Visual-based social media are growing exponentially and have become an integrated part of the customer engagement strategy of many brands. Prior work points to the textual message content as a driver of customer engagement behavior. So far, little is known about the impact of visual message content, specifically visual emotional and informative appeals. We extract emotional and informative appeals from Instagram posts using machine learning models and use a Negative Binomial model to explain customer engagement. We test our model on 46.9 K Instagram posts from 59 brands in six sectors. Our results show that visual emotional and informative appeals encoded in brand-generated content influence customer engagement in terms of likes and comments. Specifically, we demonstrate that positive high and negative low arousal images drive customer engagement. Informative appeals do not drive customer engagement with the exception of informative brand-related appeals. These findings help brand managers in developing an effective customer engagement strategy on visual social media.

Brand-related user posts on social networks are growing at a staggering rate, where users express their opinions about brands by sharing multimodal posts. However, while some posts become popular, others are ignored. In this paper, we present an approach for identifying what aspects of posts determine their popularity. We hypothesize that brandrelated posts may be popular due to several cues related to factual information, sentiment, vividness and entertainment parameters about the brand. We call the ensemble of cues engagement parameters. In our approach, we propose to use these parameters for predicting brand-related user post popularity. Experiments on a collection of fast food brand-related user posts crawled from Instagram show that: visual and textual features are complementary in predicting the popularity of a post; predicting popularity using our proposed engagement parameters is more accurate than predicting popularity directly from visual and textual features; and our proposed approach makes it possible to understand what drives post popularity in general as well as isolate the brand specific drivers.

An emerging trend in video event detection is to learn an event from a bank of concept detector scores. Different from existing work, which simply relies on a bank containing all available detectors, we propose in this paper an algorithm that learns from examples what concepts in a bank are most informative per event. We model finding this bank of informative concepts out of a large set of concept detectors as a rare event search. Our proposed approximate solution finds the optimal concept bank using a cross-entropy optimization. We study the behavior of video event detection based on a bank of informative concepts by performing three experiments on more than 1,000 hours of arbitrary internet video from the TRECVID multimedia event detection task. Starting from a concept bank of 1,346 detectors we show that 1.) some concept banks are more informative than others for specific events, 2.) event detection using an automatically obtained informative concept bank is more robust than using all available concepts, 3.) even for small amounts of training examples an informative concept bank outperforms a full bank and a bag-of-word event representation, and 4.) we show qualitatively that the informative concept banks make sense for the events of interest, without being programmed to do so. We conclude that for concept banks it pays to be informative.

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We aim to query web video for complex events using only a handful of video query examples, where the standard approach learns a ranker from hundreds of examples. We consider a semantic signature representation, consisting of off-the-shelf concept detectors, to capture the variance in semantic appearance of events. Since it is unknown what similarity metric and query fusion to use in such an event retrieval setting, we perform three experiments on unconstrained web videos from the TRECVID event detection task. It reveals that: retrieval with semantic signatures using normalized correlation as similarity metric outperforms a low-level bag-of-words alternative, multiple queries are best combined using late fusion with an average operator, and event retrieval is preferred over event classification when less than eight positive video examples are available.

This paper proposes a new semantic video representation for few and zero example event detection and unsupervised video event summarization. Different from existing works, which obtain a semantic representation by training concepts over images or entire video clips, we propose an algorithm that learns a set of relevant frames as the concept prototypes from web video examples, without the need for frame-level annotations, and use them for representing an event video. We formulate the problem of learning the concept prototypes as seeking the frames closest to the densest region in the feature space of video frames from both positive and negative training videos of a target concept. We study the behavior of our video event representation based on concept prototypes by performing three experiments on challenging web videos from the TRECVID 2013 multimedia event detection task and the MED-summaries dataset. Our experiments establish that i) Event detection accuracy increases when mapping each video into concept prototype space. ii) Zero-example event detection increases by analyzing each frame of a video individually in concept prototype space, rather than considering the holistic videos. iii) Unsupervised video event summarization using concept prototypes is more accurate than using video-level concept detectors.

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