Automatic generation of natural language description for individual images (a.k.a. image captioning) has attracted extensive research attention. In this paper, we take one step further to investigate the generation of a paragraph to describe a photo stream for the purpose of storytelling. This task is even more challenging than individual image description due to the difficulty in modeling the large visual variance in an ordered photo collection and in preserving the long-term language coherence among multiple sentences. To deal with these challenges, we formulate the task as a sequence-to-sequence learning problem and propose a novel joint learning model by leveraging the semantic coherence in a photo stream. Specifically, to reduce visual variance, we learn a semantic space by jointly embedding each photo with its corresponding contextual sentence, so that the semantically related photos and their correlations are discovered. Then, to preserve language coherence in the paragraph, we learn a novel Bidirectional Attention-based Recurrent Neural Network (BARNN) model, which can attend on the discovered semantic relation to produce a sentence sequence and maintain its consistence with the photo stream. We integrate the two-step learning components into one single optimization formulation and train the network in an end-to-end manner. Experiments on three widely-used datasets (NYC/Disney/SIND) show that the proposed approach outperforms state-of-the-art methods with large margins for both retrieval and paragraph generation tasks. We also show the subjective preference of the machine-generated stories by the proposed approach over the baselines through a user study with 40 human subjects.

We consider learning a sequence classifier without labeled data by using sequential output statistics. The problem is highly valuable since obtaining labels in training data is often costly, while the sequential output statistics (e.g., language models) could be obtained independently of input data and thus with low or no cost. To address the problem, we propose an unsupervised learning cost function and study its properties. We show that, compared to earlier works, it is less inclined to be stuck in trivial solutions and avoids the need for a strong generative model. Although it is harder to optimize in its functional form, a stochastic primal-dual gradient method is developed to effectively solve the problem. Experiment results on real-world datasets demonstrate that the new unsupervised learning method gives drastically lower errors than other baseline methods. Specifically, it reaches test errors about twice of those obtained by fully supervised learning.

Digital storytelling applications are playing an increasingly important role in people's daily life. In contemporary storytelling applications such as PowerPoint presentation and macro/micro blogs, good presentation images are always highly desired by content creators to boost their presentation in an intuitive and attractive way. Existing studies, however, have not yet addressed the challenging problem of how to select the most appropriate presentation images for storytelling. In this paper, we formulate this problem of presentation image suggestion (given a textual query) as selecting images by maximizing visual and semantic diversity from web image search results of suggested queries. The proposed framework consists of two novel components: 1) click-through-based query suggestion, which is designed to suggest textual queries by searching relevant queries in a constructed query graph that can reflect diverse aspects of a given query, and 2) query-based image selection, which selects the most appropriate presentation images by keeping semantic relevance while maximizing visual diversity and quality, using a novel model based on Conditional Random Field (CRF) by individual and correlation characters. We evaluate the proposed approach by comparing with several baselines and a thorough subjective survey. The evaluations show inspiring results using the proposed approach for automatic suggestion of images for storytelling.