Region-Based Image Retrieval Revisited

Region-based image retrieval (RBIR) technique is revisited. In early attempts at RBIR in the late 90s, researchers found many ways to specify region-based queries and spatial relationships; however, the way to characterize the regions, such as by using color histograms, were very poor at that time. Here, we revisit RBIR by incorporating semantic specification of objects and intuitive specification of spatial relationships. Our contributions are the following. First, to support multiple aspects of semantic object specification (category, instance, and attribute), we propose a multitask CNN feature that allows us to use deep learning technique and to jointly handle multi-aspect object specification. Second, to help users specify spatial relationships among objects in an intuitive way, we propose recommendation techniques of spatial relationships. In particular, by mining the search results, a system can recommend feasible spatial relationships among the objects. The system also can recommend likely spatial relationships by assigned object category names based on language prior. Moreover, object-level inverted indexing supports very fast shortlist generation, and re-ranking based on spatial constraints provides users with instant RBIR experiences.Comment: To appear in ACM Multimedia 2017 (Oral

部位特異的変異導入によるCBFβと相互作用するHIV-1 Vif残基の決定

京都大学0048新制・課程博士博士(医学)甲第18881号医博第3992号新制||医||1009(附属図書館)31832京都大学大学院医学研究科医学専攻(主査)教授 小柳 義夫, 教授 松岡 雅雄, 教授 朝長 啓造学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

General and Practical Tuning Method for Off-the-Shelf Graph-Based Index: SISAP Indexing Challenge Report by Team UTokyo

Despite the efficacy of graph-based algorithms for Approximate Nearest Neighbor (ANN) searches, the optimal tuning of such systems remains unclear. This study introduces a method to tune the performance of off-the-shelf graph-based indexes, focusing on the dimension of vectors, database size, and entry points of graph traversal. We utilize a black-box optimization algorithm to perform integrated tuning to meet the required levels of recall and Queries Per Second (QPS). We applied our approach to Task A of the SISAP 2023 Indexing Challenge and got second place in the 10M and 30M tracks. It improves performance substantially compared to brute force methods. This research offers a universally applicable tuning method for graph-based indexes, extending beyond the specific conditions of the competition to broader uses.Comment: Accepted paper on 2nd place solution of SISAP 2023 Indexing Challenge Task

Adversarial Doodles: Interpretable and Human-drawable Attacks Provide Describable Insights

DNN-based image classification models are susceptible to adversarial attacks. Most previous adversarial attacks do not focus on the interpretability of the generated adversarial examples, and we cannot gain insights into the mechanism of the target classifier from the attacks. Therefore, we propose Adversarial Doodles, which have interpretable shapes. We optimize black b\'ezier curves to fool the target classifier by overlaying them onto the input image. By introducing random perspective transformation and regularizing the doodled area, we obtain compact attacks that cause misclassification even when humans replicate them by hand. Adversarial doodles provide describable and intriguing insights into the relationship between our attacks and the classifier's output. We utilize adversarial doodles and discover the bias inherent in the target classifier, such as "We add two strokes on its head, a triangle onto its body, and two lines inside the triangle on a bird image. Then, the classifier misclassifies the image as a butterfly.

Fast Partitioned Learned Bloom Filter

A Bloom filter is a memory-efficient data structure for approximate membership queries used in numerous fields of computer science. Recently, learned Bloom filters that achieve better memory efficiency using machine learning models have attracted attention. One such filter, the partitioned learned Bloom filter (PLBF), achieves excellent memory efficiency. However, PLBF requires a $O(N^3k)$ time complexity to construct the data structure, where $N$ and $k$ are the hyperparameters of PLBF. One can improve memory efficiency by increasing $N$, but the construction time becomes extremely long. Thus, we propose two methods that can reduce the construction time while maintaining the memory efficiency of PLBF. First, we propose fast PLBF, which can construct the same data structure as PLBF with a smaller time complexity $O(N^2k)$. Second, we propose fast PLBF++, which can construct the data structure with even smaller time complexity $O(Nk\log N + Nk^2)$. Fast PLBF++ does not necessarily construct the same data structure as PLBF. Still, it is almost as memory efficient as PLBF, and it is proved that fast PLBF++ has the same data structure as PLBF when the distribution satisfies a certain constraint. Our experimental results from real-world datasets show that (i) fast PLBF and fast PLBF++ can construct the data structure up to 233 and 761 times faster than PLBF, (ii) fast PLBF can achieve the same memory efficiency as PLBF, and (iii) fast PLBF++ can achieve almost the same memory efficiency as PLBF.Comment: NeurIPS 202

Defense-Prefix for Preventing Typographic Attacks on CLIP

Vision-language pre-training models (VLPs) have exhibited revolutionary improvements in various vision-language tasks. In VLP, some adversarial attacks fool a model into false or absurd classifications. Previous studies addressed these attacks by fine-tuning the model or changing its architecture. However, these methods risk losing the original model's performance and are difficult to apply to downstream tasks. In particular, their applicability to other tasks has not been considered. In this study, we addressed the reduction of the impact of typographic attacks on CLIP without changing the model parameters. To achieve this, we expand the idea of ``prefix learning'' and introduce our simple yet effective method: Defense-Prefix (DP), which inserts the DP token before a class name to make words ``robust'' against typographic attacks. Our method can be easily applied to downstream tasks, such as object detection, because the proposed method is independent of the model parameters. Our method significantly improves the accuracy of classification tasks for typographic attack datasets, while maintaining the zero-shot capabilities of the model. In addition, we leverage our proposed method for object detection, demonstrating its high applicability and effectiveness. The codes and datasets will be publicly available.Comment: Under revie