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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Deep Embedding-based Multimodal Matching for News Articles: Exploring the Efects of Transfer Learning &amp; Data Augmentation</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Martin Ludwig Zehetner</string-name>
          <email>m.zehetner@tu-berlin.de</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Mohamed Amine Dhiab</string-name>
          <email>m.dhiab@campus.tu-berlin.de</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Technische Universität Berlin</institution>
          ,
          <addr-line>Berlin</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Technische Universität Berlin</institution>
          ,
          <addr-line>Berlin</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2021</year>
      </pub-date>
      <fpage>13</fpage>
      <lpage>15</lpage>
      <abstract>
        <p>Choosing the right combination of news article image and title is critical for attracting new users and converting latent interest into clicks. In the context of the MediaEval 2021 NewsImages Challenge, we therefore investigated the underlying multimodal matching problem between images and titles of news articles by employing deep embedding-based models to map and match images and text in the same semantic space. Additionally we explored the impact of transfer learning and paraphrasing-based data augmentation schemes on the task performance. We observed a clear improvement in performance using transfer learning approaches, but no consistent improvement using the data augmentation technique we selected. Our best model achieved a mean recall@100 of 0.3488.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>INTRODUCTION</title>
      <p>Online news articles commonly try to convey content in a
distinctive and direct manner through combinations of expressive titles
and images. Understanding the relationships between these news
images and texts, e.g. news headlines, can therefore help to provide
insight into a wide variety of diferent tasks in the news domain.</p>
      <p>
        In this sense, the MediaEval 2021 NewsImages Re-Matching Task
aims to advance this investigation by setting a task to re-match
decoupled real-world news articles with the images used in said
articles [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. In particular, given a news article the corresponding
article image is to be selected from the set of all images.
      </p>
      <p>
        We attempted to further the understanding of these
relationships and solve the task given by using multimodal embeddings,
specifically embeddings that map images and texts into the same
semantic “news” vector space. These embeddings are generated
using variations of the Self-Attention Embeddings for Image-Text
Matching (SAEM) model framework [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] and are intended to enable
the computation of semantic similarity, with regard to the “news”
domain, between texts and images using basic similarity metrics.
In this context, we placed a special emphasis on investigating the
efects of a transfer learning scheme, using information exploited
from image caption data sets, and augmenting the given text data
by applying a paraphrase-based approach.
      </p>
    </sec>
    <sec id="sec-2">
      <title>RELATED WORK</title>
      <p>
        Matching media objects of diferent modalities, e.g. text and images,
is essential for various multimedia tasks. Learning a common space
into which text and image feature vectors can be embedded and
then compared in is a typical approach for such tasks [
        <xref ref-type="bibr" rid="ref2 ref7">2, 7</xref>
        ].
      </p>
    </sec>
    <sec id="sec-3">
      <title>APPROACH</title>
    </sec>
    <sec id="sec-4">
      <title>Deep Embedding-based Multimodal</title>
    </sec>
    <sec id="sec-5">
      <title>Matching using SAEM</title>
      <p>
        A central component of our approach is the generation of directly
comparable text and image embeddings using variations of SAEM
models. We chose to use the SAEM model framework as it allows
easy customization of the input image feature sources and achieved
good results in other cross-media retrieval tasks on the Flickr30k
and MS-COCO image captioning data sets [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ].
      </p>
      <p>
        We decided to only use the images and article titles from the
MediaEval data set [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] in our SAEM variations, due to superior
performance in initial tests and restricted translation and paraphrasing
resources. For the generation of image feature vectors representing
the salient image regions, we used a bottom-up attention
mechanism [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] consisting of a Faster R-CNN with ResNet-101 trained on
Visual Genomes [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. We set the dimensions of these feature
vectors to (36, 2048). In addition we used the WordPiece tokenizer [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]
to process the article titles to generate the initial text input.
      </p>
      <p>
        It is important to point out that unlike in the introduction of
the SAEM model framework [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ], in which the focus was only on
matching semantically identical images and texts, the focus in our
approach lays rather on the somewhat more abstract task of
mapping the similarity of image and text elements in the semantics of
the online news article context, i.e. which image would be selected
to match a given article title. This is to be achieved by means of
training and fine-tuning on the provided MediaEval image-title
pairs [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. Concurrently, the training process is used to optimize
the hyperparameters, e.g. learning parameters, the use of transfer
learning and the use of data augmentation. The trained models are
then used to compute the images which best match the article titles
based on the cosine similarity of the corresponding embeddings.
3.2
      </p>
    </sec>
    <sec id="sec-6">
      <title>Transfer Learning</title>
      <p>
        Transfer learning broadly describes the use of knowledge learned
in one scenario to improve the training process or results in
another [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Among the most commonly used strategies in the neural
network field are various approaches using pre-trained models [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>In our approach, due to the relatively small size of the MediaEval
data set, we decided to investigate and try to exploit the efect of
a direct pre-trained model strategy in our task scenario. To this
end, we first train our SAEM variants on either the Flick30K or the
MS-COCO data set. We then fine-tune the SAEM models using the
best versions of the pre-trained models as the initial model states
and then train the models using the news images and titles.
3.3</p>
    </sec>
    <sec id="sec-7">
      <title>Data Preparation &amp; Augmentation</title>
      <p>
        In general, performance of neural networks can be influenced
heavily by the size and quality of the training data sets [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]. In many
real world tasks, relatively few data points are available for the
training process, such as in our MediaEval task. A potential
solution is data augmentation, i.e. the generation of new data points
to increase training data diversity [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. Therefore, we investigated
the efects of an augmentation approach consisting of generating a
new paraphrased title for each article title in the training set, where
the image is mapped to both titles. By doing so, we doubled the
amount of training data.
4
4.1
      </p>
    </sec>
    <sec id="sec-8">
      <title>EXPERIMENT</title>
    </sec>
    <sec id="sec-9">
      <title>Data Pre-Processing &amp; Augmentation</title>
      <p>
        Initial image feature vectors are generated following the procedure
practiced in the SCAN [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] project. As the first step of text
preprocessing, we translate the article titles into english using DeepL.
For the text augmentation steps, we then used Quillbot to generate
paraphrases for the article titles using the default mode with the
highest possible abstraction level for the generated phrases [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
4.2
      </p>
    </sec>
    <sec id="sec-10">
      <title>Model Implementation</title>
      <p>
        For the selected models we used the Adam [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] optimizer with an
initial learning rate of 0.001 and a batch size of 64 while training.
During pre-training, a decay rate of 0.1 was applied after every 10
epochs, but when training on the MediaEval data the decay was
applied only after every 15 epochs. The dimension of the internal
word embedding was set to 300 and the dimension of the final
multimodal embedding was fixed to 256.
4.3
      </p>
    </sec>
    <sec id="sec-11">
      <title>Experiment Protocol</title>
      <p>
        Training &amp; Evaluation of pre-trained Models. The training
described below is performed separately for Flickr30K and MS-COCO.
Firstly, the image-annotation pairs are split according to the public
split [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]. The SAEM models are then trained for 30 epochs and
after each epoch the ratio of recommendations in which at least one
relevant image was ranked among the top 1, 5 and 10 is determined
M.L. Zehetner, M.A. Dhiab
0.07050
0.08512
0.1159
0.1003
on the validation data. Afterwards, the model with the highest mean
between these 3 metrics is selected as the best pre-trained model.
In our experiment this best model was trained on MS-COCO.
      </p>
      <p>
        Training &amp; Evaluation of MediaEval Models. The second phase
of the experiment focuses on the comparison of the performance
of the SAEM models with diferent configuration combinations.
The “Initial Model State”  and the “Textual Input Type”  can
be seen as variables of the configurations.  can represent the
initialization of the SAEM model randomly or based on the best
pre-trained model.  can represent the use of only translated article
titles or the use of translated titles together with paraphrased titles.
The data is then split, with the first two batches of the MediaEval
data set representing the training data and the third batch used
as validation data [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. Afterwards, for each of the possible four
(,  ) combinations, the following steps are performed. First the
input data is augmented and processed according to the current  .
Then the model is initialized according to the current . Thereafter,
the SAEM model is trained for 50 epochs using the pre-processed
training data. Subsequently, the best models of the current
configurations are selected by calculating @ for  = 1, ..., 100 for
the matchings, according to cosine similarity, of the trained model
on the validation data set. The four submission models represent
the best performing models in each configuration.
5
      </p>
    </sec>
    <sec id="sec-12">
      <title>RESULTS &amp; FUTURE WORK</title>
      <p>
        The performance of our four submitted models on the MediaEval
test set [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] can be seen in Table 1. While no massive performance
diferences are present, clear performance gaps can be observed
nevertheless. Our best performing variant is pre-trained but does
not use the paraphrase-based data augmentation method,
reflecting the general observed tendencies. As such, consistently better
performance is observed for the pre-trained variants, while the use
of our data augmentation approach shows no consistent
performance improvements. Concluding, we recognize that our results
indicate that exploiting learned information from similar task
domains through transfer learning can be highly beneficial in news
re-matching scenarios with small amounts of training data, such as
the considered MediaEval 2021 NewsImages task.
      </p>
      <p>In this sense, our observations suggest that further investigation
regarding the exploitation of externally learned information may
be worthwhile. In addition to more detailed analysis regarding the
influence of information learned in less or more related tasks and
with less or more available data, investigating the explicit addition
of available contextual information, such as knowledge related to
identities or locations, could allow for further valuable insights.</p>
    </sec>
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