Development of Color Difference Equations Matching to Human Vision System

Research on color difference evaluation has been active in recent thirty years. Several color difference formulas were developed for industrial applications. The aims of this thesis are to develop the color density which is denoted by comb g and to propose the color density based chromaticity difference formulas. Color density is derived from the discrimination ellipse parameters and color positions in the xy , xyY and CIELAB color spaces, and the color based chromaticity difference formulas are compared with the line element formulas and CIE 2000 color difference formulas. As a result of the thesis, color density represents the perceived color difference accurately, and it could be used to characterize a color by the attribute of perceived color difference from this color.

Kromaattisuuserojen laskentamalli

Työssä esitellään Lappeenrannan teknillisen yliopiston Tietotekniikan osastolla kehitettyä kromaattisuuserojen laskentamallia. Työn keskeisimpinä tavoitteina on luoda tiivis katsaus jo olemassa oleviin värierojen laskentamenetelmien tekniikoihin ja käydä läpi värien havaitsemiseen liittyviä yksityiskohtia. Työn käytännön osuudessa tutkitaan kehitettyä mallia ja esitetään ideoita kehittäen mallia täsmällisemmäksi. Kromaattisuuserojen laskentamalli perustuu MacAdamin määrittelemien ellipsien hyödyntämiseen CIE-1931 kromaattisuusdiagrammissa. Ideana on projisoida ellipsit iso- ja pikkuakseleidensa suhteen vakiosäteisiksi ympyröiksi kolmiulotteiselle pinnalle. Kromaattisuuserot lasketaan pinnalta käyttämällä numeerista menetelmää. Tuloksena todetaan mallin täyttävän osittain sille asetetut vaatimukset ja parantavan CIE-1931 kromaattisuusdiagrammin yhtenäisyyttä erityisesti diagrammin vihreän ja sinisen värin alueilla.

Performance Evaluation and Calibration of Machine Vision Measurement

This thesis presents the calibration and comparison of two systems, a machine vision system that uses 3 channel RGB images and a line scanning spectral system. Calibration. is the process of checking and adjusting the accuracy of a measuring instrument by comparing it with standards. For the RGB system self-calibrating methods for finding various parameters of the imaging device were developed. Color calibration was done and the colors produced by the system were compared to the known colors values of the target. Software drivers for the Sony Robot were also developed and a mechanical part to connect a camera to the robot was also designed. For the line scanning spectral system, methods for the calibrating the alignment of the system and the measurement of the dimensions of the line scanned by the system were developed. Color calibration of the spectral system is also presented.

Computational Evaluation of Print Unevenness According to Human Vision

Print quality and the printability of paper are very important attributes when modern printing applications are considered. In prints containing images, high print quality is a basic requirement. Tone unevenness and non uniform glossiness of printed products are the most disturbing factors influencing overall print quality. These defects are caused by non ideal interactions of paper, ink and printing devices in high speed printing processes. Since print quality is a perceptive characteristic, the measurement of unevenness according to human vision is a significant problem. In this thesis, the mottling phenomenon is studied. Mottling is a printing defect characterized by a spotty, non uniform appearance in solid printed areas. Print mottle is usually the result of uneven ink lay down or non uniform ink absorption across the paper surface, especially visible in mid tone imagery or areas of uniform color, such as solids and continuous tone screen builds. By using existing knowledge on visual perception and known methods to quantify print tone variation, a new method for print unevenness evaluation is introduced. The method is compared to previous results in the field and is supported by psychometric experiments. Pilot studies are made to estimate the effect of optical paper characteristics prior to printing, on the unevenness of the printed area after printing. Instrumental methods for print unevenness evaluation have been compared and the results of the comparison indicate that the proposed method produces better results in terms of visual evaluation correspondence. The method has been successfully implemented as ail industrial application and is proved to be a reliable substitute to visual expertise.

Retinal Image Analysis Using Machine Vision

The topic of this thesis is studying how lesions in retina caused by diabetic retinopathy can be detected from color fundus images by using machine vision methods. Methods for equalizing uneven illumination in fundus images, detecting regions of poor image quality due toinadequate illumination, and recognizing abnormal lesions were developed duringthe work. The developed methods exploit mainly the color information and simpleshape features to detect lesions. In addition, a graphical tool for collecting lesion data was developed. The tool was used by an ophthalmologist who marked lesions in the images to help method development and evaluation. The tool is a general purpose one, and thus it is possible to reuse the tool in similar projects.The developed methods were tested with a separate test set of 128 color fundus images. From test results it was calculated how accurately methods classify abnormal funduses as abnormal (sensitivity) and healthy funduses as normal (specificity). The sensitivity values were 92% for hemorrhages, 73% for red small dots (microaneurysms and small hemorrhages), and 77% for exudates (hard and soft exudates). The specificity values were 75% for hemorrhages, 70% for red small dots, and 50% for exudates. Thus, the developed methods detected hemorrhages accurately and microaneurysms and exudates moderately.

Evaluation of Routing solution for Next Generation Open Platform

Verkkoon kytkettävien laitteiden määrä on lisääntynyt viime vuosina, joka luo tarpeen reitittimille ja niiden ominaisuuksille. On muodostunut uusi tarve laitteille, jotka voivat yhdistää erilaisia verkkoja toisiinsa. Tällaisen reitittimen rakentamiseen tarvitaan vakaa alusta. Tällaisella alustalla luodaan mahdollisuus kuormittaa järjestelmää ilman suuria ongelmia. Tällainen alusta on Open Platform, joka on suunniteltu tällaisille toiminnoille ja yhdessä oikeanlaisen verkkoratkaisun kanssa sitä voidaan käyttää sille suunnitellussa ympäristössä. Tämän diplomityön tarkoituksena on arvioida neljää eri reititysohjelmistoa ja kahta eri IP pinoa. Työssä käytetyt testit on suunniteltu arviointia varten ja niiden tarkoituksena on tuoda esille ohjelmistoissa esiintyvät viat ja ongelmat. Kaikki testit ovat samoja kaikille ohjelmille ja tehdään samassa ympäristössä. Testit analysoidaan niiden ajon jälkeen ja niiden tulosten avulla tehdään päätös mitä näistä ohjelmistoista tullaan käyttämään seuraavan sukupolven avoimella alustalla, joka tulee toimimaan Nokian Intelligent Service Nodessa. Tämä verkon laite toimii yhdyskäytävänäerilaisten verkkojen välillä.

Optinen kolmiulotteinen mittaus ohutlevytuotteiden laadunvalvonnassa

Ohutlevyteollisuuden markkinatilanne on muuttunut, kun tuotantomäärät ovat kasvaneet, laatuvaatimukset tiukentuneet ja markkinat globalisoituneet. Konenäön avulla on mahdollista tehostaa laadunvalvontaa, jolloin virheet voidaan havaita nopeammin ja siten säästää tuotantokustannuksissa. Muotoiltujen ohutlevyosien tarkastamiseksi tarvitaan kolmiulotteisia mittausmenetelmiä, joilla pystytään varsin nopeasti ja tarkasti analysoimaan kappaleita. Erityisesti fotogrammetriaan perustuvaa rakenteista valoa on sovellettu erilaisissa mittalaitteissa, ja menetelmä on myös varsin joustava sekä edullinen käyttää. Fotogrammetriaan ja rakenteiseen valoon perustuvista mittalaitteista valittiin arvioitavaksi Mapvision 4D. Testeissä tutkittiin laitteen tarkkuutta, nopeutta ja soveltuvuutta teollisuusympäristöön sekä erityisesti taivutuskulmien, reikien halkaisijoidenja etäisyyksien mittaamista. Sovittamalla mitattu data CAD-malliin pystytään kappaleen mitoitus tarkastamaan vaaditulla 0,1 millimetrin tarkkuudella. Testitulosten perusteella voidaan todeta sekä mittalaitteen että mittausmenetelmän soveltuvan ohutlevykappaleiden laadunvalvontaan, kunhan reunojen määrityksessä esiintyvä säännöllinen epätarkkuus otetaan huomioon.

Project for Active and Robot Vision Course

Tässä työssä raportoidaan harjoitustyön kehittäminen ja toteuttaminen Aktiivisen- ja robottinäön kurssille. Harjoitustyössä suunnitellaan ja toteutetaan järjestelmä joka liikuttaa kappaleita robottikäsivarrella kolmiuloitteisessa avaruudessa. Kappaleidenpaikkojen määrittämiseen järjestelmä käyttää digitaalisia kuvia. Tässä työssä esiteltävässä harjoitustyötoteutuksessa käytettiin raja-arvoistusta HSV-väriavaruudessa kappaleiden segmentointiin kuvasta niiden värien perusteella. Segmentoinnin tuloksena saatavaa binäärikuvaa suodatettiin mediaanisuotimella kuvan häiriöiden poistamiseksi. Kappaleen paikkabinäärikuvassa määritettiin nimeämällä yhtenäisiä pikseliryhmiä yhtenäisen alueen nimeämismenetelmällä. Kappaleen paikaksi määritettiin suurimman nimetyn pikseliryhmän paikka. Kappaleiden paikat kuvassa yhdistettiin kolmiuloitteisiin koordinaatteihin kalibroidun kameran avulla. Järjestelmä liikutti kappaleita niiden arvioitujen kolmiuloitteisten paikkojen perusteella.

Evaluation of GPRS Radio Link Control Layer in Weak RF Field

General Packet Radio Service (GPRS) mahdollistaa pakettimuotoisen tiedonsiirron GSM-verkossa. Se tarjoaa yhteyden pakettidataverkkoihin, nostaen samalla tiedonsiirtonopeutta radiorajapinnassa. Radioresurssit ovat varattuna vain silloin kun on jotain lähetettävää, tehden täten radioresurssien käytön paljon tehokkaammaksi. Tämä diplomityö keskittyy GPRS protokollaan ja erityisesti sen datapinossa olevaan Radio Link Control (RLC) kerrokseen. RLC-kerros huolehtii GPRS- puhelimen ja tukiaseman välisen yhteyden luotettavuudesta. Työn tavoitteena on tutkia RLC-kerroksen toiminnallisuutta ja sen luotettavuutta heikossa kentässä, sekä selvittää heikon kentän vaikutusta uudelleenlähetyksiin. Työn tuloksena saadaan arvio signaalin voimakkuuden sekä uudelleen lähetysten vaikutuksesta GPRS:n datansiirtonopeuteen. Tämä työ käsittelee myös lyhyesti GSM-järjestelmää, koska lukijan on näin helpompaa ymmärtää myös GPRS-järjestelmän vaatimia teknisiä muutoksia. Tämä diplomityö on tehty osana Nokia Matkapuhelimet Oyj:ssä käynnissä olevaa GPRS tuotekehitysprojektia. Työn tuloksia käytetään testauksen tukena ja niitä on käytetty apuna RLC-kerroksen luotettavuustestauksen suunnittelussa.

Business potential evaluation of wireless local area networks: Teleoperator’s view

The objective of the thesis was to evaluate business potential of wireless local area networks (WLAN, Wireless LAN). At first, the scope of business potential evaluation of technology was introduced. Next, a general framework of business potential evaluation of technology based on literature was presented. In addition, convergence of cellular networks and data networks was studied in order to get an insight of current situation of mobile telecommunications industry. Finally, wireless local area networks business potential was evaluated. A wireless local area network is a data communication system, which combines data connectivity with mobility and is implemented in unlicensed frequency bands, allowing new business opportunities to emerge. The main markets of WLAN are corporate networks, public area networks and access networks. At the moment the penetration of WLAN terminals is low which derives to low demand of wireless LAN services. In addition, unlicensed spectrum forces the teleoperators to set the service price relatively low. The business potential is in integrating wireless LANs to cellular networks and in offering value added services to end users. The future of wireless LAN is to be complementary network to cellular networks. In this vision cellular networks provide voice and low data services and broadband wireless networks enable multimedia services.

Spectral Color Appearance Modeling

Kuvien laatu on tutkituimpia ja käytetyimpiä aiheita. Tässä työssä tarkastellaan värin laatu ja spektrikuvia. Työssä annetaan yleiskuva olemassa olevista pakattujen ja erillisten kuvien laadunarviointimenetelmistä painottaen näiden menetelmien soveltaminen spektrikuviin. Tässä työssä esitellään spektriväriulkomuotomalli värikuvien laadunarvioinnille. Malli sovelletaan spektrikuvista jäljennettyihin värikuviin. Malli pohjautuu sekä tilastolliseen spektrikuvamalliin, joka muodostaa yhteyden spektrikuvien ja valokuvien parametrien välille, että kuvan yleiseen ulkomuotoon. Värikuvien tilastollisten spektriparametrien ja fyysisten parametrien välinen yhteys on varmennettu tietokone-pohjaisella kuvamallinnuksella. Mallin ominaisuuksien pohjalta on kehitetty koekäyttöön tarkoitettu menetelmä värikuvien laadunarvioinnille. On kehitetty asiantuntija-pohjainen kyselymenetelmä ja sumea päättelyjärjestelmä värikuvien laadunarvioinnille. Tutkimus osoittaa, että spektri-väri –yhteys ja sumea päättelyjärjestelmä soveltuvat tehokkaasti värikuvien laadunarviointiin.

Offset-print mottling measurement using machine vision

Mottling is one of the key defects in offset-printing. Mottling can be defined as unwanted unevenness of print. In this work, diameter of a mottle spot is defined between 0.5-10.0 mm. There are several types of mottling, but the reason behind the problem is still not fully understood. Several commercial machine vision products for the evaluation of print unevenness have been presented. Two of these methods used in these products have been implemented in this thesis. The one is the cluster method and the other is the band-pass method. The properties of human vision system have been taken into account in the implementation of these two methods. An index produced by the cluster method is a weighted sum of the number of found spots, and an index produced by band-pass method is a weighted sum of coefficients of variations of gray-levels for each spatial band. Both methods produce larger indices for visually poor samples, so they can discern good samples from the poor ones. The difference between the indices for good and poor samples is slightly larger produced by the cluster method. 11 However, without the samples evaluated by human experts, the goodness of these results is still questionable. This comparison will be left to the next phase of the project.

Performance Evaluation of Imaging Systems

Imaging systems have developed latest years and developing is still continuing following years. Manufacturers of imaging systems give promises for the quality of the performance of imaging systems to advertise their products. Promises for the quality of the performance are often so good that they will not be tested in normal usage. The main target in this research is to evaluate the quality of the performance of two imaging systems: Scanner and CCD color camera. Optical measurement procedures were planned to evaluate the quality of imaging performances. Other target in this research is to evaluate calibration programs for the camera and the scanner. Measuring targets had to choose to evaluate the quality of imaging performances. Manufacturers have given definitions for targets. The third task in this research is to evaluate and consider how good measuring targets are.

Evaluation of Teacher Education Programs by Students and Graduates

The purpose of this research was to do a repeated cross-sectional research on class teachers who study in the 4th year and also graduated at the Faculty of Education, University of Turku between the years of 2000 through 2004. Specifically, seven research questions were addressed to target the main purpose of the study: How do class teacher education masters’ degree senior students and graduates rate “importance; effectiveness; and quality” of training they have received at the Faculty of Education? Are there significant differences between overall ratings of importance; effectiveness and quality of training by year of graduation, sex, and age (for graduates) and sex and age (for senior students)? Is there significant relationship between respondents’ overall ratings of importance; effectiveness and their overall ratings of the quality of training and preparation they have received? Are there significant differences between graduates and senior students about importance, effectiveness, and quality of teacher education programs? And what do teachers’ [Graduates] believe about how increasing work experience has changed their opinions of their preservice training? Moreover the following concepts related to the instructional activities were studied: critical thinking skills, communication skills, attention to ethics, curriculum and instruction (planning), role of teacher and teaching knowledge, assessment skills, attention to continuous professional development, subject matters knowledge, knowledge of learning environment, and using educational technology. Researcher also tried to find influence of some moderator variables e.g. year of graduation, sex, and age on the dependent and independent variables. This study consisted of two questionnaires (a structured likert-scale and an open ended questionnaire). The population in study 1 was all senior students and 2000-2004 class teacher education masters’ degree from the departments of Teacher Education Faculty of Education at University of Turku. Of the 1020 students and graduates the researcher was able to find current addresses of 675 of the subjects and of the 675 graduates contacted, 439 or 66.2 percent responded to the survey. The population in study 2 was all class teachers who graduated from Turku University and now work in the few basic schools (59 Schools) in South- West Finland. 257 teachers answered to the open ended web-based questions. SPSS was used to produce standard deviations; Analysis of Variance; Pearson Product Moment Correlation (r); T-test; ANOVA, Bonferroni post-hoc test; and Polynomial Contrast tests meant to analyze linear trend. An alpha level of .05 was used to determine statistical significance. The results of the study showed that: A majority of the respondents (graduates and students) rated the overall importance, effectiveness and quality of the teacher education programs as important, effective and good. Generally speaking there were only a few significant differences between the cohorts and groups related to the background variables (gender, age). The different cohorts were rating the quality of the programs very similarly but some differences between the cohorts were found in the importance and effectiveness ratings. Graduates of 2001 and 2002 rated the importance of the program significantly higher than 2000 graduates. The effectiveness of the programs was rated significantly higher by 2001 and 2003 graduates than other groups. In spite of these individual differences between cohorts there were no linear trends among the year cohorts in any measure. In respondents’ ratings of the effectiveness of teacher education programs there was significant difference between males and females; females rated it higher than males. There were no significant differences between males’ and females’ ratings of the importance and quality of programs. In the ratings there was only one difference between age groups. Older graduates (35 years or older) rated the importance of the teacher training significantly higher that 25-35 years old graduates. In graduates’ ratings there were positive but relatively low correlations between all variables related to importance, effectiveness and quality of Teacher Education Programs. Generally speaking students’ ratings about importance, effectiveness and quality of teacher education program were very positive. There was only one significant difference related to the background variables. Females rated higher the effectiveness of the program. The comparison of students’ and graduates’ perception about importance, effectiveness, and quality of teacher education programs showed that there were no significant differences between graduates and students in the overall ratings. However there were differences in some individual variables. Students rated higher in importance of “Continuous Professional Development”, effectiveness of “Critical Thinking Skills” and “Using Educational Technology” and quality of “Advice received from the advisor”. Graduates rated higher in importance of “Knowledge of Learning Environment” and effectiveness of “Continuous Professional Development”. According to the qualitative data of study 2 some graduates expressed that their perceptions have not changed about the importance, effectiveness, and quality of training that they received during their study time. They pointed out that teacher education programs have provided them the basic theoretical/formal knowledge and some training of practical routines. However, a majority of the teachers seems to have somewhat critical opinions about the teacher education. These teachers were not satisfied with teacher education programs because they argued that the programs failed to meet their practical demands in different everyday situations of the classroom e.g. in coping with students’ learning difficulties, multiprofessional communication with parents and other professional groups (psychologists and social workers), and classroom management problems. Participants also emphasized more practice oriented knowledge of subject matter, evaluation methods and teachers’ rights and responsibilities. Therefore, they (54.1% of participants) suggested that teacher education departments should provide more practice-based courses and programs as well as closer collaboration between regular schools and teacher education departments in order to fill gap between theory and practice.

Color ad spectral image assessment using novel quality and fidelity techniques

The ongoing development of the digital media has brought a new set of challenges with it. As images containing more than three wavelength bands, often called spectral images, are becoming a more integral part of everyday life, problems in the quality of the RGB reproduction from the spectral images have turned into an important area of research. The notion of image quality is often thought to comprise two distinctive areas – image quality itself and image fidelity, both dealing with similar questions, image quality being the degree of excellence of the image, and image fidelity the measure of the match of the image under study to the original. In this thesis, both image fidelity and image quality are considered, with an emphasis on the influence of color and spectral image features on both. There are very few works dedicated to the quality and fidelity of spectral images. Several novel image fidelity measures were developed in this study, which include kernel similarity measures and 3D-SSIM (structural similarity index). The kernel measures incorporate the polynomial, Gaussian radial basis function (RBF) and sigmoid kernels. The 3D-SSIM is an extension of a traditional gray-scale SSIM measure developed to incorporate spectral data. The novel image quality model presented in this study is based on the assumption that the statistical parameters of the spectra of an image influence the overall appearance. The spectral image quality model comprises three parameters of quality: colorfulness, vividness and naturalness. The quality prediction is done by modeling the preference function expressed in JNDs (just noticeable difference). Both image fidelity measures and the image quality model have proven to be effective in the respective experiments.