Organizations: Department of Computer Science, University of Bari Aldo Moro, Italy · Hasso Plattner Institute, University of Potsdam, Germany · ZBW - Leibniz Information Centre for Economics, University of Kiel, Germany
Discovering and disambiguating entities from multimodal and heterogeneous data is a key challenge in discovery science, where relevant knowledge is often implicit and distributed across modalities. We present KARAMEL, a framework for multimodal entity linking (MEL) - the task of aligning visual and textual mentions to entities in a knowledge base - in the cultural heritage domain. Unlike prior vision-language models that primarily rely on surface-level multimodal alignment, our approach incorporates sociohistorical and contextual knowledge through a knowledge-aware architecture that fuses a vision-language encoder with a heterogeneous graph neural network. This design enables contextual reasoning over complex relational structures and supports robust entity disambiguation under ambiguous or underspecified evidence. To benchmark multimodal discovery in this setting, we introduce WikiMuSA (Wikidata-based Multimodal Semantic data for Art), a new dataset that links artworks to Wikidata entities via images, textual descriptions, and structured contextual knowledge. Experimental results show that KARAMEL surpasses strong baselines, particularly on implicit or abstract mentions, while ablation studies highlight the critical role of domain-specific, structured context in learning expressive representations. While instantiated in the cultural heritage domain, KARAMEL addresses a general knowledge discovery problem and applies to other scientific settings involving multimodal observations and heterogeneous background knowledge. Both the dataset and source code are made publicly available.
Figures & tables
Figure 1: Comparison between the standard multimodal entity linking setting (a), where entity mentions are explicitly highlighted in the text, and our proposed setting (b), where mentions must be inferred from raw Wikipedia articles without predefined annotations.
Figure 2: Logical schema of W iki M u SA . Each artwork is associated with metadata, including author, genre, and movement. Depicted entities are linked through enriched, contextual relationships that enhance expressiveness and graph connectivity.
Figure 3: Architecture of KARAMEL. The image-text cross-encoder and the GNN encoder are jointly trained to extract complementary information from artworks and depicted entities. The cross-modal ranker is then trained to rank candidate entities effectively for a given input mention.
Model
R@1
R@10
R@50
R@100
MAP
MRR
BERT [ 43 ]
2.33 ( ± 0.88)
10.56 ( ± 2.53)
24.52 ( ± 3.61)
32.41 ( ± 3.2)
5.93 ( ± 1.53)
11.94 ( ± 2.36)
CLIP [ 41 ]
0.24 ( ± 0.08)
2.68 ( ± 0.68)
13.12 ( ± 2.9)
22.57 ( ± 4.12)
1.25 ( ± 0.09)
3.0 ( ± 0.19)
ViLT [ 47 ]
0.62 ( ± 0.1)
5.01 ( ± 0.58)
16.4 ( ± 0.51)
23.71 ( ± 1.27)
1.08 ( ± 0.22)
2.43 ( ± 0.5)
MIMIC [ 12 ]
27.22 ( ± 1.19)
60.93 ( ± 1.32)
77.26 ( ± 0.75)
82.52 ( ± 0.62)
47.0 ( ± 1.66)
65.72 ( ± 1.88)
KARAMEL ( Ours )
27.26 ( ± 0.47)
62.31 ( ± 0.57)
78.48 ( ± 0.67)
83.65 ( ± 0.45)
48.45 ( ± 0.7)
66.88 ( ± 0.51)
Table 1: Ranking metrics for the baselines and KARAMEL. Each cell reports the mean and standard deviation (in parentheses). All metrics are expressed in the range [0, 100]. The best performance per metric is shown in bold .
Model
R@1
R@10
R@50
R@100
MAP
MRR
MIMIC [ 12 ]
50.07 ( ± 1.98)
83.0 ( ± 1.47)
91.76 ( ± 1.28)
94.73 ( ± 0.91)
70.08 ( ± 1.96)
80.44 ( ± 1.67)
KARAMEL
51.07 ( ± 1.62)
82.91 ( ± 2.35)
91.09 ( ± 2.09)
94.25 ( ± 1.7)
71.34 ( ± 1.92)
81.34 ( ± 1.57)
Table 2: Ranking metrics for MIMIC and KARAMEL on MELArt [ 10 ] . Each cell reports the mean and standard deviation (in parentheses). All metrics are expressed in the range [0, 100]. The best performance per metric is shown in bold .
Figure 4: Average rank difference of KARAMEL on MIMIC [ 12 ] . Bars below the x-axis indicate improved ranking of KARAMEL. Numbers within each bar denote the number of ( artwork , depicted entity ) pairs supporting the corresponding feature. Blue bars denote statistically significant effects, whereas red bars indicate non-significant effects.
Image & Text
MIMIC
KARAMEL
1
Oar. water-borne propulsion
Polyphemus giant son of Poseidon.
2
Polyphemus . giant son of Poseidon.
Odysseus . Greek king of Ithaca.
The artwork “Odysseus and Polyphemus” represents a pivotal moment from Homer’s epic poem, where Odysseus taunts the one-eyed Cyclops Polyphemus as he prepares to hurl a rock at the escaping boat of Odysseus and his crew.
3
wind wave . waves that occur on water
oar . water-borne propulsion
4
cyclops . giant in Greek mythology.
cyclops . giant in Greek mythology.
Ground Truth: Polyphemus . giant son of Poseidon. Odysseus . Greek king of Ithaca.
Table 3: Top-4 ranking comparison for “ Odysseus and Polyphemus ” ( Q20537891 ), a painting by Arnold Böcklin (1896), between KARAMEL and MIMIC [ 12 ] . Ground truth entities are highlighted.
Full Graph
Encoding
R@10
MAP
MRR
✗
Multimodal
60.82 ( ± 1.42)
47.11 ( ± 1.80)
65.44 ( ± 2.17)
✗
Hybrid
60.44 ( ± 2.32)
46.96 ( ± 3.39)
65.64 ( ± 3.55)
✗
Textual
61.42 ( ± 1.92)
47.87 ( ± 2.72)
66.74( ± 3.05)
✓
Multimodal
62.05 ( ± 0.38)
48.28 ( ± 0.83)
67.53 ( ± 1.09)
✓
Hybrid
61.87 ( ± 0.62)
48.81 ( ± 0.69)
67.93 ( ± 1.04)
✓
Textual
62.31 ( ± 0.57)
48.45 ( ± 0.70)
66.88 ( ± 0.51)
Table 4: Ablation study on the effect of both contextual factors (i.e., Full Graph) and node feature encoding variations (i.e., Textual, Hybrid, and Multimodal). Numbers in bold indicate the best results.
Appendix figures & tables4 assets
Supplementary material from the paper’s appendix.
Appendix
Figure 5: Distribution of artwork Wikipedia articles ( x -axis) by original language ( y -axis).
Rouge1
Rouge2
RougeL
mean
0.745735
0.381481
0.530465
std
0.158000
0.138832
0.134143
Appendix
Table 5: ROUGE precision metrics
Figure 6: Length in words of the original articles and their summaries. The color represents the ROUGE-1 precision for each article-summary pair.
Figure 7: Distribution of ROUGE precision between the summaries and the full articles.
The University of New South Wales Sydney, Australia · Shanghai Jiao Tong University Shanghai, China · University of Technology Sydney Sydney, Australia