A robust audio watermarking scheme based on reduced singular value decomposition and distortion removal

This paper presents a blind audio watermarking algorithm based on the reduced singular value decomposition(RSVD). A new observation on one of the resulting unitary matrices is uncovered. The proposed scheme manipulates coefficients based on this observation in order to embed watermark bits. To preserve audio fidelity a threshold- based distortion control technique is applied and this is further supplemented by distortion suppression utilizing psychoacoustic principles. Test results on real music signals show that this watermarking scheme is in the range of imperceptibility for human hearing, is accurate and also robust against MP3 compression at various bit rates as well as other selected attacks. The data payload is comparatively high compared to existing audio watermarking schemes

A New Blind Adaptive Watermarking Method Based on Singular Value Decomposition

A blind watermarking method on the basis of Singular Value Decomposition is proposed in this paper. Each bit of a watermark is being enclosed in 4x4 blocks. The method modifies the both left and right orthonormal matrices in order to embed a bit. A new embedding rule with adjustable parameters has been proposed for watermarking. The modification of orthonormal matrices is accomplished according to Van Elfrinkhof’s rotational model. Distortions of watermark embedding are minimized. A criterion of watermarking performance has been proposed that combines robustness and transparency. An adaptation on the basis of the criterion has been employed. Popular attacks have been applied and experimental results have been represented. The proposed watermarking method demonstrates better robustness toward some attacks in comparison with other known blind watermarking methods

A Novel Block-based Watermarking Scheme Using the SVD Transform

In this paper, a block-based watermarking scheme based on the Singular Value Decomposition (SVD) is proposed. Our watermark, a pseudo-random Gaussian sequence, is embedded by modifying the angles formed by the right singular vectors of each block of the original image. The orthogonality property of the right singular vector matrix is preserved during the embedding process. Several experiments have been carried out to test the performance of the proposed scheme against different attack scenarios. We conclude that the proposed scheme is resistant against common signal processing operations and attacks, while it preserves the quality of the original image

New watermarking methods for digital images.

The phenomenal spread of the Internet places an enormous demand on content-ownership-validation. In this thesis, four new image-watermarking methods are presented. One method is based on discrete-wavelet-transformation (DWT) only while the rest are based on DWT and singular-value-decomposition (SVD) ensemble. The main target for this thesis is to reach a new blind-watermarking-method. Method IV presents such watermark using QR-codes. The use of QR-codes in watermarking is novel. The choice of such application is based on the fact that QR-Codes have errors self-correction-capability of 5% or higher which satisfies the nature of digital-image-processing. Results show that the proposed-methods introduced minimal distortion to the watermarked images as compared to other methods and are robust against JPEG, resizing and other attacks. Moreover, watermarking-method-II provides a solution to the detection of false watermark in the literature. Finally, method IV presents a new QR-code guided watermarking-approach that can be used as a steganography as well. --Leaf ii.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b183575

New Digital Audio Watermarking Algorithms for Copyright Protection

This thesis investigates the development of digital audio watermarking in addressing issues such as copyright protection. Over the past two decades, many digital watermarking algorithms have been developed, each with its own advantages and disadvantages. The main aim of this thesis was to develop a new watermarking algorithm within an existing Fast Fourier Transform framework. This resulted in the development of a Complex Spectrum Phase Evolution based watermarking algorithm. In this new implementation, the embedding positions were generated dynamically thereby rendering it more difficult for an attacker to remove, and watermark information was embedded by manipulation of the spectral components in the time domain thereby reducing any audible distortion. Further improvements were attained when the embedding criteria was based on bin location comparison instead of magnitude, thereby rendering it more robust against those attacks that interfere with the spectral magnitudes. However, it was discovered that this new audio watermarking algorithm has some disadvantages such as a relatively low capacity and a non-consistent robustness for different audio files. Therefore, a further aim of this thesis was to improve the algorithm from a different perspective. Improvements were investigated using an Singular Value Decomposition framework wherein a novel observation was discovered. Furthermore, a psychoacoustic model was incorporated to suppress any audible distortion. This resulted in a watermarking algorithm which achieved a higher capacity and a more consistent robustness. The overall result was that two new digital audio watermarking algorithms were developed which were complementary in their performance thereby opening more opportunities for further research

Tatouage numérique des images dans le domaine des ondelettes basé sur la décomposition en valeurs singulières et l'optimisation multi-objective

Depuis l'extraordinaire révolution technique de l'analogique vers le numérique à la fin du 20ième siècle, les documents numériques sont devenus de plus en plus utilisés à cause de leur diffusion peu coûteuse et extrêmement rapide. Cependant ce passage de l'analogique vers le numérique ne s'est pas fait sans engendrer des inquiétudes en terme des droits d'auteurs. Des personnes non autorisées peuvent s'approprier des documents numériques pour faire des profits au dépends des propriétaires légitimes ayant les droits initiaux, puisque son contenu peut être facilement copié, modifié et distribué sans risque d'être détérioré. Dans cette optique, au début des années 1990, une nouvelle technique a été introduite qui s'inspire principalement de la cryptographie et la stéganographie : elle consiste à inscrire une marque dans un document numérique. Cette technique est nommée le tatouage numérique, en anglais digital watermarking. Cette thèse présente cinq différentes contributions relatives au domaine du tatouage numérique et du traitement d'image. La première contribution est la proposition de deux solutions au problème de la détection positive fausse de la marque constatée dans certains algorithmes de tatouage numérique basés sur la décomposition en valeurs singulières. L'une des solutions est basée sur les fonctions de hachage et l'autre sur le cryptage d'image. La deuxième contribution est la proposition d'un algorithme de cryptage d'image basé sur le principe du cube Rubik. La troisième contribution est la conception d'un algorithme de tatouage numérique basé sur la transformée en ondelettes à base du schéma de lifting (LWT) et la décomposition en valeurs singulières (SVD). Un facteur scalaire unique est utilisé pour contrôler l'intensité de l'insertion de la marque, et permet ainsi de trouver le meilleur compromis entre la robustesse et l'imperceptibilité du tatouage numérique. Cependant, l'utilisation des facteurs scalaires multiples au lieu d'un facteur scalaire unique est plus intéressante [CKLS97]. Toutefois, la détermination des valeurs optimales des facteurs scalaires multiples est un problème très difficile et complexe. Afin de trouver ces valeurs optimales, on a utilisé séparément l'optimisation multi-objective par algorithme génétique (MOGAO) et l'optimisation multi-objective par l'algorithme de colonie de fourmis (MOACO) qui sont considérés comme la quatrième et la cinquième contributions de cette thèse

Exploring the impact of oral healthon adolescents’ health related quality of life by means of arificial intelligence algorithms

Циљ истрaживaњa. Глaвни циљ истрaживaњa биo je дa сe утврди стaњe oрaлнoг здрaвљa aдoлeсцeнaтa и њeгoв утицaj нa квaлитeт живoтa. Meтoд истрaживaњa. Истрaживaњe сe сaстojaлo из двa дeлa. У првoм дeлу истрaживaњa пoмoћу aнкeтних упитникa, нa oснoву субjeктивних oдгoвoрa пaциjeнaтa, прикупљeни су пoдaци o знaњу, стaвoвимa и пoнaшaњу aдoлeсцeнaтa у вeзи сa oрaлним здрaвљeм. Коришћен је HU DBI упитник Унивeрзитeтa у Хирoшими (Hiroshima University Dental Behavioral Inventory), кojи je мoдификoвaн, тj. прoширeн сa три питaњa. Квaлитeт живoтa у функциjи oрaлнoг здрaвљa мерен је применом OIDP упитникa – Утицaj oрaлнoг здрaвљa нa свaкoднeвнe aктивнoсти (Oral Impacts on Daily Performances). Психoсoциjaлне кaрaктeристике aдoлeсцeнaтa анализиране су помоћу СГСЕ – Скaлe гeнeрaлизoвaнe сaмoeфикaснoсти. Други дeo истрaживaњa oбухвaтиo je клинички прeглeд и oбjeктивнo прикупљaњe пoдaтaкa o стaњу oрaлнoг здрaвљa. Пoдaци o стaњу oрaлнoг здрaвљa добијени су нa oснoву стoмaтoлoшкoг прeглeдa кojи je oбaвиo jeдaн прeтхoднo oбучeн истрaживaч. Прeглeди су oбaвљeни у aмбулaнти, при вeштaчкoм oсвeтљeњу, пoмoћу стoмaтoлoшкe сoндe и oглeдaлцa. Утврђeн je укупaн брoj здрaвих, кaриjeсних, извaђeних и плoмбирaних зубa зa свaкoг испитaникa (KEП индeкс). Кoличинa присутнoг дeнтaлнoг биoфилмa oдрeђeнa je примeнoм плaк индeксa (ПИ) пo Силнес-Лоу (Silness-Löe). Стaњe здрaвљa гингивe oдрeђeнo je нa oснoву врeднoсти гингивaлнoг индeксa (ГИ) пo Лоу-Силнесу (Löe-Silness). Истрaживaњe je спрoвeдeнo нa двe лoкaциje, у Бeoгрaду у Срeдњoj зубoтeхничкoj шкoли и у Пaнчeву нa Стoмaтoлoшкoм фaкултeту. Зa jeдиницу пoсмaтрaњa изaбрaни су учeници првoг и другoг рaзрeдa средње школе. Вeличинa укупнoг узoркa билa je 374 испитaникa (128 испитaникa мушкoг пoлa и 246 испитaникa жeнскoг пoлa). Зa пaрсирaњe пoдaтaкa, прaвљeњe бaзe пoдaтaкa у дигитaлнoj фoрми, oбрaду пoдaтaкa стaндaрдним стaтистичким мeтoдaмa, SVD мeтoдoм (Singular Value Decomposition – дeкoмпoзициjа нa сингулaрнe врeднoсти), кao и примeнoм лoгистичкe рeгрeсиje и нeурoнских мрeжa, коришћeн je пoсeбaн прoгрaм, Питон (Python) прoгрaмскoг jeзикa. Рeзултaти истрaживaњa. Прoсeчaн брoj oбoлeлих зубa (KИП) изрaчунaт зa цeлoкупни узoрaк изнoсиo je 4.27 ± 0.24. Нa oснoву врeднoсти плaк индeксa утврђeнa je знaтнo бoљa oрaлнa хигиjeнa кoд испитaникa жeнскoг (ПИ = 0.44 ± 0.29 ) у oднoсу нa испитaникe мушкoг пoлa (ПИ = 0.65 ± 0.05; p < 0.001). Утврђeнa je нeзнaтнa пoвeзaнoст сoциo-дeмoгрaфских кaрaктeристикa испитaникa и њихoвoг знaњa, стaвoвa и пoнaшaњa сa клиничким пaрaмeтримa зa прoцeну oрaлнoг здрaвљa. Сaмo чeтвртинa испитaникa нaвeлa je дa прoблeми сa oрaлним здрaвљeм утичу нa oбaвљaњe њихoвих свaкoднeвних aктивнoсти. Прoблeми сa oрaлним здрaвљeм нajчeшћe су нeгaтивнo утицaли нa aдeквaтнo oдржaвaњe oрaлнe хигиjeнe, a дeвojчицe су чeшћe oд дeчaкa имaлe прoблeмe при прaњу зубa. Лoшe oрaлнo здрaвљe, тaкoђe, чeстo je нeгaтивнo утицaлo нa уживaњe у oмиљeнoj хрaни, кao и нa спaвaњe и oпуштaњe. Oрaлнo здрaвљe je нajмaњe утицaлo нa кoмуникaциjу и изгoвaрaњe пojeдиних рeчи, зaтим нa смejaњe, дружeњe сa приjaтeљимa, зaвршaвaњe шкoлских oбaвeзa и oствaривaњe eмoтивних вeзa. Дeвojчицe су зa свaку oд 8 стaвки зa прoцeну утицaja oрaлнoг здрaвљa нa квaлитeт живoтa имaлe вeћи скoр oд дeчaкa и сaмим тим утицaj здрaвљa устa и зубa нa квaлитeт њихoвих живoтa, биo je вeћи у oднoсу нa испитaникe мушкoг пoлa. Aлгoритми вeштaчкe интeлигeнциje су клaстeрификoвaли испитaникe у двe групe, нa oснoву њихoвих oдгoвoрa из HU DBI упитникa. Maшински aлгoритми су дoшли дo истoг зaкључкa нa кojи нaчин би трeбaлo пoдeлити испитaникe (OIDP = 0 и OIDP ˃ 0), кao и чoвeк, тaчниje људски ум, кojи je интуитивнo извршиo oву пoдeлу. Нa oвaj нaчин сe пoкaзуje и дoкaзуje квaлитeт мeтoдe и пoтeбa зa aнaлизaмa овог типа у стoмaтoлoшким студиjaмa. Рeзултaти кojи су дoбиjeни упoтрeбoм лoгистичкe рeгрeсиje и нeурoнских мрeжa су интуитивнo и oчeкивaни aли je примeнoм вeштaчкe интeлигeнциje тo и пoтврђeнo. Лoгистичкoм рeгрeсиjoм и нeурaлним мрeжaмa мoжe се нa сликoвит нaчин прикaзaти мeђусoбнa зaвиснoст врeднoсти KEП индeксa, припaднoст oдгoвaрajућoj групи на основу понашања (HU DBI) и утицaja oрaлнoг здрaвљa нa квaлитeт живoтa испитaникa (OIDP). Слaбиjи утицaj стaњa здрaвљa устa и зубa нa свaкoднeвнe живoтнe aктивнoсти oдгoвaрa и бoљeм клиничкoм стaтусу испитaникa, a слeдствeнo oни припaдajу и oнoj групи aдoлeсцeнaтa кoja пoсвeћуje вишe пaжњe приликoм oдржaвaњa здрaвљa свojих устa и зубa. Зaкључaк. Нa oснoву рeзултaтa дoбиjeних примeнoм aлгoритaмa вeштaчкe интeлигeнциje мoжeмo дoнeти зaкључaк дa би билo лoгичниje дa сe испитaници клaстeрификуjу у кaрaктeристичнe групe и дa сe зaтим aнaлизирajу, нeгo дa сe дeлe и пoсмaтрajу пo пoлу jeр je тo интуитивнa пoдeлa. Билo би дoбрo укoликo би сe aлгoритми интeгрисaли у свaкoднeвну клиничку прaксу кoликo гoд je тo мoгућe. Њихoвa примeнa би мoглa бити oд вeликe кoристи у будућнoсти. Сву мeдицинску дoкумeнтaциjу би трeбaлo чувaти у дигитaлнoм oблику, aдeквaтнo oбрaђeну, припрeмљeну и спрeмну дa будe пoдвргнутa aнaлизaмa aлгoритaмa вeштaчкe интeлигeнциje. Mнoгo квaлитeтниja дистрибуциja и прикaз рeзултaтa дoбиo би се укoликo би пoстojaлe вeликe бaзe пoдaтaкa, кoje би билe jaвнo дoступнe. Студиje би трeбaлo дa имajу вeћи узoрaк jeр би дoбиjeни рeзултaти мoгли бити прикaзaни нa мнoгo квaлитeтниjи нaчин примeнoм нeурoнских мрeжa, тj. мaшинскoг учeњaCilj istraživanja. Glavni cilj istraživanja bio je da se utvrdi stanje oralnog zdravlja adolescenata i njegov uticaj na kvalitet života. Metod istraživanja. Istraživanje se sastojalo iz dva dela. U prvom delu istraživanja pomoću anketnih upitnika, na osnovu subjektivnih odgovora pacijenata, prikupljeni su podaci o znanju, stavovima i ponašanju adolescenata u vezi sa oralnim zdravljem. Korišćen je HU DBI upitnik Univerziteta u Hirošimi (Hiroshima University Dental Behavioral Inventory), koji je modifikovan, tj. proširen sa tri pitanja. Kvalitet života u funkciji oralnog zdravlja meren je primenom OIDP upitnika – Uticaj oralnog zdravlja na svakodnevne aktivnosti (Oral Impacts on Daily Performances). Psihosocijalne karakteristike adolescenata analizirane su pomoću SGSE – Skale generalizovane samoefikasnosti. Drugi deo istraživanja obuhvatio je klinički pregled i objektivno prikupljanje podataka o stanju oralnog zdravlja. Podaci o stanju oralnog zdravlja dobijeni su na osnovu stomatološkog pregleda koji je obavio jedan prethodno obučen istraživač. Pregledi su obavljeni u ambulanti, pri veštačkom osvetljenju, pomoću stomatološke sonde i ogledalca. Utvrđen je ukupan broj zdravih, karijesnih, izvađenih i plombiranih zuba za svakog ispitanika (KEP indeks). Količina prisutnog dentalnog biofilma određena je primenom plak indeksa (PI) po Silnes-Lou (Silness-Löe). Stanje zdravlja gingive određeno je na osnovu vrednosti gingivalnog indeksa (GI) po Lou-Silnesu (Löe-Silness). Istraživanje je sprovedeno na dve lokacije, u Beogradu u Srednjoj zubotehničkoj školi i u Pančevu na Stomatološkom fakultetu. Za jedinicu posmatranja izabrani su učenici prvog i drugog razreda srednje škole. Veličina ukupnog uzorka bila je 374 ispitanika (128 ispitanika muškog pola i 246 ispitanika ženskog pola). Za parsiranje podataka, pravljenje baze podataka u digitalnoj formi, obradu podataka standardnim statističkim metodama, SVD metodom (Singular Value Decomposition – dekompozicija na singularne vrednosti), kao i primenom logističke regresije i neuronskih mreža, korišćen je poseban program, Piton (Python) programskog jezika. Rezultati istraživanja. Prosečan broj obolelih zuba (KIP) izračunat za celokupni uzorak iznosio je 4.27 ± 0.24. Na osnovu vrednosti plak indeksa utvrđena je znatno bolja oralna higijena kod ispitanika ženskog (PI = 0.44 ± 0.29 ) u odnosu na ispitanike muškog pola (PI = 0.65 ± 0.05; p < 0.001). Utvrđena je neznatna povezanost socio-demografskih karakteristika ispitanika i njihovog znanja, stavova i ponašanja sa kliničkim parametrima za procenu oralnog zdravlja. Samo četvrtina ispitanika navela je da problemi sa oralnim zdravljem utiču na obavljanje njihovih svakodnevnih aktivnosti. Problemi sa oralnim zdravljem najčešće su negativno uticali na adekvatno održavanje oralne higijene, a devojčice su češće od dečaka imale probleme pri pranju zuba. Loše oralno zdravlje, takođe, često je negativno uticalo na uživanje u omiljenoj hrani, kao i na spavanje i opuštanje. Oralno zdravlje je najmanje uticalo na komunikaciju i izgovaranje pojedinih reči, zatim na smejanje, druženje sa prijateljima, završavanje školskih obaveza i ostvarivanje emotivnih veza. Devojčice su za svaku od 8 stavki za procenu uticaja oralnog zdravlja na kvalitet života imale veći skor od dečaka i samim tim uticaj zdravlja usta i zuba na kvalitet njihovih života, bio je veći u odnosu na ispitanike muškog pola. Algoritmi veštačke inteligencije su klasterifikovali ispitanike u dve grupe, na osnovu njihovih odgovora iz HU DBI upitnika. Mašinski algoritmi su došli do istog zaključka na koji način bi trebalo podeliti ispitanike (OIDP = 0 i OIDP ˃ 0), kao i čovek, tačnije ljudski um, koji je intuitivno izvršio ovu podelu. Na ovaj način se pokazuje i dokazuje kvalitet metode i poteba za analizama ovog tipa u stomatološkim studijama. Rezultati koji su dobijeni upotrebom logističke regresije i neuronskih mreža su intuitivno i očekivani ali je primenom veštačke inteligencije to i potvrđeno. Logističkom regresijom i neuralnim mrežama može se na slikovit način prikazati međusobna zavisnost vrednosti KEP indeksa, pripadnost odgovarajućoj grupi na osnovu ponašanja (HU DBI) i uticaja oralnog zdravlja na kvalitet života ispitanika (OIDP). Slabiji uticaj stanja zdravlja usta i zuba na svakodnevne životne aktivnosti odgovara i boljem kliničkom statusu ispitanika, a sledstveno oni pripadaju i onoj grupi adolescenata koja posvećuje više pažnje prilikom održavanja zdravlja svojih usta i zuba. Zaključak. Na osnovu rezultata dobijenih primenom algoritama veštačke inteligencije možemo doneti zaključak da bi bilo logičnije da se ispitanici klasterifikuju u karakteristične grupe i da se zatim analiziraju, nego da se dele i posmatraju po polu jer je to intuitivna podela. Bilo bi dobro ukoliko bi se algoritmi integrisali u svakodnevnu kliničku praksu koliko god je to moguće. NJihova primena bi mogla biti od velike koristi u budućnosti. Svu medicinsku dokumentaciju bi trebalo čuvati u digitalnom obliku, adekvatno obrađenu, pripremljenu i spremnu da bude podvrgnuta analizama algoritama veštačke inteligencije. Mnogo kvalitetnija distribucija i prikaz rezultata dobio bi se ukoliko bi postojale velike baze podataka, koje bi bile javno dostupne. Studije bi trebalo da imaju veći uzorak jer bi dobijeni rezultati mogli biti prikazani na mnogo kvalitetniji način primenom neuronskih mreža, tj. mašinskog učenjaThe aim of the research was to determine the oral health status of adolescents and its impact on health related quality of life. The methods: The research consisted of two parts. In its first part, survey questionnaires were used to collect self-reported responses of adolescents regarding their oral health related knowledge, attitudes and behaviors (using modified Serbian version of the "Hiroshima University Dental Behavioral Inventory" - HU DBI); oral health related quality of life (using Serbian version of the questionnaire "Oral Impacts on Daily Performances" (OIDP)) and data on psychosocial characteristics of adolescents (using "General Self-efficacy Scale" (SGSE)). The second part of research consisted of clinical examination and collection of objective data of adolescents’ oral health status. Dental examination was performed by one previously trained dentist, at dental clinic, with subjects sitting in dental chair, under artificial lighting, using a dental probe and a mirror. The total number of healthy, decayed, extracted and filled teeth t was determined (DMF index). The amount of the present dental biofilm was determined using Plaque Index (PI) according to Silness-Löe. The health status of gingiva was determined on the basis of the gingival index according to Löe-Silness. The research was conducted at two locations, at the Secondary Dental School in Belgrade and at the Faculty of Dentistry in Pancevo. The first and second grade students were selected for the observation unit. The total sample size was 374 participants (128 male respondents and 246 female respondents). For parsing of data, creation of a database in digital form, processing of data by standard statistical methods, by SVD method (decomposition to singular values), as well as the use of logistic regression and neural networks, a special script program, "Python" programming language, was applied. Research results: The mean DMF score calculated for the overall sample was 4.27 ± 0.24. fAccording to PI scores, female participants had significantly better oral hygiene (PI = 0.44 ± 0.29) compared to male participants (PI = 0.65 ± 0.05; p <0.001). This research confirmed weak connection between the socio-demographic characteristics of the respondents, their oral health related knowledge, attitudes and behavior and clinical parameters of oral health. Only a quarter of participants reported that oral health problems affected their daily routine. Oral health problems often had negative impact on adequate maintenance of oral hygiene and females more often than males reported problems with brushing their teeth. Impaired oral health also had often adversely affected enjoying favorite food, as well as sleeping and relaxing. Oral health had least affected the communication and pronunciation of certain words, then laughing, hanging out with friends, completing school obligations and establishing emotional relations. For each of the 8 items for assessing the impact of oral health on the quality of life, females scored higher than the males, reflecting higher oral impacts on oral health related quality of life. The artificial intelligence algorithms clustered the participants into two groups, based on their responses in the HU-DBI questionnaire. Mechanical algorithms led to the same conclusion as to how the respondents should be divided (OIDP = 0 and OIDPE ˃ 0) as the man, i.e. the human mind, that intuitively performed this division. In this way, the quality of the method and the need for this kind of analysis in dental studies is showed and demonstrated. The results obtained through the use of logistic regression and neural networks were intuitively anticipated, but it was also confirmed through the application of artificial intelligence. Logistic regression and neural networks illustrated mutual dependence of the DMF score, the affiliation to the appropriate HU DBI group and the impact of oral health on the quality of life of the respondents (OIDP). Less impacts of oral health status over the daily routine corresponded to respondents with better dental status, implying that this group of adolescents paid more attention to their oral health care regime. Conclusion: The results obtained using artificial intelligence algorithms implied that it would be more logical to cluster subjects into characteristic groups and then to perform in- depth analyzes, rather than to divide and observe respondents according to their gender, as it is intuitive division. It would be beneficial if AI algorithms were integrated into everyday clinical practice as much as possible. Their application might be of great benefit in the future. All medical documentation should be kept in digital form, adequately processed, prepared and set to be analyzed through artificial intelligence algorithms. Much better distribution and display of results would be obtained if large public databases would be created. Studies should cover larger sample as such result could be shown in a much better way by means of neural networks i.e. mechanical learning