på mindre än en procent i variationskoefficient vid mätning av svagt synliga ljusgrå band.
- The impact of NEQ on detectability of microcalcifications in mammography
Student: Åsa Berglund
Supervisor: Mats Danielsson, Sectra Imtec AB
Subject supervisor: Carolina Wählby
Partner: Sectra Imtec AB, Kista
Publisher: CBA Master Thesis No. 91
UU School of Engineering, UPTEC F06 063
Abstract:
In mammography it is very important to be able to identify so called microcalcifications in the breast, since they may be an early sign of cancer. This work investigates how the visibility of microcalcifications is affected when certain parameters in the mammography system are changed.
An existing model of the Sectra MDM D40 system was further developed and verified against experimental measurements. Software was developed for simulating mammography images with microcalcifications, based on the system model. Different system settings were investigated to obtain the best system parameters for detection of 100 micrometer microcalcifications.
To evaluate the visibility of microcalcifications a human observer study was performed, and a mathematical model observer was implemented and compared to human performance.
The studies showed that increasing the slit width resulted in better visibility of the microcalcifications, if maximum dose was used for all slit widths. However, the clinical benefit has to be weighed against the dangers with increased dose to the patient. A slit width of around 100 micrometer is proposed as the best trade-off between image quality and patient dose.
The use of a micro focal spot results in somewhat better visibility, if the same dose as for the normal focal spot is achieved. But the time needed for the image acquisition then becomes so long that this approach is not recommended. Using a system with normal focal spot and narrower slit width results in the same visibility without increasing the scan time as much.
- Contour extraction and modelling of horses using background subtraction and active shape models
Student: Petter Holmberg
Supervisor: Joakim Lindblad
Subject supervisor: Gunilla Borgefors
Publisher: CBA Master Thesis No. 92
Abstract:
Anatomical information about horses can be extracted from still images, using markers placed on the horse and manual inspection of marker positions. However, it is a time-consuming process both to place markers and to extract coordinate data from them manually. It is therefore of interest to study if computerized image analysis can be used to extract the contour of horses from images taken without too strict limitations on the setup, and if contour features can be extracted and used to obtain reliable anatomical measurements, thereby reducing the amount of manual work needed to collect the data.
In this master's thesis, we propose a segmentation method based on background subtraction for finding the contour of horses (and other objects) with consideration to noise and shadows, and use active shape models to locate and identify contour features. The methods are implemented as a MATLAB program. We also discuss problems and limitations of the methods, as well as possible future extensions of the project.
- Improved segmentation and classification of seeds
Student: Yao Wang
Supervisor: Jan Luup, Maxx Automation AB
Subject supervisor: Ewert Bengtsson
Partner: Maxx Automation AB, Uppsala
Publisher: CBA Master Thesis No. 93
Abstract: Improvements on segmentation and classification of seeds were done for the automatic seed analyzer Seedscanner2003 in both hardware and software aspects. The segmentation improvements were achieved by using a new plate as background which enables segmentation of seeds with various color ranges. Classification was based on 26 morphological, color, edge and texture features using Mahalanobis distance method. Features importance is analyzed. Cracked barley detection was accomplished using color and edge analysis. Wheat varieties discrimination issue was not successfully solved with several tested methods presented and discussed. The final experiments illustrate that a satsifactory high classification accuracy is achieved among all seed species included in the machine. Classification performance between wheat and triticale was greatly enhanced.
