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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Unique-Bit-Pattern-Based Indexing Strategy for Image Rotation and Reflection in Image Databases

Yeh, Wei-horng 16 June 2008 (has links)
A symbolic image database system is a system in which a large amount of image data and their related information are represented by both symbolic images and physical images. Spatial relationships are important issues for similarity-based retrieval in many image database applications. How to perceive spatial relationships among the components in a symbolic image is an important criterion to find a match between the symbolic image of the scene object and the one being store as a modal in the symbolic image database. With the popularity of digital cameras and the related image processing software, a sequence of images are often rotated or flipped. That is, those images are transformed in the rotation orientation or the reflection direction. A robust spatial similarity framework should be able to recognize image variants such as translation, scaling, rotation, and arbitrary variants. Current retrieval by spatial similarity algorithms can be classified into symbolic projection methods, geometric methods, and graph-matching methods. Symbolic projection could preserve the useful spatial information of objects, such as width, height, and location. However, many iconic indexing strategies based on symbolic projection are sensitive to rotation or reflection. Therefore, these strategies may miss the qualified images, when the query is issued in the orientation different from the orientation of the database images. To solve this problem, researchers derived the rule of the change of spatial relationships in image transformation, and proposed a function to map the spatial relationship to its related transformed one. However, this mapping consists of several conditional statements, which is time-consuming. Thus, in this dissertation, first, we classify the mapping into three cases and carefully assign a 16-bit unique bit pattern to each spatial relationship. Based on the assignment, we can easily do the mapping through our proposed bit operation, intra-exchange, which is a CPU operation and needs only the complexity of O(1). Moreover, we propose an efficient iconic index strategy, called Unique Bit Pattern matrix strategy (UBP matrix strategy) to record the spatial information. In this way, when doing similarity retrieval, we do not need to reconstruct the original image from the UBP matrix in order to obtain the indexes of the rotated and flipped image. Conversely, we can directly derive the index of the rotated or flipped image from the index of the original one through bit operations and the matrix manipulation. Thus, our proposed strategy can do similarity retrieval without missing the qualified database images. In our performance study, first, we analyze the time complexity of the similarity retrieval process of our proposed strategy. Then, the efficiency of our proposed strategy according to the simulation results is presented. We show that our strategy outperforms those mapping strategies based on different number of objects in an image. According to the different number of objects in an image, the percentage of improvement is between 13.64% and 53.23%.
2

Towards automatic smartphone analysis for point-of-care microarray assays

Erkers, Julia January 2016 (has links)
Poverty and long distances are two reasons why some people in the third world countries hasdifficulties seeking medical help. A solution to the long distances could be if the medical carewas more mobile and diagnostically tests could be performed on site in villages. A new pointof-care test based on a small blood shows promising results both in run time and mobility.However, the method still needs more advanced equipment for analysis of the resultingmicroarray. This study has investigated the potential to perform the analysis within asmartphone application, performing all steps from image capturing to a diagnostic result. Theproject was approach in two steps, starting with implementation and selection of imageanalysis methods and finishing with implementing those results into an Android application.A final application was not developed, but the results gained from this project indicates that asmartphone processing power is enough to perform heavy image analysis within a sufficientamount of time. It also imply that the resolution in the evaluated images taken with a Nexus 6together with an external macro lens most likely is enough for the whole analysis, but furtherwork must be done to ensure it.
3

Estimation and Correction of the Distortion in Forensic Image due to Rotation of the Photo Camera

Bavikadi, Sathwika, Botta, Venkata Bharath January 2018 (has links)
Images, in contrast to text, represent an effective and natural communication media for humans, due to their immediacy and the easy way to understand the image content. Shape recognition and pattern recognition are one of the most important tasks in the image processing. Crime scene photos should always be in focus and there should always be a ruler be present, this will allow the investigators the ability to resize the image to accurately reconstruct the scene. Therefore, the camera must be on a grounded platform such as tripod. Due to the rotation of the camera around the camera center there exist the distortion in the image which must be minimized. The distorted image should be corrected using transformation method. Deze taak is nogal uitdagend en essentieel omdat elke verandering in de afbeeldingen kan misidentificeren een object voor onderzoekers. Forensic image processing can help the analyst extract information from low quality, noisy image or geometrically distorted. Obviously, the desired information must be present in the image although it may not be apparent or visible. Considering challenges in complex forensic investigation, we understand the importance and sensitivity of data in a forensic images.The HT is an effective technique for detecting and finding the images within noise. It is a typical method to detect or segment geometry objects from images. Specifically, the straight-line detection case has been ingeniously exploited in several applications. The main advantage of the HT technique is that it is tolerant of gaps in feature boundary descriptions and is relatively unaffected by image noise. The HT and its extensions constitute a popular and robust method for extracting analytic curves. HT   attracted a lot of research efforts over the decades. The main motivations behind such interest are the noise immunity, the ability to deal with occlusion, and the expandability of the transform. Many variations of it have evolved. They cover a whole spectrum of shape detection from lines to irregular shapes. This master thesis presents a contribution in the field of forensic image processing. Two different approaches, Hough Line Transformation (HLT), Hough Circular Transformation (HCT) are followed to address this problem. Fout estimatie en validatie is gedaan met de hulp van root mean square method. De prestatie van beide methoden is geëvalueerd door ze te vergelijken. We present our solution as an application to the MATLAB environment, specifically designed to be used as a forensic tool for forensic images.

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