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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Query Construction and Result Presentation based on Graph Codes</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Stefan Wagenpfeil</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Felix Engel</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Paul McKevitt</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Matthias Hemmje</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Academy for International Science</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Research (AISR)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Derry/Londonderry</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Northern Ireland</string-name>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>University of Hagen</institution>
          ,
          <addr-line>Universitätsstrasse 1, D-58097 Hagen</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <fpage>52</fpage>
      <lpage>66</lpage>
      <abstract>
        <p>Indexing and Retrieval of Multimedia is generally implemented by employing feature graphs. These graphs typically contain a significant number of nodes and edges to reflect the level of detail in feature detection. A higher level of detail increases the efectiveness of the results, but also leads to more complex graph structures. However, graph-traversal-based algorithms for similarity are quite ineficient and computation intensive, especially for large data structures. Graph Codes provide a flexible and highly eficient solution to deliver fast and efective retrieval. This significant increase in eficiency and effectiveness, especially for Multimedia indexing and retrieval, is applicable to images, videos, text, and Social Media information features. However, existing query construction methodologies and retrieval algorithms have to be extended to utilize the higher level-of-detail and the fusion of these various Multimedia technologies. Thus, in this paper we present detailed concepts of query construction, retrieval, the corresponding user interfaces, result presentation, and a brief overview of our prototypical implementation based on Graph Codes.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;indexing</kwd>
        <kwd>retrieval</kwd>
        <kwd>multimedia</kwd>
        <kwd>query construction</kwd>
        <kwd>semantic querying</kwd>
        <kwd>graph algorithm</kwd>
        <kwd>graph code</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction and Motivation</title>
      <p>
        Multimedia assets like images, videos, texts, or audio are deeply integrated in today’s life for
many users. The ease of creating Multimedia content e.g., on Smartphones, and publishing it
on Social Media is unseen in history. Infrastructure services like high-speed networks,
cloudservices, or online storage need a good and fast indexing of Multimedia content [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] as e.g.
every single minute, 147.000 photos are uploaded to Facebook, 41.6 million Whatsapp messages
are sent, or 347.000 stories are posted by Instagram [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. Users have thousands of pictures on
their smartphones and ten-thousands on their computers and storage clouds. As typically,
more than one picture is taken from a certain scene, duplicates, similar images, and irrelevant
images become more and more. The same arguments can be applied to video, audio, and text
information, as well.
      </p>
      <p>
        For the users, an easy-to-use and highly flexible querying is required, to distinguish between
relevant and irrelevant pictures and to provide accurate retrieval results. In our previous work
[
        <xref ref-type="bibr" rid="ref3">3</xref>
        ][
        <xref ref-type="bibr" rid="ref4">4</xref>
        ][
        <xref ref-type="bibr" rid="ref5">5</xref>
        ][
        <xref ref-type="bibr" rid="ref6">6</xref>
        ], we already introduced a Generic Multimedia Analysis Framework (GMAF) to fuse
features from diferent Multimedia asset types into a single Multimedia Feature Graph (MMFG)
and a very efective and eficient mathematical processing model based on 2D representations
of the MMFG, called Graph Codes. When employing Graph Codes, comparison algorithms can
be performed with linear complexity (corresponding to the number of nodes and edges), while
graph-based algorithms mostly have exponential runtime. A detailed overview of the evaluation
is given in [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Additionally, Graph Codes provide a much higher level-of-detail.
      </p>
      <p>In this paper, we will define the concepts and modeling for query construction and result
presentation based on Graph Codes. Section 2 summarizes the current state of the art and
related works, section 3 contains the detailed model of query construction algorithms and the
presentation of their results. Additionally, we built a prototypical implementation to illustrate
and refine the concepts. Details of this implementation are given in section 4. Finally, section 5
gives the conclusion and an outlook to future work is given.</p>
    </sec>
    <sec id="sec-2">
      <title>2. State of the Art and Related Work</title>
      <p>This section provides an overview of current Multimedia feature extraction techniques
supporting indexing and retrieval, which either represent or contribute to indexing features of
Multimedia content, which are relevant for querying and result presentation. A brief overview
and summary of the related works, especially the Generic Multimedia Annotation Framework
(GMAF), the Multimedia Feature Graph (MMFG), and the Graph Code concept is given as well.
Finally, in this section we will illustrate current querying and result presentation techniques.</p>
      <p>
        In our previous work, we already introduced the Generic Multimedia Analysis
Framework (GMAF) [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ][
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ][
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] as an unifying framework, that is able to fuse various Multimedia
features into a single datastructure. The GMAF utilizes selected existing technologies as plugins
to support various Multimedia feature detection algorithms for text (e.g. social media posts,
descriptions, tag lines) [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ][
        <xref ref-type="bibr" rid="ref8">8</xref>
        ][
        <xref ref-type="bibr" rid="ref9">9</xref>
        ], images (especially object detection and spatial relationships
including the use of machine learning) [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ][
        <xref ref-type="bibr" rid="ref11">11</xref>
        ][
        <xref ref-type="bibr" rid="ref7">7</xref>
        ][
        <xref ref-type="bibr" rid="ref12">12</xref>
        ][
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], audio (transcribed to text) [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ]
[
        <xref ref-type="bibr" rid="ref11">11</xref>
        ], and video including metadata [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] and detected features [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ][
        <xref ref-type="bibr" rid="ref17">17</xref>
        ][
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>
        The GMAF produces a Multimedia Feature Graph (MMFG), which is defined in [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] and
represents various integrated Multimedia features. Within an application, these MMFGs are
typically represented as a collection. As the fusion of Multimedia features produces a much
higher level-of-detail (LOD), efective and eficient algorithms are required to process these
feature graphs. The basis for the definition of these algorithms is a transformation of graphs
into another mathematical space for optimized calculations.
      </p>
      <p>
        Graph Codes are a 2D projection of MMFGs and perform calculations based on matrix
algorithms instead of graph traversal algorithms and also support the higher LOD of MMFGs
[
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. For these Graph Codes, we introduced a metric for similarity calculation, the mathematical
concepts of the indexing and retrieval algorithms, as well as a detailed evaluation regarding
performance, precision, and recall. This evaluation compares Graph Codes algorithms for
indexing and retrieval with the corresponding graph-traversal-based algorithms and shows,
that Graph Code algorithms need linear processing time instead of exponential time for
graphtraversal algorithms. Thus, for typical MMIR applications, Graph Codes are 5-10 times faster
and due to the higher LOD also more efective in terms of precision and recall. Basically, Graph
Codes are calculated on basis of an encoded valuation matrix   [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] of a graph (i.e. a
valued adjacency matrix). An encoding function  calculates a value for each position in
the matrix based on the MMFG’s feature nodes and edges. Rows and columns of such a Graph
Code represent the features of a MMFG, and thus the Graph Code Dictionary, which employs
the labels of each detected MMIR feature.
      </p>
      <p>
        Figure 1 briefly summarizes this concept as a foundation for the subsequent parts of this
paper. Figure 1a. shows a snippet of an exemplary MMFG visualized in a graph editing tool
[
        <xref ref-type="bibr" rid="ref19">19</xref>
        ], Figure 1b. illustrates a part of the MMFG in an object diagram including various node and
relationship types, which can be represented as a Graph Code table (see Figure 1c.) based on the
graph’s valuation matrix. A Graph Code’s matrix representation is shown in Figure 1d, where
the correspondence to mathematical matrix calculations is obvious. It is notable, that due to
the current object detection algorithms, MMFGs and their corresponding Graph Codes contain
feature information (e.g. "is a"), spatial information (e.g. "above"), and temporal information (by
the temporal ordering of sub-collections of Graph Codes) as well.
      </p>
      <p>
        To calculate MMIR results based on Graph Codes, a Graph Code Metric has been defined,
which can be applied for similarity or recommendation algorithms. In general, every detected
feature can be regarded as a Multimedia indexing term. The indexing term of any relevant feature
thus becomes part of the vocabulary of the overall retrieval index. In Multimedia Indexing and
Retrieval (MMIR), these terms typically have structural and/or semantic relationships to each
other and represent the basis for query construction and result presentation. In [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], defined a
metric for similary of Graph Codes, which is a triple  = ( ,  ,  ) containing a
feature-metric  based on the vocabulary (i.e. the similarity of common feature vocabulary
terms), a feature-relationship-metric   based on the possible relationships (i.e. the similarity
of edges between detected features), and a feature-relationship-type-metric  based on the
actual relationship types (i.e. the similarity of the edge types between features). This metric can
be applied for result presentation and has to be considered when constructing corresponding
queries.
      </p>
      <p>
        Current most commonly used Query Construction technologies include the employment
of structured query languages (e.g. SQL, OQL, XML-Query), as well as Visual query languages
(VQLs) and natural language querying (NL). An exemplary summary is given in [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ]. A Meaning
Driven Data Query Language (MDDQL) [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ] [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ], can be supportive for query construction
by system made suggestions of natural language based terms. In the field of Natural Language
Processing (NLP), several approaches have been made, to automatically translate natural
language into structured queries, e.g. NLP to SPARQL processing [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ] [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ]. The Query By Example
pattern [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ] employes a reference object to define a query for similar objects and the Relevance
Feedback interaction templace (including Explicit, Implicit and Pseudo Feedback) [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ] can be
applied to refine retrieval results. In the remainder of this paper, we will define Graph Code
query construction models based on these technologies. Typically, results of this kind of queries
are represented in form of ranked lists.
      </p>
      <p>
        In regards of the Result Presentation, often ranked lists are used to display results in
accordance with various relevance measures [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ]. Amongst the most common ones are similarity,
indicating the best matches for a given query. Result presentation including recommendations
(indicating connected or corresponding results), filters (employed to specify retrieval results),
and streaming (applied to live data) is typical for MMIR applications. All these technologies
provide a profound set of presentation possibilities, but have to be adapted or modified to utilize
the full potential of Graph Codes.
      </p>
      <p>
        For Semantic Querying, Indexing, and Retrieval, the Resource Description Framework
(RDF) and the Resource Description Framework Schema (RDFS) [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ] can serve as a foundation.
RDF covers the description of any kind of resource by employing XML Syntax, and RDFS can be
employed to represent domain specific vocabulary terms as a standardized model for structuring,
constructing, integrating, and interlinking semantic representation schemas. Building on RDF
and RDFS, querying can be performed by employing e.g., SPARQL, which is a standardized
query language and also supports the inclusion of semantic features. As RDF is based on XML,
it automatically can be represented in form of a graph model, which gives the opportunity to
employ a mapping to the MMFG also on a structural level. RDF-applications like publishing or
linking, as well as a shared data model and schema can act as a base layer for other technologies
[
        <xref ref-type="bibr" rid="ref27">27</xref>
        ] [
        <xref ref-type="bibr" rid="ref28">28</xref>
        ] [
        <xref ref-type="bibr" rid="ref29">29</xref>
        ] [
        <xref ref-type="bibr" rid="ref30">30</xref>
        ]. Our work is designed to closely relate to these existing standards.
      </p>
      <p>In summary, we can state that current technologies provide a suficient set appropriate
algorithms, tools, and concepts for extracting features of Multimedia content. Integrating data
structures as, e.g. the MMFG can fuse this information and compile it into a large feature
graph structure. However, the need to fuse many features into graphs to increase efectiveness
contradicts the demand of higher performance for retrieval, as graph-traversal algorithms
become less eficient with an increasing number of nodes and edges. Graph Codes can be applied
for MMIR to eficiently perform feature-based calculations in a 2D space. Query construction
can utilize existing structured query languages. However, these languages will be not intuitive
enough for the user. Therefore, particularly for MMIR applications, an easy-to-use and
easy-tounderstand query construction is required. In the remainder of this paper, we will illustrate
our approach for query construction and result presentation as well as our proof-of-concept
implementation for MMIR applications based on Graph Codes.</p>
    </sec>
    <sec id="sec-3">
      <title>3. Modeling and Design</title>
      <p>
        For the design of our solution, we follow the User Centered System Design approach, described by
[
        <xref ref-type="bibr" rid="ref31">31</xref>
        ] and use UML [
        <xref ref-type="bibr" rid="ref32">32</xref>
        ] as a modelling language. The software design follows the GoF-Patterns
[
        <xref ref-type="bibr" rid="ref33">33</xref>
        ] for reusable software components. For UI/UX-Design we apply the concept of Storyboards
[
        <xref ref-type="bibr" rid="ref34">34</xref>
        ] to illustrate the interaction between user and application.
      </p>
      <p>Potential relevant Use Cases are illustrated in Figure 2. In this paper we focus on the Use
Cases Manual Query Construction, Query By Example, Query Adaptation including Relevance
Feedback for Query Construction and the Use Cases Result Presentation, Recommendation, and
Filtering for Result Presentation. In the context of this paper, an Asset is a Multimedia object,
like an image, video- or audio-file, or connected textual information.</p>
      <p>
        For query construction based on Graph Codes we identified 3 possible and appropriate options:
the application of the Query by Example paradigm [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ], a manual construction of a query Graph
Code , or an adaptation of existing Graph Codes including Relevance Feedback. For
each of these option, a separate user interaction template can be defined, which describes the
user interface (including options) and the algorithm for query construction within the MMIR
application. In terms of Graph Codes, this means, that each of these options somehow has to
calculate a  Graph Code, which is then processed within the GMAF to produce a ranked
result list based on the Graph Code metrics. In the following subsections, we will describe each
of these options.
      </p>
      <sec id="sec-3-1">
        <title>3.1. Query By Example</title>
        <p>
          Query construction can be based on the Query by Example paradigm [
          <xref ref-type="bibr" rid="ref24">24</xref>
          ]. In this case, a
 is represented by an already existing Graph Code, which is typically selected by the
user to find similar assets in the collection of a MMIR application. A storyboard of this Use
Case is illustrated in Figure 3.
        </p>
        <p>In this Use Case, the user can select an asset from the collection of MMFGs. This selection
is then represented in detail and in form of its Graph Code representation. If the user presses
the Button "Use As Query", the Graph Code of the selected MMFG is set as . Then,
the query is executed and the list of results is re-ordered according to the similarity between
 and each asset in the collection.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Manual Query Construction</title>
        <p>A manual construction of a     by users also results in a  Graph Code,
which then is employed for querying. This manual construction can be performed in various
ways, which can be illustrated as follows (see Figure 4):</p>
        <p>In the following, we will describe three modalities of manual query construction:
keywordbased querying, structured query languages and natural language processing.</p>
        <p>
          Keyword-based Querying is a very simple manual scenario, in which the user is able to
enter keywords into a textfield of the application’s User Interface (UI). These keywords will be
internally transformed into a Graph Code, which is then applied as a  object for query
execution. This method is only applicable for queries based on the MMIR application’s dictionary
(i.e. the set of all Graph Codes’ vocabulary terms) as a keyword-based entry does not allow the
specification of relationships or relationship types. In this case, only the metric  can be
applied. In many cases, this method will provide an easy-to-use UI and accurate retrieval results.
An illustration is shown in Figure 4. However, one major problem of keyword-based querying is,
that the user somehow has to have information about valid vocabulary terms of the collection.
This can be achieved by presenting a taxonomy [
          <xref ref-type="bibr" rid="ref35">35</xref>
          ] or more semantic information [
          <xref ref-type="bibr" rid="ref27">27</xref>
          ] to the
user. If such a taxonomy is not available, at least a underlying dictionary with synonyms should
be employed to map entered terms to valid vocabulary terms. In our modelling, we will address
this topic also by Query Refinement , which is illustrated in section 3.3.
        </p>
        <p>
          As a second modality, Structured Query Languages can be appleid to Graph Codes, as well.
As the set of vocabulary terms of an MMIR collection can be represented by RDFS, the user can
be also enabled to formulate queries in a structured language (e.g. SQL or SPARQL). In this case,
the semantic of the textfield’s content can be automatically changed to support a structured
query. As structured query languages are based on grammars, an automated detection of the
language is possible (e.g. by applying the Interpreter Pattern [
          <xref ref-type="bibr" rid="ref33">33</xref>
          ]). For each structured query
language, the MMIR application has to define a translation into Graph Codes. One big advantage
of structured query languages is, that relationships and relationship types can be formulated as
well and thus also the metrics   and  can be applied. A SPARQL query for the MMFG
shown in Figure 1 can be formulated as follows:
        </p>
        <p>SELECT ? x ? y ? z
WHERE {
}
? x r d f s : s u b C l a s s O f : h a t .
? x mmfvg : a t t r i b u t e : a b o v e .
? y r d f s : s u b C l a s s O f : P e r s o n .
? y mmfvg : name : J i m .</p>
        <p>? z mmfvg : t y p e : Image
Structured Query Input also follows the Storyboard shown in Figure 4. However, entering
structured queries is dificult for many users. Amongst others, one common solution for this
could be the processing of natural language, which is described in the next subsection.</p>
        <p>
          Thirdly, Natural Language Processing (NLP) can be employed to enhance MMIR
applications for querying. In many applications, natural language input can enable users to formulate
complex queries. Natural language can be entered by writing or in spoken form, which is then
typically transcribed by NLP-processors. In any case, the query textfield will contain some kind
of natural language query. There are several approaches, that are able to translate NLP into
structured query languages like SPARQL [
          <xref ref-type="bibr" rid="ref23">23</xref>
          ].
        </p>
        <p>In general, manual query construction will provide an initial , but in many cases,
this query Graph Code has to be refined. As this refinement can be applied to any of the so far
presented approaches, it will be detailed and summarized in the next section.</p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Query Adaptation</title>
        <p>An adaptation of an existing Graph Code an existing  can lead to a refined  as
well. A refinement in terms of Graph Codes means, that e.g. some non-zero fields are set to zero,
or that some fields get new values assigned according to the Graph Code encoding function
, or that some new rows and columns are added to the Graph Codes. This Use Case can be
applied to both Quer By Example and Manual Query Construction as a refinement.</p>
        <p>From a UI perspective, this method requires both the maintenance of a Graph Code’s dictionary
(i.e. its vocabulary terms), and the possibility to modify corresponding relationships and
their types. Until now, we employed a table representation for Graph Codes, which is a good
representation or view. But for manipulating Graph Codes in a UI, other methodologies are
more suitable and easier to use. Figure 5 shows an optimized workflow for query adaptation, to
which all the Graph Code metrics ( ,  ,  ) can be applied.</p>
        <p>
          To adapt or modify a , whe user can maintain a list of vocabulary terms. These
terms can either be suggested by the system based on the underlying taxonomy, thesaurus,
or ontology, which would give the user the option to select these terms from a pre-defined
list. In this case, only relevant terms of a collection’s vocabulary could be applied for query
adaptation. But, as Graph Codes also include semantic information and relationships to semantic
knowledge-graphs like [
          <xref ref-type="bibr" rid="ref36">36</xref>
          ], even manually entered terms can be resolved and mapped to entries
of the MMIR application’s collection. These terms will be used for retrieval based on the metric
 .
        </p>
        <p>
          Once a set of terms is defined by the user, the MMIR application provides an option to "draw"
relationships between these terms. Any kind of relationship can be utilized by the metric
 . A very good example for such an UI behaviour is given by yED [
          <xref ref-type="bibr" rid="ref19">19</xref>
          ] for graph-based
manipulations. Once a relationship is defined between two terms, the MMIR application will
ask the user for the relationship-type, which will be relevant for the application of the metric
 . Once the user has constructed and refined a  in this way, the represented query
can be executed by the MMIR application similar to the already described Use Cases.
        </p>
        <p>
          The options presented in this section are already implemented in the current GMAF prototype
for Graph Code querying. The current prototype is illustrated in more detail in section 4 and
available on Github [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ].
        </p>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Information Retrieval based on Graph Codes</title>
        <p>For information retrieval, we utilize a retrieval function  () = (1, ..., ),
which returns a list of Graph Codes ordered by relevance implemented on basis of the similarity
metric  = ( ,  ,  ) and thus directly represents the retrieval result in form of a
ranked list. It is notable, that the calculation of this ranked list can be performed in parallel, if
specialized hardware is available.</p>
        <p>
          For a given query Graph Code , a similarity calculation with each Graph Code 
of the collection is performed, based on the Graph Code metric  . Compared to graph-based
operations, matrix-based algorithms can be highly parallelized and optimized. In particular,
modern GPUs are designed to perform a large number of independent calculations in parallel
[
          <xref ref-type="bibr" rid="ref37">37</xref>
          ]. Thus, the comparison of two Graph Codes can be done in (1) on appropriate hardware.
Even current Smartphones or Tablets are produced with specialized hardware for parallel
execution and ML tasks like Apple’s A14 bionic chip [
          <xref ref-type="bibr" rid="ref38">38</xref>
          ]. Therefore, the Graph Encoding
Algorithm also performs well on Smartphones or Tablets.
        </p>
        <p>
          In [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ], we provided detailed facts and figures. To calculate the ranked result list, this algorithm
thus utilizes the three metrics  ,   and  in a way, that first, the similarity according
to  (i.e. equal vocabulary terms) is calculated. For those elements, that have equal vocabulary
terms, additionally the similarity value of   for similar feature relationships is applied for
ordering. Also, for those elements with similar relationships (i.e. edges), we also apply the
metric  , which compares edge types. Hence, the final ranked result list for a 
Graph Code is produced by applying all 3 Graph Code metrics to the collection.
        </p>
      </sec>
      <sec id="sec-3-5">
        <title>3.5. Result Presentation</title>
        <p>
          There are several options for result presentation. In the context of this paper, we focus on the
presentation as a ranked list, as this is the most common form in MMIR applications. Other
forms will be part of future work. For presenting the results as a ranked list, the UI has to
provide a list of assets. In order to illustrate the similarity values of these assets, the values of
each metric should be displayed for each element of the ranked result list. Results are typically
presented with the help of preview images and ordered according to their relevance. Relevance
itself can be defined in various forms [
          <xref ref-type="bibr" rid="ref25">25</xref>
          ], two of the most common forms are initially applied
to Graph Codes: similarity and recommendations.
        </p>
        <p>Similarity: to show a list of similar assets within a Graph Code based MMIR application, the
Graph Code metric is applied as follows:
for each GC in collection
calculate the intersection matrices of GC_Query and GC
calculate M_F of GC_Query and GC
calculate M_FR of GC_Query and GC
calculate M_RT of GC_Query and GC
order result list according to
value of M_F
value of M_FR where M_F is equal</p>
        <p>value of M_RT where M_F and M_FR are equal
return result list</p>
        <p>This algorithm first compares  , i.e. the vocabulary terms of two Graph Codes. If they have
a similar set of vocabulary terms, the metric   is applied to determine, if the vocabulary
terms are somehow connected to each other. And finally, the metric   is employed to check,
if the relationship type of the connection between two vocabulary terms is the same. This
produces the most similar result to a given .</p>
        <p>Recommendations are retrieval results, that typically extend a result list by including assets,
that are somehow relevant for the current query. In case of Graph Codes, this can be achieved
by applying a diferent order of metrics to a result list:
for each GC in collection
calculate the intersection matrices of GC_Query and GC
...
order result list according to
value of M_FR</p>
        <p>value of M_F where M_FR is equal
return result list</p>
        <p>This algorithm first employes the metric  , which denotes, that in the asset and the query
object, a link between two common features has been found, independent from other matching
vocabulary terms. Thus, even if only two vocabulary terms are matching, this metric represents
the assumption, that a common link between these terms indicates, that the asset is somehow
extending the query object and thus represents some kind of recommendation. Depending on
the MMIR application, typically the metric  is applied additionally to order these relevance
results according to their similarity as well. The metric  does not have to be applied for
recommendations.</p>
      </sec>
      <sec id="sec-3-6">
        <title>3.6. Summary</title>
        <p>In this section we discussed several UI-models for query construction and result presentation.
This modeling provides a flexible and extensible design and can be implemented in standalone
applications for MMIR, as well as in web applications or for mobile apps. The use cases Manual
Query Construction based on keywords, structured query languages or NLP, Query By Example
utilizing existing similar assets, and Query Adaptation providing a highly sophisticated UI for
query construction, can be employed to create or refine Graph Code queries. The query result
will be typically presented as a ranked list. In our current GMAF prototype, we implemented
most of the concepts shown in this section. The following section will give a brief exemplary
detail on this. Technologies like filtering or streaming will be part of our future work.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Implementation</title>
      <p>
        For the implementation of algorithms and concepts, we chose Java [
        <xref ref-type="bibr" rid="ref39">39</xref>
        ] as programming
languages, as our corresponding frameworks like the Generic Multimedia Analysis Framework [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]
are already implemented in Java. As the implementation basically follows the algorithms and
functions described in the last section, the details of the implementation including source code
can be found at Github [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. In this prototype (see Figure 6), we use Java Swing as a UI language
and utilized its existing Model View Controller [
        <xref ref-type="bibr" rid="ref33">33</xref>
        ] architecture and event model.
      </p>
      <p>For example, the Use Case Keyword-based Querying as discussed in section 3.2 has been
correspondingly implemented in java as shown in Figure 7. For the implementation of the result
presentation in form of a ranked list based on similarity and including additional
recommendations for a selected asset For the implementation of similarity and recommendations, we
implemented the algorithms as described in section 3. In the UI, we represent similar assets and
recommended assets as illustrated in Figure 8.</p>
      <p>Figure 6 shows a complete screenshot of the current Graph Code MMIR application. The
button "Query from GC" starts a Query By Example search based on the selected asset. Below
each result, the corresponding metric is displayed for research and refinement purposes and to
provide the experienced user a deeper insight into the ranking. The detail view (right section
of the screen) shows a preview of the selected asset and additional information like similarity,
recommendations, the Graph Code and a semantic extension to Graph Codes, when a mapping
to existing semantic ontologies can be established. The current prototype is based on images
and text only. Further Multimedia asset types are part of our ongoing work. But basically, the
UI concepts for Graph Code querying and result presentation are completely independent from
the Multimedia asset type.</p>
      <p>With our current prototypical implementation, we can prove the concept and validity of
Graph Codes and the corresponding Query Construction and Result Presentation algorithms. Our
implementation shows, that Graph Codes can be employed for eficient and efective MMIR.
Especially the Use Cases Manual Query Construction, Query By Example, Query Adaptation, and
Result Presentation including Recommendation can be implemented based on Graph Codes and
utilize a high LOD. However, a detailed evaluation has not yet been finalized and will be part
of our future work. Currently, only a basic dictionary for english synonyms is employed in
the prototype. As part of our ongoing work, we are specifying and implementing semantic
extensions to RDF, ontologies, and the semantic web to provide a semantic and intelligent
querying as well.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion and Future Work</title>
      <p>In this paper we presented a UI modeling for MMIR applications using Graph Codes, which
significantly improve the level-of-detail, efectiveness and eficiency for MMIR applications. In
order to utilize this technology, several aspects of UI design have to be respected. We showed
our model for Query Construction and Result Presentation as well as some implementation
details and the current UI prototype of the GMAF framework. Open challenges are the complete
integration of the Use Case Query Adaptation with a highly sophisticated UI, and the support
for further Multimedia asset types. Additionally, implementations for mobile devices, tables and
implementations as plugins for other existing MMIR applications, will be part of our research
and development roadmap based on the Graph Code technology.</p>
    </sec>
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