Librarian cornered by images or How to index visual resources
Wanda Klenczon, Paweł Rygiel
Wanda Klenczon, librarian at the National Library of Poland (1987- ), Head of Bibliographic
Institute (2007- ), chair of Technical Committee Information and Documentation of Polish
Standardization Committee. Responsible for the development of bibliographic standards
used in the Polish National Bibliography, authority control and subject indexing (National
Library of Poland Subject Headings, UDC).
Paweł Rygiel, librarian at the National Library of Poland since 2008. Interested in image
indexing and retrieval.
Abstract
Presenting museum, library and archive collections online has become a common practice in
recent years. Among the data accessible via the Internet are visual resources such as
paintings, drawings, engravings and photographs, which constitute a rich and vital source of
information. Image indexing is an extremely difficult task. The crucial question is: how to
transform the visual code of an image into written code. This paper presents standards of
still images description, guidelines and indexation tools, advantages and disadvantages of
their usage, their potential to provide authoritative and comprehensive access points to
digitized resources and to support sophisticated search. In order to provide efficient access
to the digitalized images presented at the National Digital Library Polona and to promote
their re-use, we are looking for a model of images subject indexing.
Introduction
Digital technologies and the online presentation of digital images collections by libraries,
museums and archives have enabled wide, absolutely democratic access to resources that
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were previously available only for researchers. Among the data accessible via the Internet
are visual resources such as paintings, drawings, engravings and photographs, which
constitute a rich and vital source of information about art, but also about history of people
and places, culture and tradition, social life, interests and customs… “While some image
collections may be of interest only to researchers in a narrow field […], other image
collections are being created that will be of interest to many, including the artist, the
scientist, the educator, the historian, the journalist, the student, and the leisure seeker”
(Jörgensen, 2003, p. 1).
Availability of both digitalized images and their descriptions has placed them in a new
context, while the ways of searching for information have also evolved (Jörgensen, 2003;
Jansen, 2008). Moreover, descriptions have been subject to assessment and verification by
users who access the freed resources. Collections and institutions may take advantage of
this situation as it positively affects the quality of descriptions and helps complete the
missing data (see Springer et al., 2008).
Digitalization of images requires a lot of time, money and effort. An extremely difficult task
that the cultural heritage institutions have to undertake is to assign high quality semantic
metadata to the non-textual materials. Although the automatic recognition of images seems
to be a very promising perspective, there are layers of meaning that can be indexed only by
using human knowledge, experience and intuition. “Properties of an image such as shape,
texture, and color contribute to our understanding of an image, but do not define it. Textbased search techniques remain the most efficient and accurate methods for image
retrieval”. (Jörgensen 1999, 302; Neugebauer 2005).
The National Library of Poland as the central library of the state and one of the most
important cultural institutions in Poland is responsible for the preservation and promotion of
the Polish cultural heritage. The National Digital Library Polona1 is the repository and the
platform for enhancing access to the NL’s digital collections. The number of images (such as
prints, drawings, photographs, postcards, posters, bookplates) among the digitized
documents constantly increases. In order to provide efficient access to the digitalized images
and to promote their re-use, a model of cataloguing and subject indexing should be
1
http://www.polona.pl
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established. The main goal is to enhance access to both general and specific depicted
objects, regardless of the knowledge level of users and their information competency. And
last but not least, our intention is to achieve semantic interoperability between the various
data and subject schemes used in the Polish libraries and museums communities. In this
perspective a few questions should be answered: what vocabulary should be used? What
description level would be useful? How could research results be maximized?
Image indexing and retrieval – rules, tools and questions
Subject indexing consists of the following sequence of steps: subject analysis, selection of
information and its translation into the language of indexing i.e. transforming the message
by changing its language without the loss of information, as far as possible (Chu & O’Brien,
1993; Lancaster, 1998). In the case of iconographic documents it also involves transforming
visual code into written code, visual information into textual description, and “the process of
translating the content of an image into verbal expressions poses significant challenges to
concept-based indexing“(Matusiak, p. 285).
The subject analysis of a language resource can be defined as a process of establishing the
subjects of a document. During the process of subject analysis the most suitable subject
headings (or descriptors) for the comprehensive description of its content are found. Such
analysis is not an easy task. The question is which features of documents should be
considered in the subject analysis? (Albrechtsen, 1993). Visual materials may require a
completely different approach. Certain features, like title, author, appearance, can be easily
identified and used in the description as access points. Furthermore, any image can be
differently perceived and interpreted by various groups of users, who may have varying
competencies and specific needs.
First of all, in thinking about image indexing, it is necessary to ask if the description of the
subject and content of an iconographic document is at all possible. If so, how should it be
described? What is the subject of such a document? What is it about? How should works of
art be interpreted and what should be included in their description? What aspects of images
may be interesting to users?
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The problem of analyzing the meaning of a work of art has been discussed by the art
historian, Erwin Panofsky, who defined three levels at which a work of art could be
described. He suggested that there might be three strata of the meaning of an art work. A
work of art can be described on the pre-iconographic level, which consists of general aspects
– the primary or natural subject matter; the iconographic level, which encompasses concrete
aspects – the secondary or conventional subject matter; and the iconological level, which
includes symbolic, abstract aspects – the intrinsic meaning or content (Panofsky, 1962).
These three strata of interpretation (pre-iconographic description, iconographic analysis and
iconological interpretation) require specific skills from the interpreter, namely practical
experience, the knowledge of resources, themes and concepts as well as synthetic intuition
(Panofsky, 1962).
Panofsky’s scheme was enriched by Sara Shatford, who also adapted her ideas to image
indexing (Shatford, 1986). She renamed Panofsky’s strata as generic, specific and abstract
and subdivided each of these areas into four aspects, each of which forms an answer to one
of the following questions: Who?, What?, Where?, When?. In this way she created a model
of description that encompasses all the aspects of a picture. According to the
Panofsky/Shatford model, there are three levels of analysis and description:
-pre-iconographical (generic things, such as woman, flower, building),
-iconographical (specific things, such as Salome, rose, temple), and
- iconological (symbolic or abstract things, such as heaven, love, New Jerusalem).
For example, a flower may be depicted as an element of inanimate nature, simply for its
beauty, and it may also appear as a symbol or an element of an iconographical program.
Shatford also introduced the distinction between OF (what a picture consists of) and ABOUT
(what a picture is about). The OF/ABOUT paradigm was a critical change that Shatford made
to Panofsky’s theories, bringing iconography out of the realm of Renaissance art and into the
broader realm of images in general.
The process of indexing is connected with the concepts of ofness and aboutness and isness.
Aboutness is the more widely used one of the two terms. It focuses on what is conveyed in a
document, what it is about, what its content, subject or theme is. Aboutness depends on the
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interpretation of the set themes, motifs, actions and events in a work. It is one of the many
terms used for expressing certain features of a text or document (features different from the
form and the so called description data). Aboutness (and other terms with the same
meaning), as a vital element of the organization of knowledge and information retrieval, has
been discussed by many researchers (see Hjørland, 2001).
Aboutness is a category that can be used for both language and non-language resources,
while the other category – ofness – is a term which only applies to the analysis of pictures.
Ofness refers to the elements that a picture consists of. The concepts of aboutness and
ofness used in picture description are based on Panofsky’s theory about the three strata of
meaning in a work of art. Aboutness and ofness are characteristic of the pre-iconographic
and iconographic levels of description. Panofsky’s third stratum – the iconological level of
description – refers to the interpretation of the inner meaning or content of a work of art
(Panofsky, 1962; Shatford, 1986; see also Zeng, Žumer, & Salaba, 2010).
Isness is another concept which appears in the process of indexing. It tells us what the
resource is. Very often this element is close to genre/form terms. The isness of a resource
can be physical or intrinsic, e. g. textbook, DVD, poetry, libretto, etc. (Ingwersen, 2002).
Core principles for describing and indexing images have been discussed and agreed upon at
the international level by art historians and information professionals (with the predominant
role of American experts). The fundamental set of rules and recommendations in this area is
known as CCO, Cataloging Cultural Objects. A Guide to Describing Cultural Works and Their
Images (Baca et al. 2006). It enumerates the mandatory elements of description, such as:
1. Object Naming,
2. Creator Information,
3. Physical Characteristic,
4. Stylistic, Cultural and Chronological Information,
5. Location and Geography,
6. Subject,
7. Class,
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8. Description.
This is a general frame, the basic standard of data content, but the choice of appropriate
indexing tool and the decision about indexing policy must be taken by each cataloguing
agency respectively according to its collection profile and its users’ needs.
There are two crucial questions to be answered while deciding about images indexing:
- what level of description should be adapted? What is our intention: to express
what the image represents (the OF aspect in both a specific and generic sense), or
what the image is about (the ABOUT aspect), or to index both of them?
- what indexing tool (tools) could be used successfully? Controlled or uncontrolled
vocabulary or both of them? Internationally approved thesaurus or local information
language?
While creating an image description, the cataloguer may consider the formal aspects of the
object (such as the medium, the technique and/or the material) and other categories that
are not directly related to the content of an image. These may include:
-
type of document/field of art (photography, engraving, drawing, painting)
-
technique/material (collage, oil on canvas, woodcut, ivory carving, photogravure)
-
dating (17 century, 1201-1300, the end of 15 century)
-
culture, epoch, art movement (Dutch art, Ming Dynasty painting, Art Deco)
However, the indexer’s main task is to specify content features and to create the description
of the “content” of a document. The basic elements of content include, among others:
-
objects and actions (a girl, a cottage, a boat, a meadow, a bird, sowing)
-
type of picture (sketch, self-portrait, still life, veduta, seascape)
-
scene or iconographic type (Adam and Eve, Madonna Lactans, Last Supper, Cupid and
Psyche, Buddha Amitabha).
Subject analysis and the description of “content” of iconographic documents are sources of
numerous problems (Svenonius, 1994; Roberts, 2001). Establishing and defining the subject
and meaning of an image may be problematic and identifying the objects is often difficult.
Furthermore, the indexing of multifaceted, often allegoric or symbolic images, which are
interpreted on many different levels, presumes a certain degree of knowledge of
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iconography (Schroeder, 1998; Jacobs, 1999). Abstract images, images related to a foreign
culture, and images created in different epochs each may contain elements of unknown
meaning, indecipherable symbols and gestures, are another source of problems. Finally, the
circumstances in which the work was created (usually only known to the author of the work)
may influence the interpretation of an image. The most difficult and problematic task is to
express the highest level of meaning, which is the third level of Panofsky/Shatford model:
iconology/interpretation. Only specialists or very experienced indexers will recognize some
signs and symbols and, by reading between the lines, reconstruct the highly sophisticated
iconographical program, e.g. “an image of a grey brick wall is about socialism” (Neugebauer,
2005, p.5). As Herbert Read noted “What we really expect in a work of art is a certain
personal element – we expect artist to have, if not a distinguished mind, at least a
distinguished sensibility. We expect him to reveal something to us that is original – a unique
and private vision of the world.” (Read, 1968, p. 27) Unfortunately, very often we are unable
to name and express what is important, unique and original in this vision, its sense remaining
inaccessible or unexpressed.
In addition to the general problems with indexing of images, there are some questions
connected with the rules governing the creation of the authorized access points and with the
usage of the subject authority file. In this context a few specific problems can be
enumerated:
-
usage of detailed description vs. assignment of broader concepts,
-
relation with authority file and with general indexing policy - consistency or
independence?
-
descriptive cataloguing and subject indexing – complementarity or independence?
Detailed description vs. broader concepts
It is obvious that the first and second level of images content should be indexed, but each
cataloguing institution has to make a choice between assignments of strictly adequate or
broader concepts. It is a crucial decision and not an easy one.
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For example, Caravaggio’s Basket of Fruits may be indexed using single term referring to the
art genre – “Still life”. For advanced iconographic researches, a detailed description (“apple;
fig; grape; pear; basket”) could be more useful. A print which presents over twenty portraits
of famous Italian singers may be indexed with subject heading “Singers” (with geographical
subdivision “-Italy”) and general subject designation “Portrait”. Is it enough? The other
option is to enumerate, as additional subject access points, all the names of the fifty
depicted person: “Agujari, Lucrezia (ca 1743-1783); Amicis, Anna Lucia de (ca 1733-1816);
Amorevoli, Angel (1716-1798); Ansani, Giovanni (1750-1815)” etc. Which of these solutions
is better? Which of them could satisfy the need of various audiences and maximize research
results?
Assignment of broader concepts facilitates the indexing – it is easier and less timeconsuming and the information about described objects is not dispersed. On the other hand,
in order to give the users the complete iconographic information and comparative material
for studies, all objects identified in the picture should be accepted as subject access points.
Another important question which should be answered before making decisions is: “Will
your system link a specific term to its broader contexts and synonyms in an authority file? If
not, you should include important broader contexts and synonyms in the work record.”
(Baca et al. 2006)
Relation with authority file and with general indexing policy - consistency or flexibility?
If the cataloguing institution provides authority control, the main problems are how the
detailed terms describing images could be integrated into an indexing system exploring a
local subject authority file and how to ensure consistency in indexing policy. For example, NL
of Poland has been using, for more than thirty years, its own indexing tool – JHP BN
(National Library of Poland Subject Headings). All collections are indexed using this
controlled vocabulary and according to the general indexing guidelines. The indexing
language is able to provide many generic terms, but for detailed descriptions of images the
subject authority file should be extended by thousands of terms corresponding to types of
objects and architecture, materials, types of people and activities, physical attributes,
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associated concepts etc. Most of these specific terms could occur only in the images
description.
Problems with image indexing are clearly evident also in the case of architectural objects or
persons, for which names usually come from the authority file. One should ask, however, if
all the aspects of iconographic material have been considered and whether current solutions
are adequate for the description of images and suited to the expectations of users. One of
the most serious problems in identification is determining what the image presents and
when the image was created (who owned the object at that time, what the object looked
like, what its function was). There is also the question of what version of the name to choose
– e.g. the name in the language of the country in which the object is currently located or the
name the object had at the time the image was created? It is also necessary to decide
whether to make the heading appropriate for the image (refer to the time when the image
was created and the name that the object then had) or to use the latest (current) name of
the object with a suitable chronological subdivision. This is connected with the rules of using
proper names of objects within the file and the way such names function in the catalogue –
should headings be appropriate for objects or should one name be selected and used
consistently although it may not be suitable for all the different images of the object? This
has significant influence on the process of searching for information in the catalogue. If the
heading appropriate for the object is used, users are more likely to find exactly what they
are searching for, but the entire context is lost, information is dissociated from the object,
and the material becomes more difficult to find. Adoption of the latter solution, however,
will lead to creating inadequate descriptions, while the material is overly concentrated. A
similar problem refers to personal names: whether the heading in the authority file refers to
the latest name used by a person or to the most frequently used name. A print representing
the king of Poland Henryk Walezy and his court would be indexed with the name “Henry III
(king of France)”, which was his latest and most frequently used name, preferred in the
authority file.
Descriptive cataloguing and subject indexing – complementarity or independence?
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There are elements of subject description that sometimes appear as an element of
descriptive cataloguing (like title, date, type of representation stated in the title). Some titles
include exact information about the content. For example: “White roses, chrysanthemums in
a vase, peaches and grapes with a white tablecloth” painted by H. Fantin-Latour (1876).
Should this information be repeated as subject terms? The CCO rules state that “if terms
repeat or overlap terms applied to other elements such as Title or Work Type, a thorough
description and indexing of the subject content should be done separately in the Subject
element.” The cataloguing institution, taking into account the technical aspects of searching
and retrieval, should consider the pros and cons and make its own decision regarding
cataloguing policy.
The popular method of image indexing is to provide the basic bibliographic data, such as
name of creator, title, date, material, measure, and to support the image with some
descriptive text (Neugebauer, 2005). It is the current practice of several museums showing
their collections both in traditional publications and accessible on a Web site. In the libraries
communities, however, the tradition of indexing based on controlled vocabularies organized
in authority files is stronger.
There is no vocabulary standard that would satisfy the needs of all cultural heritage
institutions. Regarding subject indexing of images, several tools and methods may be taken
into account:
- controlled vocabulary (thesauri, subject headings, or classifications) – terms
expressing both depicted objects and form/genre/type of document taken from an
authority file may be used as elements of pre-coordinated strings (according to local
indexing rules) or as single subject access points
Libraries do not use all the existing indexing tools for the description of iconographic
documents. Some of the tools (such as subject headings) are too general to enable the
description of certain elements of the iconographic aspect of images; others, such as the
Library of Congress Thesaurus for Graphic Materials (TGM), the Art & Architecture Thesaurus
(AAT), and Iconclass, encompass elements connected with both the technique of creation
and the iconography of objects (Baca 2002; Harpring 2010).
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Numerous libraries have indexed their images collection using thesauri and subject headings.
The great picture collections of the Library of Congress are indexed using several indexing
tools: Library of Congress Subject Headings and terms derived from specialized thesauri such
as TGM and AAT. This practice confirms that even the most detailed vocabulary of subject
headings is inadequate to index the extensive semantic layers of images or issues related to
the formal aspect of the work.
Similarly, for indexing collections of images the Bibliothèque nationale de France use its
subject headings language RAMEAU to a very limited extent. The headings are completed
with keywords taken from thesauri or lists dedicated to this type of collection.
- uncontrolled vocabulary – keyword created by indexers without semantic control
or tags (folksonomy) created both by the inexperienced users and experts
Keyword indexing is not very popular in the libraries, and also museums seem not to be
interested in practicing free keywords assignment. There are, however, some projects in the
museums community exploring the advantages of social tagging in indexing work of art and
artifacts. The best known among them is “Steve. The Museum Social Tagging Project”: tags
assigned by digital museum visitors have completed museums’ formal descriptions of works,
created by art historians or other specialists. There is no limit to the number of terms that
may be assigned per image; some of the presented works are tagged with more than fifty
tags. “Steve project” shows all the disadvantages of social tagging: redundancy in terms,
inconsistency of spelling, inappropriate, meaningless and subjective expressions. There are,
nevertheless, a lot of additional access points which are relevant and constitute added value
in images retrieval.
- notes containing the free-text description of the image, additional data about it and
scientific commentary – created by indexers
This solution is hardly used in the libraries but well-liked by art historians which have no
experience (or very little experience) with controlled vocabulary systems.
When analyzing a variety of principles, rules and tools, one sentence comes to mind: “A
picture is worth a thousand words”. It is the statement that may frustrate all librarians
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looking for an effective model for images indexing. It is also the great challenge we have to
undertake.
Instead of the conclusion: a modest proposal
Looking for a model of image description, we analyzed several standards and practices of
some large libraries and museums. CCO is the most complex and appreciated among data
content standards. Our intention is to respect these guidelines as much as possible.
Nevertheless, it must be taken into account that images are a minor part of the NL’s
collection and must be recorded and indexed consistently with common cataloguing rules.
All digitized images available at the National Digital Library Polona are primarily described in
the NL’s OPAC and the bibliographic record created in MARC21 format is linked to the
metadata record in the Dublin Core scheme used in the digital library. Subject terms
dedicated to images indexing must be stored in the common subject authority file. The local
indexing language JHP BN (National Library of Poland Subject Headings) is used as our
standard for subject data value and the use of terms from other vocabularies is excluded.
When indexing images we intend to exploit JHP BN controlled vocabulary as subject terms,
genre/form term or keywords, recorded in several MARC21 fields:
600-651 subject terms (controlled vocabulary)
Terms should be specific to the overall scope of the document (what the image is “of”),
including names of persons and corporate bodies, names of places, events, objects. Each real
object and each scene or iconographic type, if identified, should be indexed. Generic and
specific things which are the basic elements of the content should also be enumerated.
Secondary elements may be captured as additional subject access points.
If the content is multi-layered or not consistent, only a genre/form term is assigned.
655 genre/form term (controlled vocabulary)
Terms should express the type of document (e.g. painting, drawing, photography, print),
technique (e.g. etching, watercolor, gouache, albumen print) and object genre (e.g. portrait,
landscape, seascape, city view, genre scene, mythological scene, allegory).
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653 additional subject access points (both controlled and uncontrolled terms)
Terms related to secondary, subordinated or less important content elements, e.g. objects
depicted in the background and as staffage. It is also possible to give a broader context and
synonyms of specific terms used both as subject and genre/form terms.
and 520 note/summary, that may contain free-text description, including the meaning,
purpose or function of image (what the picture is “about”). It may also include information
about the style or period, material, form and composition etc.
The proposal will be discussed with the Polish professionals responsible for images
cataloguing and indexing and with the art historian community. In our opinion, the scheme
presented above is acceptable for both library and museum experts. It is partly analogous to
the concept of description implemented in the first Polish digital museum2. A consistent
documentation of objects collected in cultural heritage institutions would make the
resources of images more accessible and would serve successfully as a basis for scientific
research and education.
2
http://cyfrowe.mnw.art.pl
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Examples
(For make examples more comprehensible English equivalents of JHP BN subject terms are
given)
Example nr 1.
100 1 Hiszpański, Stanisław |d(1904-1975).
245 10 Odwieziony we śnie na Itakę |h[Dokument ikonograficzny].
246 13 |iZnane także jako:|aOdyseusz repatriowany
260 |c1964.
300 1 rys. :|btusz-pędzel, akwar., na szkicu ołówkowym ;|c32,5x23 cm.
520 Odysseus, fast asleep in a hidden harbor on
Ithaka. Athena is keeping vigil over him. In
background the sea and an ship, probably
Phaeacian.
600 Odysseus
653 Homerus. Odusseia; Athena; Ithaka; sea;
ship; harbor; man asleep; Greek mythology;
Greek goddess; gorgoneion
655 Illustration
655 Watercolour
655 Coloured drawing
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Example nr 2.
100 1 Adam, Jean Victor|d(1801-1866).
245 10 Haquet et traîneau de brasseur|h[Dokument ikonograficzny]
/|cV. Adam del.
260 [À Paris] :|bLith. de C. Motte,|c[1830].
300 1 graf. :|blitogr. ;|ckompoz. 12,4x20,5 cm, z napisami 16x22 cm.
520 This print is probably a part of a larger series entitled 'Voitures'. At center of
composition, a brewer's dray and sledge loaded with barrels; at right, in front of a café with
an awning, a man on horseback
and a man holding a barrel; beyond
at left, buildings and a small crowd
of soldiers;
653 road; horses; coffeehouse;
barrel; delivery; awning; carriage
655 Genre scene
655 Lithograph
655 Print
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Example nr 3.
100 1 Drzewiecka, Helena.
245 10 [Bukiet kwiatów]|h[Dokument ikonograficzny].
260 |c[1815-1820].
300 1 rys. :|bgwasz, pap. brązowy ;|c33,6x25,6 cm.
650 Flowers
653 pansy; iris; lily; ancolie; rose; bouquet
655 Gouache
655 Painting
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Example nr 4.
100 1 Rzewuski, Walery|d(1837-1888).
245 10 [Helena Modrzejewska jako Małgorzata w spektaklu "Faust"
Johanna Wolfganga Goethego]|h[Dokument ikonograficzny] /
|c[Walery Rzewuski].
260 |c[1869].
300 1 fot. :|bodb. albuminowa ;|c9,1 x 5,5 cm.
520. “Gretchen in the cathedral tormented by an Evil Spirit”
or “Gretchen refuses to escape from prison” (?). Photograph
has been taken in Rzewuski atelier after the spectacle in the
Stary Teatr in Kraków 13 or 14.02.1869
600 Modrzejewska, Helena|d(1840-1909)
653 Goethe, Johann Wolfgang von(1749-1832).Faust;
Actress; Polish theatre; Margaret; Gretchen
655 Photograph
655 Portrait
655 Albumen print
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REFERENCES
Albrechtsen H. (1993). Subject Analysis and Indexing: From Automated Indexing to Domain
Analysis. The Indexer, 18(4), 219–224.
Baca, M. (ed.). (2002). Introduction to Art Image Access: Issues, Tools, Standards, Strategies.
Los Angeles: Getty Research Institute. Retrieved from
http://www.getty.edu/research/publications/electronic_publications/intro_aia/index.html
Baca, M., Harpring, P., Lanzi, E., McRae. L & Whiteside, A. (2006). Cataloging cultural objects:
a guide to describing cultural works and their images. Chicago: American Library Association.
Chu, C. M., & O’Brien, A. (1993). Subject Analysis: The First Critical Stages in Indexing. Journal
of Information Science, 19, 439-454.
Harpring, P. (2010). Introduction to Controlled Vocabulary: Terminology for Art, Architecture
and Other Cultural Works. Los Angeles: J. Paul Getty Trust. Retrieved from
http://www.getty.edu/research/publications/electronic_publications/intro_controlled_voca
b/index.html
Hjørland, B. (2001). Towards a Theory of Aboutness, Subject, Topicality, Theme, Domain,
Field, Content. . . and Relevance. Journal of the American Society for Information Science and
Technology, 52(9), 774–778.
Ingwersen, P. (2002). Cognitive Perspectives of Document Representation. In H. Bruce, R.
Fidel, P. Ingwersen & P. Vakkari (Eds.) Emerging Frameworks and Methods: Proceedings of
the Fourth International Conference on Conceptions of Library and Information Science (CoLIS
4) , pp. (285-301). Greenwood Village, Colo.: Libraries Unlimited.
Jacobs, C. (1999). If a Picture is Worth a Thousand Words, then…. The Indexer, 20(3), 119121.
Jansen, B. J. (2008). Searching for Digital Images on the Web. Journal of Documentation,
64(1), 81-101.
18
Jörgensen, C. (1999). Access to pictorial material: a review of current research and future
prospects. Computer and the Humanities, 33(4), 293-318.
Jörgensen, C. (2003). Image retrieval: theory and research. Lanham, MD & Oxford:
Scarecrow Press.
Lancaster, F. W. (1998). Indexing and Abstracting in Theory and Practice. 2nd ed. London:
Library Association Publishing
Matusiak, K. (2006). Towards User-Centered Indexing in Digital Image Collections. OCLC
Systems and Services, 22(4), 283-298.
Neugebauer, T. (2005). Image Indexing. Photography Media Journal, March. Retrieved from:
http://www.photographymedia.com/article.php?page=1&article=AImageIndexing
Panofsky, E. (1962). Studies in Iconology: Humanistic Themes in the Art of the Renaissance. New
York: Harper & Row. (first ed. New York: Oxford University Press, 1939).
Read, H. (1968). Meaning of Art. London: Faber.
Roberts, H. E. (2001). A Picture Is Worth a Thousand Words: Art Indexing in Electronic
Databases. Journal of the American Society for Information Science and Technology, 52(11),
911-916.
Schroeder, K. A. (1998). Layered indexing of images. The Indexer, 21(1), 11-14.
Shatford, S. (1986). Analyzing the Subject of a Picture: A Theoretical Approach. Cataloging. &
Classification Quarterly, 6(3), 39-62.
Springer, M., Dulabahn, B., Michel, P., Natanson B., Reser D., Woodward D., & Zinkham, H.
(2008). For the Common Good: The Library of Congress Flickr Pilot Project. Retrieved from
http://www.loc.gov/rr/print/flickr_report_final.pdf
Svenonius, E. (1994). Access to nonbook materials: the limits of subject indexing for visual
and aural languages. Journal of the American Society of Information Science, 45(8), 600-606.
19
Zeng, M. L., Žumer, M., & Salaba, A. (Eds.). (2010). Functional Requirements for Subject
Authority Data (FRSAD). A Conceptual Model. München: K. G. Saur.
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