News

Octave Convolution & Cyclical Visual Grounding (June 2019)

Two new technical reports are on arXiv:

Y. Chen, H. Fan, B. Xu, Z. Yan, Y. Kalantidis, M. Rohrbach, Z. Yan, Y. Shuicheng, J. Feng. Drop an Octave: Reducing Spatial Redundancy in Convolutional Neural Networks with Octave Convolution. arXiv:1904.05049, 2019. [Project Page]
C.Y. Ma, Y. Kalantidis, G. AlRegib, P. Vajda, M. Rohrbach, Z. Kira. Learning to Generate Grounded Image Captions without Localization Supervision. arXiv:1906.00283, 2019. [MXNet code]

Numerous implementations of OctConv can be found on Papers With Code.

Papers accepted at CVPR 2019 (February 2019)

Delighted to announce that four papers were accepted at CVPR 2019!

Computer Vision for Global Challenges Workshop @ CVPR 2019 (January 2019)

Our first Workshop on Computer vision for Global Challenges (CV4GC) was accepted at CVPR this year! Really excited about organizing an initiative to bring the computer vision community closer to socially impactful tasks, datasets and applications for the whole world. Check out the CV4GC website!

Paper accepted in TPAMI (January 2019)

Our paper Focal Visual-Text Attention for Memex Question Answering was accepted for publication at the IEEE Transactions on Pattern Analysis and Machine Inteligence (impact factor: 9.455). It introduces our MemexQA Dataset, the first publicly available multimodal question answering dataset consisting of real personal photo albums.

Large-scale Visual Relationship Detection @ AAAI 2019 (November 2018)

Our paper Large-scale Visual Relationship Detection was accepted at the Thirty-Third AAAI Conference on Artificial Intelligence (AAAI 2019, acceptance rate 16.2%).
[Update Feb 2019]: Code is now on github.

Double Attention Networks @ NIPS 2018 (September 2018)

Our paper A^2-Nets: Double Attention Networks was accepted at NIPS 2018. See you in Montreal! Work with awesome collaborators from the National University of Singapore.

Multi-Fiber Networks @ ECCV 2018 (July 2018)

Our paper Multi-Fiber Networks for Video Recognition was accepted at the European Conference on Computer Vision (ECCV) 2018. Work with awesome collaborators from the National University of Singapore. Code on GitHub.

Do Silhouettes Dream? (May 2017)

Our interactive art installation entitled Do Silhouettes Dream? will be on display from July 26th till August 2nd 2017 at the ArtScience Museum in Singapore. More information at this page. You may watch a short interview with Cheng and me here.

Similarity Search at Flickr (March 2017)

Our work on visual similarity search over the whole Flickr corpus just launched! Try it yourselves by clicking on the magnifying glass icon at the top right corner of any photopage! Story covered in The Verge, Engadget, Petapixel, Digital Trends and Venture Beat.

New chapter: Facebook Research (February 2017)

After two amazing years at Yahoo Research, joined the Computer Vision Group at Facebook Research in Menlo Park.

Best paper at LSCVS Workshop in NIPS 2016 (December 2016)

Our paper "Tag Prediction in Flickr: A view from the darkroom" on large scale image classification with noisy training data received the best paper award at the 1st Workshop on Large Scale Computer Vision Systems at NIPS 2016.

Paper accepted at CHI 2017 (December 2016)

Our paper "Multimodal Classification of Moderated Online Pro-Eating Disorder Content" was accepted at the ACM CHI 2017 conference (25% acceptance rate).

Guest Lecturer at Stanford CS-131 (October 2016)

Will be a guest lecturer at Fei-Fei's and Juan Carlos' CS 131 Computer Vision: Foundations and Applications course at Stanford during the 2016-2017 Fall Semester.

Paper accepted at WSDM 2017 (October 2016)

Our paper "Delving Deep into Personal Photo and Video Search" was accepted for publication at WSDM 2017 (16% acceptance rate).

About Me

Grew up and lived in Greece until 2015 with brief breaks in Sweden, Spain and the United States. Lived in San Francisco from 2015 till 2017 and currently in Oakland.

Got my PhD in late 2014 from the National Technical University of Athens under the supervision of Prof. Stefanos Kollias and Yannis Avrithis, working closely with my research brother Giorgos Tolias.

The large-scale visual similarity search work of my PhD came to a nice closure while a researcher at Yahoo Research, as it was applied on a trully web scale powering the visual search feature on Flickr. At the same time, my interests expanded towards modeling of vision and language and collaborated with Stanford on the Visual Genome project.

Currently conducting research and development on video understanding, temporal segmentation, learning image & video representations, multi-modal classification and large-scale vision and language.

Contact Details

ykalant(at)image.ntua.gr yannisk(at)fb.com

One Page Resume Complete CV

Development projects and Demos

LOPQ Resources: Project page and code, Python code at Yahoo GitHub.
Code for the Crow features at the Yahoo GitHub.
Online demo for VIRaL: Visual Image Retrieval and Localization.

Selected Publications

Full list at my Google Scholar profile.

2019

C.Y. Ma, Y. Kalantidis, G. AlRegib, P. Vajda, M. Rohrbach, Z. Kira. Learning to Generate Grounded Image Captions without Localization Supervision. arXiv:1906.00283, 2019. [Project Page]
Y. Chen, H. Fan, B. Xu, Z. Yan, Y. Kalantidis, M. Rohrbach, Z. Yan, Y. Shuicheng, J. Feng. Drop an Octave: Reducing Spatial Redundancy in Convolutional Neural Networks with Octave Convolution. arXiv:1904.05049, 2019. [Numerous Opensource Implementations].
Y. Chen, M. Rohrbach, Z. Yan, Y. Shuicheng, J. Feng, Y. Kalantidis. Graph-Based Global Reasoning Networks. In Computer Vision and Pattern recognition (CVPR), 2019.
L. Zhou, Y. Kalantidis, X. Chen, J. Corso, M. Rohrbach. Grounded Video Description. In Computer Vision and Pattern recognition (CVPR), 2019. [ActivityNet-Entities dataset on github]
B. Xiong, Y. Kalantidis, D. Ghadiyaram, K. Grauman. Less is More: Learning Highlight Detection from Video Duration.. In Computer Vision and Pattern recognition (CVPR), 2019.
Z. Shou, Z. Yan, Y. Kalantidis, L. Sevilla-Lara, M. Rohrbach, X. Lin, S.-F. Chang. DMC-Net: Generating Discriminative Motion Cues for Fast Compressed Video Action Recognition.. In Computer Vision and Pattern recognition (CVPR), 2019.
L. Jiang, L. Cao, Y.~Kalantidis, S. Farfade and A. Hauptmann. Focal Visual-Text Attention for Memex Question Answering. In IEEE Transactions on Pattern Analysis and Machine Intelligence (PAMI), 2019.
J. Zhang, Y. Kalantidis, M. Rohrbach, M. Paluri A. Elgammal, M. Elhoseiny. Large-Scale Visual Relationship Understanding. In the thirty-third AAAI Conference on Artificial Intelligence (AAAI), 2019. [code on github]

2018

Y. Chen, Y. Kalantidis, J. Li, Y. Shuicheng, J. Feng. A^2-Nets: Double Attention Networks. In Neural Information Processing Systems (NeurIPS), 2018.
Y. Chen, Y. Kalantidis, J. Li, Y. Shuicheng, J. Feng. Multi-Fiber Networks for Video Recognition. In European Conference on Computer Vision (ECCV), 2018. [code]

2017

R. Krishna, Y. Zhu, O. Groth, J. Johnson, K. Hata, J. Kravitz, S. Chen, Y. Kalantidis, L.-J. Li, D.A. Shamma, M. Bernstein and L. Fei-Fei. Visual Genome: Connecting Language and Vision Using Crowdsourced Dense Image Annotations. In International Journal of Computer Vision (IJCV), 2017.
L. Jiang, L. Cao, Y. Kalantidis, S. Farfade and A. Hauptmann. MemexQA: Visual Memex Question Answering. arXiv:1708.01336, 2017.
L. Jiang, Y. Kalantidis, L. Cao, S. Farfade, J. Tang and A. Hauptmann. Delving Deep into Personal Photo and Video Search. In Web Search and Data Mining (WSDM), 2017.
S. Chancellor, Y. Kalantidis, J. A. Pater, M. De Choudhury and D. A. Shamma. Multimodal Classification of Moderated Online Pro-Eating Disorder Content. In ACM CHI Conference on Human Factors in Computing Systems (CHI), 2017.

2016

P. Garrigues, S. Farfade, H. Izadinia, Kofi Boakye and Y. Kalantidis. Tag Prediction in Flickr: A view from the darkroom. (Best paper award) In Large Scale Computer Vision systems Workshop at NeurIPS, 2016.
Y. Kalantidis, C. Mellina and S. Osindero. Cross-dimensional Weighting for Aggregated Deep Convolutional Features. In Web-scale Vision and Social Media (VSM) Workshop, ECCV, 2016. [code]
Y. Kalantidis, L. Kennedy, H. Nguyen, C. Mellina and D.A. Shamma. LOH and behold: Web-scale visual search, recommendation and clustering using Locally Optimized Hashing. In Web-scale Vision and Social Media (VSM) Workshop, ECCV, 2016.
Y. Kalantidis, A. Farahat, L. Kennedy, R. Baeza-Yates and D.A. Shamma. Visual Congruent Ads for Image Search. In International Conference on Pattern Recognition (ICPR), 2016.

2015

Y. Avrithis, Y. Kalantidis, E. Anagnostopoulos and I. Z. Emiris. Web-scale image clustering revisited. In International Conference on Computer Vision (oral) (ICCV), 2015.

2014

Y. Kalantidis and Y. Avrithis. Locally Optimized Product Quantization for Approximate Nearest Neighbor Search. In Computer Vision and Pattern Recognition (CVPR), 2014. [code]
G. Tolias, Y. Kalantidis, and Y. Avrithis. Towards large-scale geometry indexing by feature selection. Computer Vision and Image Understanding (CVIU), 2014.

2011 - 2013

Y. Kalantidis, L. Kennedy and L.-J. Li. Getting the Look: Clothing Recognition and Segmentation for Automatic Clothing Suggestions in Everyday Photos. In International Conference on Multimedia Retrieval (Oral paper) (ICMR), 2013.
Y. Avrithis and Y. Kalantidis. Approximate gaussian mixtures for large scale vocabularies. In European Conference on Computer Vision (ECCV), 2012.
G. Tolias, Y. Kalantidis, and Y. Avrithis. Symcity: Feature selection by symmetry for large scale image retrieval. In ACM Multimedia (Oral paper) (ACM MM 2012), 2012.
Y. Avrithis, Y. Kalantidis, G. Tolias, and E. Spyrou. Retrieving landmark and non-landmark images from community photo collections. In ACM Multimedia (Oral paper) (ACM MM 2010), 2010.
Y. Avrithis, G. Tolias, and Y. Kalantidis. Feature map hashing: Sub-linear indexing of appearance and global geometry. In ACM Multimedia (Oral paper) (ACM MM 2010), 2010.
Y. Kalantidis, LG. Pueyo, M. Trevisiol, R. van Zwol, and Y. Avrithis. Scalable triangulation-based logo recognition. In International Conference on Multimedia Retrieval (ICMR), 2011.
Y. Kalantidis, G. Tolias, Y. Avrithis, M. Phinikettos, E. Spyrou, P. Mylonas, and S. Kollias. Viral: Visual image retrieval and localization. Multimedia Tools and Applications (MTAP), 2011.

Photography

Primarily shoot 35mm film and upload selected works on Flickr and recently also on Instagram.

Ignore the boat

As tide goes by

Strolling through a rainy day

Pretty Lighthouse, Pretty Flame - Burning Man 2016

What is hip?

Stepping Stone

Double exposure, Bolinas, CA

(Street) music pays

Grandma turns 100

Freestyle acro

No parking any time. Yes jazzing any time

Paperback

Family on hammock

Archer

Favela superstar

One Way

Film

Have shot two films, an award winning short and a feature length documentary screened at the Athens International Film Festival (Νύχτες Πρεμιέρας) in 2015. Both are available online.

Love is Blind (2008)

Short film (8', black and white)
Official Selection:
- 11th International Panorama of Independent Film and Video Creators (Patra, Greece 2009)
- Athens Fantastic Film Festival 2009 (Ilioupoli, Athens, Greece 2009)
Awards:
- Audience Choice Award (Athens Fantastic Film Festival 2009, Ilioupoli, Greece)
- Online Fantastic Film Audience Choice Award (2010, www.bigbang.gr)
Blind Crossing (2015)

Documentary Feature Film (57', color)

Visit the IMDB page.
Official Selection:
- Athens International Film Festival (Athens, Greece, 2015)
- Chalkida DocFest (Chalikda, Greece, 2015)

Interactive art

Do Silhouettes Dream?

...is an interactive art installation.

It will be on display from July 26th till August 2nd 2017 at the ArtScience Museum in Singapore.

"Do Silhouettes Dream?" aims to place fascinating results of cutting-edge artificial intelligence in a public embodied experience. As participants stand in front of a projection screen, their silhouettes create an area of hallucination that changes with their movement. Hallucinations may vary; some are ``dreams'', transporting the area covered by the silhouette to past or future times. Others escape reality and either alter the visual artistic style or form ``deep dreams'', i.e. hallucinations created through a feedback loop on artificial deep neural networks.

More information can be found in this short paper, while code to reproduce the installation is available on Github.

The artwork was accepted in the Art Track of the Creativity and Cognition 2017 conference as part of the Microbites of Innovation showcase. Co-created with Clayton Mellina and Cheng Xu.

You may watch a short interview with Cheng and me here.

Some photos and videos here!

(*) Figures above feature a Creative Commons image courtesy of Mike Cartmell on Flickr and a frame from Singapore City Day-Night Time lapse, used with permission.

Music

Disturbing Music

In 2014, curated a web-radio series dedicated to experimental and improvisational music.

All playlist can be found in the Disturbing Music Blog.

Bands and stuff

Keyboard/piano player, lover of improvisational music (aka lazy to study). Have played with many bands [citation needed] spanning different genres like post-progressive Greek rock with Amorfi Plektani, pop-rock with λaternative, jazz with the Silly Walks and improvisational folk-rock with Dimitris K. Karras.