Cataloguing Portuguese Tile Patterns

    Starting date: 2010
    Ending date: ongoing

    The project aims to provide the scientific community and the relevant institutions with a catalogue of patterns (and frames) that will help control and standardize the terminology currently used in this field. This resource will be made available on Az Infinitum, in the section on patterns and frames. 

    This is a multidisciplinary project aimed at producing groundbreaking research on patterned azulejos – the most common type of azulejos, and the one that is most prone to disappearing, through theft, trafficking and vandalism. Grounded in the field of Art History, the project combines traditional research methods with knowledge from other scientific areas (mathematics, colour studies, conservation and restoration) and with the most recent and sophisticated forms of computer analysis. This will lay the foundation for new approaches to the study of patterned azulejos, which will end up transcending the scope of the project. The free availability of the data will enable a significant expansion of the results, with a direct impact on Art History, but also on conservation policies, cultural tourism and the business sector. By unlocking the past and the present, the project will have significant implications for the future.    

    While figurative tile decorations have unique (or almost unique) features and are designed for a specific location, patterned azulejos are serially produced and can be applied in any location and combined in different ways. Therefore, the study of these decorations poses specific challenges to art historians, such as the quantification of the high and hitherto undetermined number of patterns that exist in Portugal.  

    The project’s main concept consists in the creation of a specific profile for each pattern, by cross-referencing a series of textual and visual markers. These profiles, organized within Az Infinitum – Azulejo Indexation and Referencing System, are complemented by an automatic image recognition tool, which will enable the identification and comparison of azulejos with each other and with the sources of inspiration used by artists and factories. Once each profile has been created, it will be possible to retrace the life path of a given pattern, wherever and whenever it was applied. This systematic approach may lead, in the near future, to important contributions and new analytical possibilities regarding manufacture and application timelines, colour schemes, authorships, geographic profiles, etc.     

    The project’s team started by cataloguing 18th century patterns, building on the work carried out by Santos Simões (in Azulejaria em Portugal no século XVII, Vol. I – Tipologia, Vol. II – Elenco. Lisbon: FCG, 1971), and is currently focused on azulejos from the late Medieval period, the Pombaline period and the 19th and 20th centuries. 



    1) Create profiles for the patterns (produced or applied in Portugal), based on solid research findings;

    2) Compare patterns with each other and with other sources of inspiration, creating a worldwide visual network (by highlighting the national characteristics of different patterns, it will be possible to situate them within an international context);

    3) Map patterned tiles across the country;

    4) Use this systematization to obtain mensurable data, and thereby provide future answers to questions that, due to the complexity and volume of the data, have hitherto remained unanswered: Which patterns were most frequent in Portugal in a specific period? What is their geographic distribution? Which workshops and factories were most influential? Which sources of inspiration were most used? What was the area of influence of the workshops/factories (at a regional/national level)? How international were the factories and how up-to-date were they with regard to the models produced in Europe at the time?



    The idea of setting up an application for the automatic recognition of patterns is an old one, but it became more pressing with the growing number of catalogued patterns, which made it increasingly difficult to compare them using only human means. 

    After several attempts involving different research groups working on Computer Vision, what started out as a remote wish finally took shape thanks to the application ZULEJO, developed by Catarina Pinheiro, Mathilda Larsson Coutinho (Hercules laboratory, University of Évora) and David G. Ortega (Pomika).

    Using Az Infinitum’s catalogue, ZULEJO allows users to identify patterns and access their catalogue entries. However, its goals are much wider: as part of the field of citizen science, it aims to involve in the cataloguing of Portuguese tiles all of those wishing to contribute to the preservation and promotion of this art form. Apart from providing direct information, ZULEJO may also come to provide custom-tailored information on stores selling tile reproductions, workshops, courses or bookshops, as well as information on museums and monuments containing azulejos. The goal is to create a virtual network focused on Portuguese tiles, to complement the one already in existence. For now, however, ZULEJO is confined to a trial version. 

    Az Infinitum uses VISE (VGG Image Search Engine), a free and open-source software designed to enable visual searches of large collections of images using a specific region of an image as the search query. VISE is developed and maintained by the Visual Geometry Group (VGG), at the Department of Engineering Science of the University of Oxford. Based on Relja Arandjelovic’s DPhil / Postdoc on VGG (2014), VISE is currently developed by Abhishek Dutta, under the coordination of Andrew Zisserman. Az acknowledges the unconditional support received during all the implementation stages and highlights the collaboration of Giles Bergel, VGG’s ambassador, whose help has been invaluable since 2017.   


    The project is developed in partnership with the National Azulejo Museum and will enlist specialists in different topics whenever necessary. 


    Az – Azulejo Research Network:
    Rosário Salema de Carvalho (PI)
    Ana Almeida
    Ana Venâncio (2014)
    Inês Leitão
    Isabel Pires (until 2013)
    Lúcia Marinho (until 2014)
    Patrícia Nóbrega

    National Azulejo Museum:
    Alexandre Pais (co-PI)
    Inês Aguiar (until 2018)

    Sistemas do Futuro, Lda.

    Access the data uploaded to  Az Infinitum – Azulejo Referencing and Indexation System


    Books and book chapters
    SILVA, Libório Manuel – I Love Braga - Janelas, Batentes e Azulejos. Vila Nova de Famalicão: Centro Atlântico, 2015.

    CARVALHO, Rosário Salema de; AGUIAR, Inês – A azulejaria da Igreja vista pelas estudiosas: Doutoras Maria do Rosário Salema e Inês Aguiar. In VAZ, Carlos Nuno – A Igreja de Nossa Senhora-a-Branca. Braga: Irmandade de Nossa Senhora-a-Branca, 2017. p. 459-469.

    Journal articles
    CARVALHO, Rosário Salema de; PAIS, Alexandre; ALMEIDA, Ana; AGUIAR, Inês; PIRES, Isabel; MARINHO, Lúcia; NÓBREGA, Patrícia – 17th century patterned azulejos from the Monastery of Santa Marta, in Lisbon. Journal of Science and Technology of the Arts. 4, 1 (2012): 49-59. Doi:10.7559/citarj.v4i1.66.

    CARVALHO, Rosário Salema de; PAIS, Alexandre; ALMEIDA, Ana; AGUIAR, Inês; PIRES, Isabel; MARINHO, Lúcia; NÓBREGA, Patrícia – 17th Patterned Azulejos from Portugal". Glazed Expressions - The Magazine of TACS, the Tiles and Architectural Ceramics Society. 70 (2012): 16-18.

    CARVALHO, Rosário Salema de; QUEIROZ, Francisco; PAIS, Alexandre; ALMEIDA, Ana; AGUIAR, Inês; PIRES, Isabel; MARINHO, Lúcia; NÓBREGA, Patrícia – Do azulejo manual ao azulejo industrial: a presença da padronagem portuguesa tradicional na produção da Fábrica do Carvalhinho. Cadernos de História da Arte, 1 (2013): 136-155.

    PAIS, Alexandre; CARVALHO, Rosário Salema de; ALMEIDA, Ana; AGUIAR, Inês; PIRES, Isabel; MARINHO, Lúcia; NÓBREGA, Patrícia – Azulejos de padrão - uma proposta de catalogação. INVENIRE - Revista de Bens Culturais da Igreja. 3 (2011): 12-15.

    Conference proceedings
    AGUIAR, Inês; CARVALHO, Rosario Salema de Carvalho – Az Infinitum. Azulejo Indexation and Referencing System. IV Encuentro Internacional de Historia del Arte y Cultura Artística Digital: Digital Art History and Artistic Culture. IV International Meeting, 47-49. Málaga: University of Málaga Art History Department, 2016. Available at

    CARVALHO, Rosário Salema de – Cataloguing Baroque azulejo frames. A project in progress. AzLab#14 Azulejos and Frames. Proceedings (special issue of ARTisON), 2 (2016): 33-41. Available at

    MACHADO, Ana Raquel; CARVALHO, Rosário Salema de – Frame simulations in 18th century azulejos. AzLab#14 Azulejos and Frames. Proceedings (special issue of ARTisON), 2 (2016): 42-53. Available at

    QUEIROZ, Francisco; AGUIAR, Inês; CARVALHO, Rosário Salema de; PIRES, Isabel – Azulejaria e Arquitectura Vernacular: os padrões usados no Concelho de Ovar e o Sistema 'Az Infinitum'.  Actas do 1o Colóquio Internacional Arquitectura Popular. Arcos de Valdevez: Município de Arcos de Valdevez, 2016. p. 913-926. Available at

    CARVALHO, Rosário Salema de – Baroque azulejo's frame". Framings. Berlin: Logos Verlag Berlin GmbH, 2015. p. 193-210.

    CARVALHO, Rosário Salema de, Alexandre Pais; FORMIGA, Porfiria – Azulejos e emolduramentos: um puzzle com solução à vista = Azulejos and frames: a puzzle with a solution in sight. In SEMEDO, Alice; SENRA, Sandra; AZEVEDO, Teresa – Processos de Musealização. Um Seminário de Investigação Internacional. Atas do Seminário = Musealisation Processes. An International Research Seminar Conference Proceedings [em linha]. Porto: Universidade do Porto, Faculdade de Letras, Departamento de Ciências e Técnicas do Património, 2015. p. 184–201. Available at

    CARVALHO, Rosário Salema de – As guarnições como elementos estruturadores da narrativa azulejar. In Ciclos de Iconografia Cristã na Azulejaria. Actas do I Colóquio Sacrae Imagines. Lisboa: Secretariado Nacional para os Bens Culturais da Igreja, 2013. p. 45–61.

    Oral presentations
    CARVALHO, Rosário Salema de – "Az Infinitum – Sistema de Referência & Indexação de Azulejo". 9o Encontro Tecnologias Aplicadas ao Patrimônio, Auditório – Secretaria de Estado da Cultura de São Paulo, 19 May 2016.

    _____ – I Love Braga. I Love Braga - Janelas, Batentes e Azulejos, Museu D. Diogo de Sousa (Braga), 14 November 2015.

    CARVALHO, Rosário Salema de; AGUIAR,Inês – Azulejos & Molduras. Workshop Semana da Ciência e a Tecnologia 2015, Faculdade de Letras, Universidade de Lisboa, 27 November 2015.

    AGUIAR, Inês – A Fotografia e a imagem digital no desenvolvimento do conhecimento –  o projecto Az Infinitum. Presentation [by invitation] at AzLab #15: A Fotografia como Documento, Faculdade de Letras da Universidade de Lisboa, 17 July 2015.

    _____ – Reframing: Cataloguing Patterned Azulejo Frames. Presentation [with scientific refereeing] at AzLab#14 Azulejos and Frames, Faculdade de Letras da Universidade de Lisboa, 21 May 2015.

    CARVALHO, Rosário Salema de, Alexandre Pais; FORMIGA, Porfiria – Azulejos e emolduramentos: um puzzle com solução à vista. Presentation [with scientific refereeing] at Processos de Musealização. Um Seminário de Investigação Internacional, Faculdade de Letras da Universidade do Porto, 6 November 2014.

    CARVALHO, Rosário Salema de, Alexandre Pais – Azulejos pombalinos. A memória de um estadista incómodo. Presentation [by invitation] at Jornadas SIPA 2013: A Experiência Documental em Arquitetura e Urbanismo, Faculdade de Letras da Universidade de Lisboa, 10 Ocotber 2013.

    CARVALHO, Rosário Salema de – Imagens e padrões em inventários de azulejos: Projectos interdisciplinares na área da azulejaria. Presentation [by invitation] at Seminário Estudos de Caso de Cultura Material, Museu Nacional de História Natural e da Ciência (Lisboa), 21 September 2010.

    _____ – The Frames of Portuguese Baroque Azulejos. Presentation [with scientific refereeing] at​​​​​ Jeux et enjeux du cadre dans les systèmes décoratifs à l'époque moderne, Institut national d’histoire de l'art (Paris), 10 May 2014.

    QUEIROZ, Francisco – Azulejaria e Arquitectura Vernacular: os padrões usados no Concelho de Ovar e o Sistema "Az Infinitum". Presentation [with scientific refereeing] at​​​​​ Colóquio Internacional Arquitectura Popular. Conceitos e expressões. Valores culturais, sociais e económicos, Arcos de Valdevez, 3 April 2013.