=Paper= {{Paper |id=Vol-1176/CLEF2010wn-ImageCLEF-BenaventEt2010 |storemode=property |title=Experiences at ImageCLEF 2010 using CBIR and TBIR Mixing Information Approaches |pdfUrl=https://ceur-ws.org/Vol-1176/CLEF2010wn-ImageCLEF-BenaventEt2010.pdf |volume=Vol-1176 }} ==Experiences at ImageCLEF 2010 using CBIR and TBIR Mixing Information Approaches== https://ceur-ws.org/Vol-1176/CLEF2010wn-ImageCLEF-BenaventEt2010.pdf
       Experiences at ImageCLEF 2010 using CBIR and
           TBIR mixing information approaches

       J. Benavent2, X. Benavent2, E. de Ves2, R. Granados1, Ana García-Serrano1
                    1 Universidad Nacional de Educación a Distancia, UNED
                                   2 Universidad de Valencia

                           xaro.benavent@uv.es, agarcia@lsi.uned.es



       Abstract. The main goal of this paper it is to present our experiments in
       ImageCLEF 2010 Campaign (Wikipedia retrieval task). This edition we present
       a different way of using textual and visual information based on the assumption
       that the textual module better captures the meaning of a topic. So that, the TBIR
       module works firstly and acts as a filter, and the CBIR system reorder the
       textual result list. The CBIR system presents three different algorithms: the
       automatic, the query expansion and a logistic regression relevance feedback
       algorithm. We have submitted nine textual and eleven mixed runs. Our best run,
       at the 34th position (25% at the first result list), is a textual run using our own
       implemented algorithm based on a VSM approach and TF-IDF weights
       (included in the IDRA tool) and all languages for annotation and for the topics.
       Our best mixed run (51th position is at 60% first result list) is using the textual
       list and the logistic regression relevance algorithm at the CBIR module. Most of
       our runs are above the average of its own modality for the different measures.
       The new system architecture with the IDRA tool for the textual module and the
       logistic regression relevance algorithm for the visual module are the right track
       to maintain in our research lines.


Keywords: Information Retrieval, Textual-based Retrieval, Content-Based Image
Retrieval, Relevance feedback, Merge Results Lists, Fusion, Indexing.
Categories and subject descriptors
H.3 [Information Storage and Retrieval]: H.3.1 Content Analysis and Indexing; H.3.2
Information Storage; H.3.3 Information Search and Retrieval; H.3.4 Systems and Software;
H.3.7 Digital libraries. H.2 [Database Management]: H.2.5 Heterogeneous Databases; E.2
[Data Storage Representations].



1 Introduction

The UNED-UV is a research group formed by researchers from two different
universities in Spain, the Universidad Nacional de Educación a Distancia (UNED)
and the Valencia University (UV). This research group is working together [1] [2]
since ImageCLEF08 edition.
   The main goal of this paper it is to present our experiments in ImageCLEF 2010
Campaign (Wikipedia retrieval task) [3]. This ImageCLEF edition our group presents
a different way of working using the information of the Content Based Image
Retrieval (CBIR) system and the information of the Textual Based Image Retrieval
(TBIR) system. The global system is based on the assumption that the conceptual
meaning of a topic is initially better captured by the text module itself than by the
visual module. Therefore, the TBIR system works firstly over the whole database
working as a filter, and then the CBIR system reorders the filtered textual result list.
In this way, the CBIR system acts also as a merging module.
   The TBIR subsystem includes the UNED own implemented tool IDRA (InDexing
and Retrieving Automatically) [4] that includes several functionalities, including an
algorithm based on the Vector Space Model (VSM) approach using TF-IDF weighted
vectors. The CBIR subsystem includes three different algorithms: the automatic, the
query expansion and UV own logistic regression relevance feedback algorithm [5].
   A more detailed presentation of the system, the submitted experiments, and the
obtained results is included in the following sections.


2 System Description

The global system (shown at Fig. 1) includes three main subsystems: the TBIR, the
CBIR and the merging module. The TBIR subsystem uses the UNED own
implemented tool IDRA [5], in charge of indexing and retrieving textual annotations
from images. The Valencia University CBIR system implements for this ImageCLEF
edition three different algorithms: the automatic, the query expansion and the
relevance feedback algorithm based on logistic regression [5]. The TBIR subsystem
acts firstly over the whole images of the database, acting as a filter to the CBIR
system selecting the relevant images for a certain query. In a second step, the CBIR
system works over the set of filtered images reordering this list taking into account
the visual information of the image. The CBIR system generates different visual result
lists depending on the number of query images (for the automatic and the query
expansion algorithm). These lists are merged by the merging module by an OWA
operator [6].


2.1 Text-based Index and Retrieval

This module is in charge of the textual image retrieval using the metadata supplied for
the images in the collection. IDRA tool [4] extracts, selects, preprocesses and indexes
the metadata information, for later search and retrieve the most relevant images for
the queries. After this process, a ranked results list is obtained for each textual
experiment.
   The textual retrieval task architecture can be seen in the Fig. 1. Each one of the
components takes care of a specific task. These tasks will be sequentially executed:
                                                                                      TXT
                             Index         Metadata                                  Results
                             Lang          Selection          texts       IDRA
                                                                                      List
                                                                          Index
                             Text
                                                      PRE-
                           Extraction
                                                    PROCESS
      COLLECTION                                                          IDRA
       (XML files)        TBIR                           queries          Search


      T                                 Queries
      O TITLEs                           File                         M
      P                   Queries
                                                                      E     MAX
                                                                      R
      I Example            Lang                                       G     merge
      C Images                                                        E
      S
                                                  Automatic                 OWA
                                                                            Fusion
      COLLECTION            Feature                 Query                            TXTIMG
        (images)           Extraction             Expansion                           Results
                                                                                       List
                                                  Relevance
                          CBIR                    Feedback


                                    Fig. 1. System overview.

Text Extraction. Extracts the text from the files which contains the associated
metadata. It uses the JDOM Java API to identify the content of each of the tags of the
XML files.
Preprocess. This component process the text in two ways: 1) special characters
deletion: characters with no statistical meaning, like punctuation marks, are
eliminated; and 2) stopwords detection: exclusion of semantic empty words from
specifics lists for each language. When processing multilingual text, a manually join
of these lists is used.
Metadata Selection. With this component the system selects the text we want to
index, depending on the chosen language “Index Lang” (EN, FR, DE or ALL).
Therefore, 4 different indexations will be generated: one multilingual and three
monolingual.
   In the case of the monolingual indexations the selected text for the chosen
language L= {EN, FR, DE}, from images metadata files, will be: 1) 
whenever there is specific metadata for language L, or when there is not for any
language; 2)  and  whenever there is specific metadata for L;
3)  when the text in this tag is not contained in  or
 and therefore will add new information. This time we did not use the text
from the corresponding Wikipedia articles indicated in the  attribute
“article”.
   When carrying out the multilingual indexation (ALL), the selected text will be the
concatenation of the corresponding text for each of the three languages (EN+FR+DE),
in the same way as explained for the monolingual cases.
Queries File. 4 different queries files are constructed for the experiments: one for
each language (EN, FR, DE), and another for the multilingual case, which is indicated
in “Queries Lang”. The strategy to select the text for each query is just to extract the
information in the  tag for the chosen language, and the concatenation of the
three languages for the multilingual experiment.
IDRA Index. This component indexes the selected text associated with each image.
The indexation is based on the VSM approach using TF-IDF (term frequency –
inverse document frequency) weighted vectors. This approach consists in calculating
the weights vectors for each one of the images selected texts. Each vector is
compounded by the TF-IDF weights values of the different words in the collection.
TF-IDF weight is a statistical measure used to evaluate how important a word is to a
text in a concrete collection, and is calculated as shown in (1).
                           ⎛N⎞        ti,j: number of occurrences of the word tj in caption text Ti.
 TF − IDF = ti , j * log 2 ⎜ ⎟        N: total number of images captions in the collection.                (1)
                           ⎝ ni ⎠     ni: number of captions in which appears the word ti.


   All weights values for each vector will be then normalized using the Euclidean
distance. Therefore, for each one of the words appearing in the collection, the IDRA
Index process updates and stores the following values: ni, ti,j, N (described in (1)), Ti:
unique identifier of the image, idfj: inverse document frequency ( log2(N/ni) ) in Ti, Ei:
Euclidean distance used to normalize, and wj,i: weight of word tj in Ti.
IDRA Search. Is in charge of launching the queries against a concrete indexation for
the experiment, and it obtains the corresponding “TXT Results List”. For each one of
the queries, IDRA calculates its corresponding weights vector in the same way as in
indexation. Then, the similarity between the query and an image text will depend on
the proximity of their associated vectors calculated by the cosine measure:


                 sim (T i , q ) = cos( Ö ) =
                                                  ∑ w *w              j, i   j, i
                                                                                                     (2)
                                               ∑w w * ∑w
                                                      j, i *   j, i                 q, i *   wq, i

  This similarity value will be calculated between the query and all the images
metadata indexed. Images are ranked in descending order in the “TXT Results List”.


2.2 Content-Based Information and Visual Retrieval

The VISION-Team at the Computer Science Department of the University of
Valencia has its own CBIR system, and that has also been used in previous
ImageCLEF editions (Photo-retrieval task in 2008 and 2009 [1] [2]). The low-level
features of the CBIR system have been adapted for the images of the new image
collection (WikipediaMM 2010) taking into account the results of the previous
editions.
   As in most CBIR systems, a feature vector represents each image. The first step at
the Visual Retrieval system is extracting these features for all the images on the
database as for each of the cluster query topic images for each question. Instead of
using the low-level features provided by the organization, we have used our own
features. We use different low-level features describing color and texture to build a
vector of features. The number of low-level features has been increased from the 114
components at ImageCLEF09 up to 296 components at the current edition. This
increment is mainly due to the use of local HS histogram (10x3 bins) instead of local
H histograms (10 bins) descriptors in previous editions.
     • Color information: Color information has been extracted calculating both
          local and global histograms of the images using 10x3 bins on the HS color
          system. Local histograms have been calculated dividing the images in four
          fragments of the same size. A bidimensional HS histogram with 10x3 bins is
          computed for each patch. Therefore, a feature vector of 30 components for
          the global histogram, and 192 components for the local histograms represent
          the color information of the image.
     • Texture information: Two types of texture features are computed: The
          granulometric distribution function, using the coefficients that result of
          fitting the distribution function with a B-spline basis. And, the Spatial Size
          Distribution. We have used two different versions of it by using as the
          structuring elements for the morphological operation that get size both a
          horizontal and a vertical segment [1].

   At this edition, the vision team has focus his work in testing three different visual
algorithms applied to the results retrieved by the text module: the automatic, the
relevance feedback and the query expansion. We assume that the conceptual meaning
of a question is better captured by the text module than by a visual module when they
work individually. Therefore, the task of the visual module is to re-order the textual
result list taking into account the information of the query images given at each topic.
Automatic algorithm. This is the typical algorithm in a CBIR system. The first step
is to calculate the feature vector that describes each image of the database as it has
been explained at the previous paragraph. The second step is to calculate the
similarity measurement between the feature vectors of each image on the database
and the N query images. The distance metric applied in our experiments is the
Mahalanobis distance that gives better results than the Euclidean one ([1]). The
Mahalanobis distance gives better results than the Euclidean due to the fact that this
measure takes into account the correlations of the data set and is scale-invariant being
this characteristic very useful because the broad differences between the different
low-level feature values. The Mahalanobis distance needs to pre-calculate the
covariance matrix of the sample data. Since, the size of the database is too huge we
have chosen a different approach: a covariance matrix is computed for each textual
result list given for each topic. Thus, we have managed to cope with the problem of
computing the metric for the Mahalanobis distance in a large database.
   As we have N query images, we will obtain N visual result lists, one for each query
image in the topic. These N result lists are passed to the merging module to fuse them
in one result list.
Query expansion algorithm. The query expansion algorithm works in the same way
that the automatic algorithm, being the only difference that this algorithm expands the
N query images to a wider set of images M. Thus, the M query images set is
composed of the N images given by the topic and the N’ expanded images being
M=N+N’. The N’ images set are the 3 first images of the textual result list. The M
result lists are passed to the merging module.
Relevance feedback algorithm based on logistic regression. This algorithm works
differently to the two previous ones. Therefore, we will explain the concept of
relevance feedback and the adjustments made to get a good performance of the
algorithm for the proposed tasks [5]. Relevance feedback is a term used to describe
the actions performed by a user to interactively improve the results of a query by
reformulating it. An initial query formulated by a user may not fully capture his/her
wishes. Users then typically change the query manually and re-execute the search
until they are satisfied. By using relevance feedback, the system learns a new query
that better captures the user’s need for information. The user enters his/her
preferences at each iteration through the selection of relevant and non-relevant
images.
   We will explain the way the logistic regression relevance feedback algorithm
works. Let us consider the (random) variable Y giving the user evaluation where Y=1
means that the image is positively evaluated and Y=0 means a negative evaluation.
Each image in the database has been previously described by using low-level features
in such a way that the j-th image has the k-dimensional feature vector xj associated.
Our data will consist of (xj, yj), with j=1,…,n, where n is the total number of images,
xj is the feature vector and yj the user evaluation (1=positive and 0=negative). The
image feature vector x is known for any image and we intend to predict the associated
value of Y. In this work, we have used a logistic regression where P(Y=1|x) i.e. the
probability that Y=1 (the user evaluates the image positively) given the feature vector
x, is related with the systematic part of the model (a linear combination of the feature
vector) by means of the logit function. For a binary response variable Y and p
explanatory variables X1,…,Xp, the model for π(x)=P(Y=1|x) at values x=(x1,…,xp)
of predictors is logit[π(x)]=α+β1x1+…+βpxp, where logit[π(x)]=ln(π(x)/(1- π(x))).
The model parameters are obtained by maximizing the likelihood function given by:
                                    n
                         l ( β ) = ∏ π ( xi ) yi [1 − π ( xi )]1− yi                (3)

   The maximum likelihood estimators (MLE) of the parameter vector β are
calculated by using an iterative method.
   We have a major difficulty when having to adjust a global regression model in
which we take the whole set of variables into account, because the number of selected
images (the number of positive plus negative images) is typically smaller than the
number of characteristics. In this case, the regression model adjusted has as many
parameters as the number of data and many relevant variables could be not
considered. In order to solve this problem, our proposal is to adjust different smaller
regression models: each model considers only a subset of variables consisting of
semantically related characteristics of the image. Consequently, each sub-model will
associate a different relevance probability to a given image x, and we face the
question of how to combine them in order to rank the database according to the user’s
preferences. This problem has been solved by means of an ordered averaged weighted
operator (OWA) [6].
   In our case, we have adapted the manual relevance feedback to an automatic
performance. The examples and the counter-examples (positive and negative images)
are automatically selected for each topic. The examples are the query images of the
topic plus N images taken from the first positions of the textual result list. The
counter-examples are the M latest positions of the textual result list. The relevance
feedback algorithm is executed once.


2.4 Merging Algorithms

Two merging algorithms are used in different steps with different purposes.
OWA Fusion. In the modality for textual and visual retrieval the approach that
follows this edition is based on the assumption that the conceptual meaning of a topic
is initially better captured by the text module itself than by the visual module. Thus,
the textual module works as a filter for the visual module, and the work of the visual
module is to re-order the textual results list. In this way, there has not been used an
explicit fusion algorithm to merge the textual result list and the visual result list.
However, the visual module generates N result visual lists depending on the number
of query images for the automatic and query expansion algorithms. These N lists are
merged in one result final list by using the Mathematical aggregation operators OWA
[6]. The OWA transform a finite number of inputs into a single output and play an
important role in image retrieval. With the OWA operator no weight is associated
with any particular input; instead, the relative magnitude of the input decides which
weight corresponds to each input. In our application, the inputs are similarity
distances to each of the N query images and this property is very interesting because
we do not know, a priori, which image of the N images will provide us with the best
information. The aggregation weights used for these experiments are the weights
which correspond to the maximum, that is an OR operator.
MAXmerge. This algorithm is used to fuse together different results lists in order to
carry out some experiments related to multilingualism (UNED-UV8, UNED-UV9
described in next section). MAXmerge algorithm is included in IDRA tool and
consists on, for each query, to select the results from the different lists which have a
higher relevance/similarity value for the corresponding query, independently of the
list the results appears in.


3 Experiments (submitted runs)

We have participated in two modalities: textual and mixed retrieval (visual and
textual). Finally, 20 runs were submitted (9 textual, 11 mixed). A schematic
description of these runs is shown in Table 1.
   For textual modality, we present 9 runs. As it is explained in previous sections, 4
different indexations and 4 queries files were generated. From all possible
combinations, we were interested in evaluate experiments with the 4 queries files
against the multilingual indexation, obtaining 4 runs: UNED-UV1 (with multilingual
queries), UNED-UV2 (with English queries), UNED-UV4 (with French queries), and
UNED-UV6 (with Dutch queries). UNED-UV3, UNED-UV5 and UNED-UV7
correspond to monolingual experiments in which the language for the indexation is
the same of the queries: English, French or Dutch, respectively. Finally, 2 more
textual runs were submitted using the MAXmerge fusion algorithm: UNED-UV8
merging results lists from UNED-UV2, UNED-UV4 and UNED-UV6; and UNED-
UV9 merging results from UNED-UV3, UNED-UV5 and UNED-UV7.
   In the mixed modality, the textual module has passed through the visual module
four different kinds of its basic textual algorithms corresponding to the UNED-UV1,
UNED-UV2, UNED-UV3 and UNED-UV9 runs. The visual module has applied its
three different algorithms (automatic, relevance feedback and query expansion) to the
textual result lists in order to test the performance of these three algorithms over the
different kind of text algorithms retrieval. For the [UNED-UV1] basic line the
automatic, relevance feedback and query expansion algorithms have been applied
getting the three corresponding runs [UNED-UV10], [UNED-UV11] and [UNED-
UV12]. Following the same structure applying the three different visual algorithms to
the [UNED-UV2] run the [UNED-UV13], [UNED-UV14] and [UNED-UV15] runs
are obtained. From the [UNED-UV3] run the [UNED-UV16], [UNED-UV17] and
[UNED-UV18]; and, from the [UNED-UV9] the [UNED-UV19], [UNED-UV20] and
[UNED-UV21]. The last one was out of the maximum runs submitted.

Table 1. Submitted textual and mixed experiments.

                    CBIR                            TBIR
                                                           Annotation   Topic
Run         Mod     Algor   Algorithm                      language     language
UNED‐UV1    Text       ‐    VSM                            EN+FR+DE     EN+FR+DE
UNED‐UV2    Text       ‐    VSM                            EN+FR+DE     EN
UNED‐UV3    Text       ‐    VSM                            EN           EN
UNED‐UV4    Text       ‐    VSM                            EN+FR+DE     FR
UNED‐UV5    Text       ‐    VSM                            FR           FR
UNED‐UV6    Text       ‐    VSM                            EN+FR+DE     DE
UNED‐UV7    Text       ‐    VSM                            DE           DE
UNED‐UV8    Text       ‐    VSM (EN+FR+DE) + MAXmerge      EN+FR+DE     EN+FR+DE
UNED‐UV9    Text       ‐    VSM (EN|FR|DE) + MAXmerge      EN+FR+DE     EN+FR+DE
UNED‐UV10   Mixed   AUTO    [UNED‐UV1]                     EN+FR+DE     EN+FR+DE
UNED‐UV11   Mixed   FB      [UNED‐UV1]                     EN+FR+DE     EN+FR+DE
UNED‐UV12   Mixed   QE      [UNED‐UV1]                     EN+FR+DE     EN+FR+DE
UNED‐UV13   Mixed   AUTO    [UNED‐UV2]                     EN+FR+DE     EN
UNED‐UV14   Mixed   FB      [UNED‐UV2]                     EN+FR+DE     EN
UNED‐UV15   Mixed   QE      [UNED‐UV2]                     EN+FR+DE     EN
UNED‐UV16   Mixed   AUTO    [UNED‐UV3]                     EN           EN
UNED‐UV17   Mixed   FB      [UNED‐UV3]                     EN           EN
UNED‐UV18   Mixed   QE      [UNED‐UV3]                     EN           EN
UNED‐UV19   Mixed   AUTO    [UNED‐UV9]                     EN+FR+DE     EN+FR+DE
UNED‐UV20   Mixed   FB      [UNED‐UV9]                     EN+FR+DE     EN+FR+DE
4 Results

After the evaluation by the task organizers, our results for each of the submitted
experiments are presented in Table 2. The table shows that our two best results are for
the textual runs UNED-UV1 and UNED-UV9 (at the 34th and 40th position of the
global result list, this is at the 25% first results). For the mixed modality, the best
result is the UNED-UV11 at the 51th position (at the 60% first results). It is worth
pointing out that the ranking position is computed by using the MAP measure (with a
maximum MAP value of 0.1927 for our best run and a minimum MAP value of
0.1502 for our worst one). It can also be observed at Table 2 that most of our runs are
above the average for each own modality (textual and mixed runs). These above
results are marked in bold at the table.

Table 2. Results for the submitted experiments (The results in bold are above the average for
the modality).

      Po Run               Mode    MAP      P@10     P@20     R‐prec.   Bpref    NDCG
       34 UNED‐UV1         Text    0.1927   0.3914   0.3564   0.2663    0.2282   0.4092
       40 UNED‐UV9         Text    0.1865   0.4200   0.3636   0.2638    0.2253   0.4012
       51 UNED‐UV11        Mixed   0.1792   0.3914   0.3629   0.2514    0.2175   0.3887
       52 UNED‐UV8         Text    0.1790   0.3914   0.3350   0.2533    0.2150   0.4006
       59 UNED‐UV20        Mixed   0.1717   0.4071   0.3571   0.2499    0.2133   0.3803
       61 UNED‐UV2         Text    0.1627   0.3657   0.3293   0.2340    0.2002   0.3582
       68 UNED‐UV12        Mixed   0.1525   0.3943   0.3621   0.2236    0.1939   0.3341
       69 UNED‐UV10        Mixed   0.1502   0.3971   0.3607   0.2204    0.1920   0.3318
       70 UNED‐UV14        Mixed   0.1498   0.3543   0.3250   0.2203    0.1902   0.3387
       72 UNED‐UV19        Mixed   0.1427   0.4171   0.3671   0.2166    0.1872   0.3219
       76 UNED‐UV3         Text    0.1370   0.3871   0.3336   0.2146    0.1787   0.3168
       77 UNED‐UV15        Mixed   0.1286   0.3829   0.3386   0.1947    0.1687   0.2935
       78 UNED‐UV17        Mixed   0.1285   0.3614   0.3379   0.2047    0.1723   0.3049
       79 UNED‐UV13        Mixed   0.1261   0.3857   0.3307   0.1879    0.1650   0.2909
       83 UNED‐UV16        Mixed   0.1089   0.4043   0.3357   0.1728    0.1491   0.2588
       84 UNED‐UV18        Mixed   0.1077   0.3886   0.3307   0.1729    0.1492   0.2571
       88 UNED‐UV6         Text    0.0936   0.2671   0.2314   0.1312    0.1151   0.1885
       89 UNED‐UV4         Text    0.0920   0.2829   0.2536   0.1492    0.1301   0.2128
       97 UNED‐UV5         Text    0.0661   0.2943   0.2650   0.1156    0.1017   0.1703
      102 UNED‐UV7         Text    0.0603   0.2586   0.2221   0.0994    0.0851   0.1378
      Average              Text    0,1579   0,3961   0,3519   0,2277    0,1992   0,3622
      Best (pos 12)        Text    0,2361   0,4871   0,4393   0,3077    0,2694   0,5217
      Average              Mixed   0,1387   0,3701   0,3293   0,1982    0,1759   0,3319
      Best (pos 1)         Mixed   0,2630   0,6110   0,5410   0,3289    0,2970   0,5360

  With textual experiments this campaign we aimed to analyze multilingual issues.
Comparing UNED-UV1 results with UNED-UV2, UNED-UV4 and UNED-UV6
ones, we can observe that best retrieval with the multilingual indexation is performed
when we use the queries file constructed with the concatenation of all languages
(MAP=0.1927). Launching English queries obtains better results (0.1627) that French
(0.0920) or Dutch (0.09936), surely due to the metadata information for that
language. Analyzing results for UNED-UV8 an UNED-UV9 runs, we observe that
both of them obtain a good performance (only UNED-UV1 obtains higher MAP than
them). Slightly higher results are for UNED-UV9 (0. 1865 > 0. 1790), so it is early to
conclude when merging results from different languages, if it is better to launch the
queries against monolingual indexations than against multilingual. At this moment,
the effort in preprocessing has to be taken into account to decide.
    The process to analyze our mixed modality results is by the comparison of the
basic textual algorithms (UNED-UV1, UNED-UV2, UNED-UV3 and UNED-UV9)
and their corresponding mixed runs (UNED-UV10-12 for the UNED-UV1, UNED-
UV13-15 for UNED-UV2, and so on). We have improved the precision values at 10
and at 20 with the mixed runs, i.e. the UNED-UV11-Feedback (Prec@10 0.3914 and
Prec@20 0.3629) improves its basic textual run UNED-UV1 (Prec@10 0.3914 and
Prec@20 0.3564). The same improvement can be observed for the other mixed runs
being compared with their corresponding textual runs. This result points out that
visual algorithms can improve the textual result lists by back forward to the end of the
list non relevant images retrieved by the textual module. However, MAP values are
still lower than their corresponding textual runs. This could be due to the fact that
more query images would be needed to get better results for higher precision
measures (P@30, P@40 and so on), improving in that way the medium of the
precision values (MAP).


5 Concluding Remarks and Future Work

Our best result is for the textual modality and it is at the position 34th, at the first 25%
of the best results of the contest; and, our best result for the mixed modality is at the
51th position, at the first 60% of the global contest. Most of our runs in
ImageCLEF10 are above the average for its own modality. These results mean that
our main algorithms for textual and visual modules have got good marks, and they
can be tuned to improve the current results.
   Regarding multilinguality, the multilingual run it is our best (multilingual query
launched to the multilingual index). It defeats the runs using monolingual queries
(also on multilingual index). When using monolingual indexes and merging the
results lists according to the query, only a slightly difference it is obtained (MAP
value 0.1927 > 0. 1865 for UNED_UV9). It is early to conclude about, but the effort
in preprocessing has to be taken into account to it.
   The best result for mixed runs has been obtained with the logistic regression
relevance feedback algorithm (UNED-UV11 at position 51), followed by the query
expansion and the automatic one. Our new algorithms (logistic regression relevance
feedback and query expansion) have markedly improved the results in comparison
with the automatic algorithm used in previous editions. It is also important to notice
that the best results of the contest are also achieved with a feedback algorithm. This
reinforces our idea that the feedback algorithms are the right track to maintain in our
future research lines.
Acknowledgments. This work has been partially supported by projects TIN2007-
67407-C03-03, TIN2007-67587 and TEC2009-12980 from Spanish government.


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