Faculty Profiles - Noboru Babaguchi

Papers - Noboru Babaguchi

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[Invited Speech] Protection and Utilization of Privacy Information Invited

N. Babaguchi

2013.7

[Keynote Speech] Example-Based Remixing of Multimedia Contents Invited

N. Babaguchi

1st International Workshop on Media Fragment Creation and reMIXing (MMIX'13, Co-located WS at ICME2013) 2013.7

[Invited Speech] Protection and Utilization of Privacy Information Invited

N. Babaguchi

2013.3

Content analysis for home videos Invited Reviewed

Naoko Nitta, Noboru Babaguchi

ITE Transactions on Media Technology and Applications 1 ( 2 ) 91 - 100 2013

Depth-estimation-free condition for projective factorization and its application to 3D reconstruction Reviewed

Yohei Murakami, Takeshi Endo, Yoshimichi Ito, Noboru Babaguchi

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 7727 ( 4 ) 150 - 162 2013

This paper concerns depth-estimation-free conditions for projective factorization. We first show that, using an algebraic approach, the estimation of the projective depth is avoidable if and only if the origins of all camera coordinate systems are lying on a single plane, and optical axes of the coordinate systems point the same direction that is perpendicular to the plane. Next, we generalize the result to the case where the points are possibly restricted on a plane or on a line. The result clearly reveals the trade-off between the freedom of camera motion and that of point location. We also give a least-square-based method for Euclidean reconstruction from the result of the projective reconstruction. The proposed method is evaluated through simulation from the viewpoint of computational time. © 2013 Springer-Verlag.

Efficient DC term encoding scheme based on double prediction algorithms and Pareto probability models Reviewed

Ting-Yu Ko, Chi-Jung Tseng, Hsin-Hui Chen, Jian-Jiun Ding, Noboru Babaguchi

Proceedings - IEEE International Conference on Multimedia and Expo 2013

In this paper, a new algorithm which adopts the techniques of double prediction and the Pareto probability model was applied to encode the DC term in the JPEG compression process. Conventionally, the DC term was encoded by differential coding, i.e., the difference of the DC values between the current block and the previous block. In this paper, we first use the DC terms of four adjacent blocks to predict the current DC value. We then further use the prediction error of the four adjacent blocks to estimate the variance of the prediction error of the current block. We call it the double prediction algorithm. Next, the Pareto distribution is applied to model the probability distribution of the prediction error. Simulation results show that, with the proposed algorithms, the data size required for DC terms is significantly reduced by 25% ∼ 60% and a much higher compression rate can be achieved. © 2013 IEEE.

People counting across spatially disjoint cameras by flow estimation between foreground regions Reviewed

Naoko Nitta, Takayuki Nakazaki, Kazuaki Nakamura, Ryota Akai, Noboru Babaguchi

2013 10th IEEE International Conference on Advanced Video and Signal Based Surveillance, AVSS 2013 414 - 419 2013

Our goal is to develop a method for counting the number of people traveling over a wide area monitored by spatially disjoint multiple cameras with non-overlapping fields of view. The proposed method counts the number of people traversing across each pair of cameras' fields of view by estimating the flows between the foreground regions which have disappeared from and appeared in the camera views within a short time interval. The approach aims at resolving two problems: people in a foreground region can split and merge outside the cameras' fields of view, and the appearance variance of the same person and persons with similar appearance can lead to errors in person re-identification across cameras. The average errors of 0.184 persons in counting the number of people traveling over an area in a university campus monitored by four virtual cameras for 100 minutes have demonstrated the effectiveness of the proposed method. © 2013 IEEE.

Real-time privacy protection system for social videos using intentionally-captured persons detection Reviewed

Tatsuya Koyama, Yuta Nakashima, Noboru Babaguchi

Proceedings - IEEE International Conference on Multimedia and Expo 6 pages 2013

Most social videos, which are uploaded and shared through social networking services (SNSs), e.g., YouTube and Facebook, contain not only intentionally-captured persons (ICPs) but also non-ICPs who are unexpectedly framed in, such as passers-by. Sharing such social videos may infringe on the non-ICPs' privacy but not on the ICPs' in many cases
however, existing systems for video privacy protection simply obscure persons without distinguishing ICPs from non-ICPs. This naive obscuration may spoil the videos. Since this is a critical problem especially for social videos, in this paper, we propose a novel system for automatically generating privacy-protected videos in real-time. Our system localizes ICPs and non-ICPs using ICP detection leveraging the spatial and temporal consistency of ICPs/non-ICPs and obscures the non-ICPs. We have experimentally evaluated the performance of ICP detection and demonstrated the applicability of our system. © 2013 IEEE.

A hybrid mobile-fixed surveillance system, a new solution for public security Case study: abandoned objects' owner alert system"jointly worked"

K.Masui, M.-S.Dao, N.Babaguchi

IEICE Technical Report 2012.3

Intended human object detection for automatically protecting privacy in mobile video surveillance Reviewed

Yuta Nakashima, Noboru Babaguchi, Jianping Fan

MULTIMEDIA SYSTEMS 18 ( 2 ) 157 - 173 2012.3

With the recent popularization of mobile video cameras including camera phones, a new technology, mobile video surveillance, which uses mobile video cameras for video surveillance has been emerging. Such videos, however, may infringe upon the privacy of others by disclosing privacy sensitive information (PSI), i.e., their appearances. To prevent videos from infringing on the right to privacy, new techniques are required that automatically obscure PSI regions. The problem is how to determine the PSI regions to be obscured while maintaining enough video content to present the camera persons' capture-intentions, i.e., what they want to record in their videos to achieve their surveillance tasks. To this end, we introduce a new concept called intended human objects that are defined as human objects essential for capture-intentions, and develop a new method called intended human object detection that automatically detects the intended human objects in videos taken by different camera persons. Through the process of intended human object detection, we develop a system for automatically obscuring PSI regions. We experimentally show the performance of intended human object detection and the contributions of the features used. Our user study shows the potential applicability of our proposed system.

Abandoned Object's Owner Detection: A Case Study of Hybrid Mobile-fixed Video Surveillance System Reviewed

Minh-Son Dao, Riccardo Mattivi, Francesco G. B. De Natale, Keita Masui, Noboru Babaguchi

2012 IEEE NINTH INTERNATIONAL CONFERENCE ON ADVANCED VIDEO AND SIGNAL-BASED SURVEILLANCE (AVSS) 404 - 409 2012

In this paper, a new framework of hybrid mobile-fixed video surveillance system (HMFVSS) is introduced. The purpose of this framework is to overcome common problems of existing mobile or fixed video surveillance systems: (1) moral harassment due to unfriendly or unnaturally installed mobile sensors, and (2) blind areas due to narrow-scope moving of fixed cameras. A case study of abandoned object's owner alert system (AOOAS) is also presented to emphasize the framework's advantages. IP cameras and "Spyglass" (i.e. a mobile camera embedded on glasses) are used as fixed and mobile sensors, respectively. There are three main tasks are inherited, developed, and integrated: (1) image registration for automatically locating abandoned object, (2) common histogram based abandoned object's owner detection, and (3) faces recognition. The experimental results with careful evaluation and comparison with others shows that the proposed framework moves a step ahead in video surveillance system.

Classification based group photo retrieval with Bag of People features Reviewed

Kazuya Shimizu, Yujiro Nakai, Naoko Nitta, Noboru Babaguchi

Proceedings of the 2nd ACM International Conference on Multimedia Retrieval, ICMR 2012 2012

This paper proposes a method for retrieving images containing a specific target person from a given image collection of group photos. This can be realized by query-by-example methods which compare the facial visual features of the target person in the given query image and of each person in the images in the image collection. However, since images are often taken under various conditions, facial appearance of the same person can vary. Since socially related people such as family and friends are often taken photos together, the people co-occurrence relations in the same images can also be a useful clue for image retrieval. Focusing on such people co-occurrence relations, we propose Bag of People (BoP) features which represent both the facial appearances of persons and their co-occurrence relations in the same images. By using the BoP features, a classifier for classifying images into two classes, images containing the target person and other images, can be trained from a small number of images labeled by user's relevance feedback. Furthermore, since the labeled images obtained by relevance feedback are much fewer than unlabeled images in the image collection, an active learning method is used to select useful images to train the classifier. When retrieving images of 24 persons in total from 550 images, after five feedback iterations, the mean average precision of 0.94 was obtained by considering the people co-occurrence relations, as against 0.69 when considering only the target person. Copyright © 2012 ACM.

Extracting Context Information from Microblog based on Analysis of Online Reviews Reviewed

Takumi Takehara, Shohei Miki, Naoko Nitta, Noboru Babaguchi

2012 IEEE INTERNATIONAL CONFERENCE ON MULTIMEDIA AND EXPO WORKSHOPS (ICMEW) 248 - 253 2012

Recommender systems automatically determine suitable items for users. Although preferences or context of users have been widely utilized in order to evaluate the suitability of the items for users, the surrounding context have little been considered. Focusing on that many ordinary human beings voluntarily report their observations of the current situation of the world to microblogs, this paper proposes a recommender system which not only recommends suitable restaurants to users based on their preferences and context but also provides the surrounding context information reported to microblogs which will further affect the users' restaurant selection behaviors. In particular, considering that such influential surrounding context information in microblogs includes keywords related to restaurant assessment, we propose a method for automatically determining the keywords to extract the context information by analyzing online reviews, which have been gathered also from ordinary human beings over a long period of time. The experiments by using Twitter as microblogs and Tabelog, a popular online restaurant review site in Japan, to obtain online reviews, indicated that the influential context information can be extracted from Twitter with the highest recall of 93.3% by using the area-related keywords. Additionally using the restaurant-related keywords was effective in removing irrelevant information obtaining the precision of 15.9%.

DELIVERY METHOD FOR VIEWER-SPECIFIC PRIVACY PROTECTED VIDEO USING DISCRETE WAVELET TRANSFORM Reviewed

Naoya Fukuoka, Yoshimichi Ito, Noboru Babaguchi

2012 IEEE INTERNATIONAL CONFERENCE ON IMAGE PROCESSING (ICIP 2012) 2285 - 2288 2012

This paper presents a delivery method for viewer-specific privacy protected video, where "viewer-specific" implies that the way of privacy protection (e.g., box, mosaic, transparency) varies according to viewer's authority. In this method, in order to reduce the load of a delivery server, viewer-specific privacy protected videos are not produced at the delivery server, but they are produced at each viewer's terminal. The delivery server extracts and decomposes the information of human objects, and then embeds the information into background images using information hiding technique. Each viewer extracts a part of the decomposed information of human objects according to his/her authority, and then produces privacy protected video by integrating the extracted information. In this method, the discrete wavelet transform (DWT) plays a key role. The proposed method is evaluated through experiments.

MARKOV RANDOM FIELD-BASED REAL-TIME DETECTION OF INTENTIONALLY-CAPTURED PERSONS Reviewed

Tatsuya Koyama, Yuta Nakashima, Noboru Babaguchi

2012 IEEE INTERNATIONAL CONFERENCE ON IMAGE PROCESSING (ICIP 2012) 1377 - 1380 2012

Most videos taken by videographers contain intentionally-captured persons (ICPs), who are essential for what the videographers want to express in their video. This paper presents a method to detect ICPs in real-time. Whether a person in a video is an ICP or not is reflected in features such as the person's motion and camera motion, which are thus beneficial for detecting ICPs. However, estimating camera motion is computationally expensive. For real-time detection, we use samples of acceleration and angular velocity obtained from inertial sensors instead of estimating camera motion. Considering that pairwise constraints based on differences between persons' sizes also improve the detection performance, we model the ICPs using Markov random field. We experimentally evaluate the performance of our method and demonstrate that it works in real-time.

Tablet Owner Authentication Based on Behavioral Characteristics of Multi-Touch Actions Reviewed

Kumi Nakamura, Kazuhiro Kono, Yoshimichi Ito, Noboru Babaguchi

2012 21ST INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION (ICPR 2012) 3431 - 3434 2012

This paper proposes a method for tablet owner authentication based on behavioral characteristics of multiple fingers' actions called multi-touch actions. The method is based on dynamic time warping, which has been commonly used for authentication using pentablet or single finger's actions, but another problem arises due to the use of multi-touch actions (e. g., identifying fingers). We also provide methods for these problems. Using proposed method, we evaluate the authentication accuracies for several types of multi-touch actions through experiments.

Indoor Positioning System Using Digital Audio Watermarking Reviewed

Yuta Nakashima, Ryosuke Kaneto, Noboru Babaguchi

IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS E94D ( 11 ) 2201 - 2211 2011.11

Recently, a number of location-based services such as navigation and mobile advertising have been proposed. Such services require real-time user positions. Since a global positioning system (GPS), which is one of the most well-known techniques for real-time positioning, is unsuitable for indoor uses due to unavailability of GPS signals, many indoor positioning systems (IPSs) using WLAN, radio frequency identification tags, and so forth have been proposed. However, most of them suffer from high installation costs. In this paper, we propose a novel IPS for real-time positioning that utilizes a digital audio watermarking technique. The proposed IPS first embeds watermarks into an audio signal to generate watermarked signals, each of which is then emitted from a corresponding speaker installed in a target environment. A user of the proposed [PS receives the watermarked signals with a mobile. device equipped with a microphone, and the watermarks are detected in the received signal. For positioning, we model various effects upon watermarks due to propagation in the air, i.e., delays, attenuation, and diffraction. The model enables the proposed IPS to accurately locate the user based on the watermarks detected in the received signal. The proposed IPS can be easily deployed with a low installation cost because the IPS can work with off-the-shelf speakers that have been already installed in most of the indoor environments such as department stores, amusement arcades, and airports. We experimentally evaluate the accuracy of positioning and show that the proposed IPS locates the user in a 6 m by 7.5 m room with root mean squared error of 2.25 m on average. The results also demonstrate the potential capability of real-time positioning with the proposed IPS.

Example-based video remixing Reviewed

Naoko Nitta, Noboru Babaguchi

MULTIMEDIA TOOLS AND APPLICATIONS 51 ( 2 ) 649 - 673 2011.1

A video remix is generally created by arranging selected video clips and combining them with other media streams such as audio clips and video transition effects. This paper proposes a system for semi-automatically creating video remixes of good expressive quality. Given multiple original video clips, audio clips, and transition effects as the input, the proposed system generates a video remix by five processes: I) video clip sequence generation, II) audio clip selection, III) audio boundary extraction, IV) video segment extraction, and V) transition effect selection, based on the spatial and temporal structural patterns automatically learned from professionally created video remix examples. Experiments using movie trailers of action genre as video remix examples not only demonstrate that video remixing by professionals can be imitated based on examples but also reveal that the video clip sequence generation and audio clip selection are the most important processes to improve the perceived expressive quality of video remixes.

Automatic generation of privacy-protected videos using background estimation Reviewed

Yuta Nakashima, Noboru Babaguchi, Jianping Fan

Proceedings - IEEE International Conference on Multimedia and Expo 2011

Recently, video sharing services such as YouTube and Daily-motion have become popular and many videos taken with mobile video cameras are uploaded to such a video sharing service. However, such videos can infringe on the privacy right of people in the videos because they may contain privacy sensitive information (PSI) of the people, i.e., their appearances. This strongly motivates us to develop a technique to generate privacy-protected videos. In this paper, we propose a novel system for automatic generation of privacy-protected videos based on background estimation. In most conventional techniques, objects that contain PSI are detected and obscured by, e.g., blurring. Conversely, in our system, background pixels are estimated and then substituted with intended human objects that are essential for the camera person's capture intention. We quantitatively evaluate our system to demonstrate its potential applicability. © 2011 IEEE.

Extracting intentionally captured regions using point trajectories Reviewed

Yuta Nakashima, Noboru Babaguchi

MM'11 - Proceedings of the 2011 ACM Multimedia Conference and Co-Located Workshops 1417 - 1420 2011

When camera persons take videos with mobile video cameras, they usually have capture intentions, i.e., what they want to express in their videos, and there are intentionally captured regions (ICRs) in the video frames that are essential for the capture intentions. Extracting ICRs is thus beneficial for wide range of applications such as video summarization and video adaptation for small displays. In this paper, we present a novel method for automatically extracting ICRs. A camera person usually moves his/her camera so that ICRs can be arranged in appropriate positions in video frames
therefore, ICRs can yield specific motion. This observation indicates that such specific motion is a vital cue for extracting ICRs. The proposed method represents motion by point trajectories, which are long-term trajectories of spatially dense points in video frames, and extracts ICRs using an ICR model based on the point trajectories. We experimentally evaluate the proposed method to demonstrate its potential applicability. Copyright 2011 ACM.

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Papers - Noboru Babaguchi