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Öğe Anisotropic diffusion filter without conductivity parameters(2012) Demirci, Recep; Güvenç, Uğur; Tanyeri, UfukTwo novel automatic anisotropic diffusion filters without conduction parameters were proposed in this paper. In the proposed first method, initially, the gradient of the noisy image to be filtered was calculated by Sobel operator and then the center of gravity of gradient image was used as diffusivity parameter, K and edge threshold. It was observed that the center of gravity of gradient image changed with noise. In the second approach, the complement of gradient image was directly employed as heat conductivity parameter in image filter. Consequently, the user dependency was avoided. The proposed image filter was tested with well-known test images. © 2012 Dunarea de Jos University.Öğe Design, Implementation and Test of a Novel Cylindrical Permanent Magnet DC Linear Motor(Mdpi, 2023) Demirkol, Ziya; Hasirci, Ugur; Demirci, RecepElectric motors that convert electrical energy into motion are one of the basic components of automation systems. In these systems, either linear or circular motion is needed. Linear motion can be obtained either from motors that generate circular motion with the help of ancillary equipment or directly by the means of a linear motor. Obtaining linear motion from motors that produce rotary motion leads to additional costs and reduced efficiency. Linear motors, on the other hand, eliminate the need for conversion mechanisms. Despite this advantage, linear motors have some disadvantages, such as length limitation and low force/current ratio. In this study, a novel Cylindrical Direct Current Linear Motor (CDCLM) with high force/current ratio and no length limitation (long stroke) has been developed. Analyses of the developed motor has been performed with an analytical method. In addition, detailed numerical analyses have been carried out in an Ansys-Maxwell environment. A prototype of the designed DC linear motor has been implemented in a laboratory environment and experimental analyses have been carried out. The results of analytical, numerical and experimental analyses have been compared.Öğe Fuzzy adaptive anisotropic filter for medical images(Wiley, 2010) Demirci, RecepAn adaptive anisotropic diffusion filter for images is proposed in this paper. First, the gradient of an image was calculated by a novel fuzzy-rule-based gradient operator. Accordingly, the centre of gravity of a histogram of the gradient image was estimated and it was assigned as an edge threshold. In conventional anisotropic filters, the conduction coefficients have to be selected by an operator. However, in this study, the centre of gravity of the histogram was assigned as the conduction coefficient of the anisotropic filter. Consequently, an adaptive anisotropic image filter which automatically sets its conduction coefficient without user intervention was developed. The image filter achieved was tested with various medical images.Öğe Fuzzy diffusion filter with extended neighborhood(Pergamon-Elsevier Science Ltd, 2013) Elmas, Çetin; Demirci, Recep; Güvenç, UğurAnisotropic diffusion filters, which are motivated from heat diffusion between mediums, have become a widely used technique in the field of image processing. In the initial proposals of anisotropic diffusion filters, 4-neighborhood values with diffusivity functions are computed independently for each spatial location because of numerical approximation. However, anisotropic diffusion filters could not be used in real-time image and video processing applications because they need diffusivity parameters, which must be specified by users in every sampling period. In this study, a fuzzy adaptive diffusion filter using extended neighborhood without diffusivity functions has been developed. The fuzzy adaptive diffusion filter does not require any parameter chosen by user and therefore they could be employed in real-time applications. In the fuzzy adaptive diffusion filter, a similarity transformation by means of relation matrix and fuzzy logic is carried out. Accordingly, the similarity image, output of transformation, is directly used as a heat diffusion coefficient in the diffusion filter. Results show that the fuzzy adaptive diffusion filter is very efficient for removing noise in image while preserving edges. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Light refraction based medical image segmentation(Academic Journals, 2010) Güvenç, Uğur; Demirci, Recep; Karagül, TubaImage segmentation is the most important and first step in pattern recognition and image analysis. In this paper, an automatic segmentation algorithm based on light refraction was proposed for medical images. In the proposed algorithm, similarity percents of the pixels were calculated by using the amount of shift while occurred light through a transparent sheet and re-enters the same environment. The proposed algorithm is similar to region growing algorithm where the seed points are automatically selected and grown and does not require any prior knowledge of the number of regions existing in the image. So, it decreases the computational load required for the other image segmentation methods. The proposed algorithm is demonstrated by application to real medical images. Results have showed that proposed algorithm extract all segments effectively.Öğe Measurement of epidermal thickness in a patient with psoriasis by computer-supported image analysis(Associacao Brasileira de Divulgacao Cientifica, 2004) Alper, Murat; Kavak, Ayşe; Parlak, Ali Haydar; Demirci, Recep; Belenli, İbrahim; Yeşildal, NurayThe aim of the present study was to measure full epidermal thickness, stratum corneum thickness, rete length, dermal papilla widening and suprapapillary epidermal thickness in psoriasis patients using a light microscope and computer-supported image analysis. The data obtained were analyzed in terms of patient age, type of psoriasis, total body surface area involvement, scalp and nail involvement, duration of psoriasis, and family history of the disease. The study was conducted on 64 patients and 57 controls whose skin biopsies were examined by light microscopy. The acquired microscopic images were transferred to a computer and measurements were made using image analysis. The skin biopsies, taken from different body areas, were examined for different parameters such as epidermal, corneal and suprapapillary epidermal thickness. The most prominent increase in thickness was detected in the palmar region. Corneal thickness was more pronounced in patients with scalp involvement than in patients without scalp involvement (t = -2.651, P = 0.008). The most prominent increase in rete length was observed in the knees (median: 491 ?m, t = 10.117, P = 0.000). The difference in rete length between patients with a positive and a negative family history was significant (t = -3.334, P = 0.03), being 27% greater in psoriasis patients without a family history. The differences in dermal papilla distances among patients were very small. We conclude that microscope-supported thickness measurements provide objective results.Öğe Neural Networks based modelling of traffic accidents in interurban rural highways, Düzce sampling(Asian Network for Scientific Information, 2008) Özgan, Ercan; Demirci, RecepIn this study, alternatively, Artificial Neural Network (ANN) based modelling of traffic accidents on two line interurban rural highways in terms of number of accidents, injuries and dead have been presented. This study was conducted for D100/11 state highway section in Düzce. In this section of the highway, totally 783 traffic accidents occurred and 1396 vehicles involved in these accidents between 2002 and 2006 years. Using traffic accident reports data, ANN was applied for modelling of traffic accidents with respect to distance and months. As a result, it was observed that there was a perfect fit between the simulation results and actual data of accidents and the created neural network model of accidents resembles the actual data. Therefore, the developed model could be an alternative method for predictions of traffic accidents on interurban rural highways. © 2008 Asian Network for Scientific Information.Öğe A novel edge detector based on light refraction law(Ieee, 2008) Güvenç, Uğur; Elmas, Çetin; Demirci, RecepIn this paper, light refraction law based a novel edge detection algorithm was described. In the proposed method, center pixel deemed a light source. Neighbor pixels are deemed different environments refracted the light. The minimum value of ratio of these different environments refraction indices qualifies the edge knowledge of center pixels. Edges are determined rigorously in the image through this designed method. As compared with classical method, there isn't very complex computing in this method.Öğe Renkli görüntülerin otomatik ayrıştırılması(2008) Güvenç, Uğur; Elmas, Çetin; Demirci, RecepBu makalede, renkli görüntüler için geliştirilen otomatik ayrıştırma algoritması sunulmuştur. Komşu piksellerin benzerlik yüzdeleri renk benzerlik ölçümü tabanlı matematiksel yaklaşım kullanılarak hesaplanmıştır. Önerilen yöntem, görüntüde muhtemel var olan bölge sayısı hakkında herhangi bir ön bilgiye ihtiyaç duymamaktadır. Böylece diğer metotlara göre ihtiyaç duyulan hesaplama yükü azaltılmıştır. Yapılan benzetim ve uygulamalarla önerilen yöntemin performansı test edilmiştirÖğe Segmentation of color images based on relation matrix(Ieee, 2007) Demirci, Recep; Katırcıoğlu, FerzanIn this study, segmentation is done by using the similarity feature between neighbour pixells. Image segmentation was not done on the original image, it was done on the similarity image, by using region growing algoritm. Distance and similarity measure functions and relation matrix are explained on similarity image. It was tried to answer the effect of similarity measure functions and how threshold and normality value effect the segmentation.Öğe Tekrarlı Ortalama Yardımıyla Renk İndirgeme ve Görüntü Erişimi(2020) Demirci, Recep; Tanyeri, Ufuk; Kılıçaslan, MahmutSayısal görüntülerden oluşan bir veri tabanından sorgulanan bir görüntünün aynısının veya benzerleriningetirilmesi süreci görüntü erişimi olarak tanımlanır. Her ne kadar sayısal görüntü piksellerden oluşuyor olsa dasorgulama piksel düzeyinde değil, sayısal görüntüleri temsil eden vektörler düzeyinde yapılmaktadır. Görüntülerinvektörler ile temsil edilmesi özellik çıkarma süreci olarak adlandırılır ve içerik tabanlı görüntü erişiminin (İTGE)en önemli aşamasıdır. Özellik vektörünün temsil kabiliyetinin düşük olması sistemin performansının da düşükolması demektir. Gri ölçekli görüntülerin histogramları en tipik özellik vektörleridir. Diğer taraftan renkligörüntülerde üç ayrı kanal mevcut olduğundan, görüntüyü temsil edebilecek histogram üç boyutlu bir dizioluşturur ki bu durum sistemin hesap maliyetini oldukça artıracaktır. Bu nedenle araştırmacılar renkligörüntülerdeki renk sayısını azaltma veya renk indirgeme yaklaşımını tercih etmişlerdir. Vektör kuantalama olarakadlandırılan renk indirgeme sürecinde ise her zaman aynı sonucu üretmek mümkün olmamıştır. Bunun nedeni isebazı algoritmaların başlangıçta rastgele üretilen renk vektörleri ile çözüm aramalarıdır. Linde-Buzo-Gray (LBG),K-ortalamalar ve bulanık c-ortalamalar algoritmaları bu tür çözüm yaklaşımlarına tipik örneklerdir. Bu çalışmadatekrarlı ortalama tabanlı renk indirgeme yaklaşımı kullanılarak yeni bir görüntü erişim metodu önerilmiştir.Önerilen stratejide, öncelikle her bir renk kanalının histogramı üzerinden tekrarlı bir şekilde ortalamalarhesaplanmış ve çok seviyeli eşikler elde edilmiştir. Elde edilen eşikler kullanılarak RGB renk uzayı alt prizmalarşeklinde dilimlenmiştir. Oluşan alt prizmalar içinde kalan pikseller aynı sınıfa atanmış ve ilgili sınıftaki piksellerinortalamaları kullanılarak renk indirgemesi yapılmıştır. Sınıf indisleri ve ilgili sınıflara tahsis edilen piksel sayılarıyardımıyla tek boyutlu histogram elde edilmiştir. Son aşamada ise elde edilen sınıf tabanlı histogram özellikvektörü olarak atanmış ve içerik tabanlı görüntü erişimi gerçekleştirilmiştir. Önerilen algoritma ve LBGalgoritması ile sonuçlar alınmış ve karşılaştırmalar yapılmıştır.Öğe Yön bağımsız yayınım filtresinin plaka görüntülerindeki gürültülerin temizlenmesindeki etkisi(2008) Elmas, Çetin; Demirci, Recep; Güvenç, UğurPlaka karakter tanıma, araçların plakaları vasıtasıyla tanınmasına yarayan bir görüntü işleme uygulamasıdır. Günümüzde plaka karakter tanıma için geliştirilen birçok görüntü işleme teknikleri kötü hava koşulları ve kirli plakalar yüzünden etkili sonuçlar verememektedir. Bu olumsuz yönleri yok etmek ve etkili bir sonuç alabilmek için ortalama, ortanca, wiener gibi çeşitli görüntü filtreleme teknikleri kullanılmaktadır. Ancak kullanılan bu filtreleme teknikleri görüntüdeki gürültüyü yok ederken orijinal görüntünün kenarlarında kalınlaşma ve bozulmalar meydana getirmektedir. Bu çalışmada, görüntüdeki gürültünün temizlenmesi için yön bağımsız yayınım filtreleme yöntemi, dört farklı yayınım fonksiyonu ile test edilmiştir. Yapılan testlerde, yön bağımsız yayınım filtreleme sonucu görüntüdeki en az bozulmanın Perona-Malik’in ikinci fonksiyonu kullanıldığında ortaya çıktığı görülmüştür.
