=Paper= {{Paper |id=Vol-1586/ldmc4 |storemode=property |title=Can You Judge a Music Album by its Cover? |pdfUrl=https://ceur-ws.org/Vol-1586/ldmc4.pdf |volume=Vol-1586 |authors=Petar Petrovski,Anna Lisa Gentile |dblpUrl=https://dblp.org/rec/conf/esws/PetrovskiG16 }} ==Can You Judge a Music Album by its Cover?== https://ceur-ws.org/Vol-1586/ldmc4.pdf
    Can you judge a music album by its cover?

                      Petar Petrovski1 , Anna Lisa Gentile1

         Data and Web Science Group, University of Mannheim, Germany
                {petar,annalisa}@informatik.uni-mannheim.de



      Abstract. In this work we explore the potential role of music album
      cover arts for the task of predicting the overall rating of music albums
      and we investigate if one can judge a music album by its cover alone.
      We present the results of our participation to the Linked Data Mining
      Challenge at the Know@LOD 2016 Workshop, which suggest that the
      the cover album alone might not be sufficient for the rating prediction
      task.


Keywords: Classification, Image Embeddings, DBpedia


1   Introduction

Music is not just about the music. Granted, the listening experience is certainly
the most essential element, but one can not ignore the role of cover art in making
a brilliant album. In the literature several methods have been proposed to repre-
sent music albums not only with information directly extracted from the musical
content [2], but also e.g. from entities and relations extracted from unstructured
text sources [1], user interaction evidence [6]. With respect to the role of visual
clues, Lı̄beks and Turnbull [5] have investigated how the image of an artist can
play a role in how we judge a music album. They proposed a method to predict
music genre tags based on image analysis, with the purpose to assess similarity
amongst artists to inform the music discovery process. In our work we investi-
gate if there is any correlation between certain patterns in the album cover and
the overall rating for the music album as a whole. Our question therefore is “can
one judge a music album by its cover, after all?”.
    We present results of our participation1 to the Linked Data Mining Chal-
lenge2 at the Know@LOD 2016 Workshop. The task of the challenge consists
of predicting the rating of music albums, exploiting any available data from
the Linked Open Data cloud. The dataset of the challenge is obtained from
Metacritic3 , which collects critics’ reviews on musical works. Specifically, the
organisers sampled a number of musical albums from the website and labeled
1
  Submission Petar P. Grd at http://ldmc.informatik.uni-mannheim.de/
2
  http://knowalod2016.informatik.uni-mannheim.de/en/linked-data-mining-
  challenge/
3
  http://www.metacritic.com/
each album as “good” when the critics’ score for it is greater than 80 and “bad”
when lesser than 60.
    To answer our question, we learn a SVM model that classifies music albums
either as “good” or “bad” and we train the model only using the cover art of each
album. The feature extraction from the cover art is based on image embeddings.


2     Classification of music albums
Our proposed approach for album classification consists of three main steps.
Given a collection of music albums, we first obtain the image of their cover art.
Then, using off-the-shelf tools we obtain a feature vector representation of the
images. We then learn a classifier to label each album as “good” or “bad”, only
exploiting the feature space obtained from its cover art. Figure 1 depicts the
proposed pipeline.




           Fig. 1: Pipeline for the classification of music albums using their cover art.




2.1    Dataset
In this work we use the Know@LOD 2016 challenge dataset. It consists of 1,600
music albums. Each item provides:
 – album name
 – artist name
 – album release date
 – DBpedia4 URI for the album
 – the classification of the album as “good” or “bad”.
   The organisers split the dataset as 80% (1,280 instances) for training, and
20% (320 instances) for the test.
In our experiment we deliberately only want to exploit the cover art of the
albums, therefore we only use only the DBpedia URIs of the albums to obtain
their cover images. First, by using Rapidminer LOD extension [7], we retrieve
the dbp:cover5 property for each album. The property contains the path to the
4
    http://dbpedia.org
5
    The prefix dbp: stands for the namespace http://dbpedia.org/property/.
image of the cover art. Then, by using the Mediawiki API6 , we download all the
images.
    The resulting image set consists of 1558 images, with 2 images missing (the
path obtained from dbp:cover did not correspond to any Wikipedia resource).
    The dataset is available at https://github.com/petrovskip/know-lod2016, to-
gether with the extracted feature vectors and process used (explained in section
3).

2.2   Classification approach.
We learn a SVM model that classifies music albums either as “good” or “bad”.
Starting from our image set, we use image embeddings to obtain a feature space.

Feature set. We use the Caffe deep learning framework [3] to obtain image
embeddings. Together with deep learning algorithms, Caffe also provides a col-
lection of reference models, which are ready to use for certain labelling tasks.
Specifically, we used the bvlc model7 by Krizhevsky et al. [4]. It consists of a
neural network of five convolutional layers, and three fully-connected layers. The
model has been trained on the ImageNet collection, a dataset of 1.2 million la-
belled images from the ILSVRC2012 challenge8 . Each layer of the model provides
a representation of the image features, with associated weights. The last layer
is the one that outputs the labels for each image. This model outputs as labels
1000 different classes, according to the training ImageNet collection. Since we
are not interested in these 1000 labels, but we only want to classify images as
“good” or “bad”, we classify our image set with this model, but we only use the
output layer before the last (the second fully-connected layer), from which we
obtain (i) images features and their weighting. The resulting feature vector has
a length of 4,096. These features represent visual components of the images, e.g.
colours, shapes etc.

Learning process We use all obtained features (without any fine-tuning) to train
the C-SVM classifier (a wrapper implementation of libSVM classifier on Rapid-
miner) with a linear kernel and the default parameters.


3     Experiment
We evaluated our approach using 10-fold cross validation on the training set and
we obtained an accuracy of 58.03%. The resulting confusion matrix is presented
in Table 1. The accuracy of the test set reported by the challenge system is of
60.3125%.
   The low accuracy of our approach seems to suggest that the image alone is not
a good predictor of the overall rating of the musical album. Nevertheless it would
6
  https://www.mediawiki.org/wiki/API:Main page
7
  bvlc reference caffenet from caffe.berkeleyvision.org
8
  http://image-net.org/challenges/LSVRC/2012/
                               Table 1: Confusion matrix.

                              true good true bad class precision
                   pred. good    385       282       57.72%
                   pred. bad     254       356       58.36%
                  class recall 60.25% 55.80%




be interesting to investigate if fine-tuning of the features or the combination pf
other factors could lead to better results.


4    Conclusion

This paper presents our submission to the Linked Data Mining Challenge at
the Know@LOD 2016 workshop. We proposed an approach that classifies music
albums into “good” or “bad” based solely on their cover art. We trained a SVM
classifier with the feature vector calculated from the album’s cover art to solve
the prediction problem of music album classification. While our approach has
some interesting results, our experiment hints that only using album covers as
features is not the best fit for the task of the challenge.


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