Takahiro Ogawa

Prof. Takahiro Ogawa

orcid

Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 October 2022 in Computer Methods and Programs in Biomedicine
Verified
Journal Article
Closed access
GLGuang Li
Guang Li
RTRen Togo
Ren Togo
TOTakahiro Ogawa
Takahiro Ogawa
MHMiki Haseyama
Miki Haseyama

18 October 2018 in IEEE Access
Verified
Journal Article
Open access
TOTakahiro Ogawa
Takahiro Ogawa
YSYuma Sasaka
Yuma Sasaka
KMKeisuke Maeda
Keisuke Maeda
MHMiki Haseyama
Miki Haseyama
Video classification based on the user’s preference (information of what a user likes: WUL) is important for realizing human-centered video retrieval. A better understanding of the rationale of WUL would greatly contribute to the support for successful video retrieval. However, few studies have shown the relationship between information of what a user watches (WUW) and WUL. A new method that classifies videos on the basis of WUL using video features and electroencephalogram (EEG) signals collaboratively with a multimodal bidirectional Long Short-Term Memory (Bi-LSTM) network is presented in this paper. To the best of our knowledge, there has been no study on WUL-based video classification using video features and EEG signals collaboratively with LSTM. Firstly, we newly apply transfer learning to WUL-based video classification since the number of labels (liked or not liked) attached to videos by users is small, and it is difficult to classify videos based on WUL. Next, we conduct a user study for showing that the representation of psychophysiological signals calculated from Bi-LSTM is effective for WUL-based video classification. Experimental results showed that our deep neural network feature representations can distinguish WUL for each subject.

6 June 2019 in Computer-Aided Civil and Infrastructure Engineering
Verified
Journal Article
Open access
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KMKeisuke Maeda
Keisuke Maeda
STSho Takahashi
Sho Takahashi
TOTakahiro Ogawa
Takahiro Ogawa
MHMiki Haseyama
Miki Haseyama
This paper presents a convolutional sparse coding (CSC)‐based deep random vector functional link network (CSDRN) for distress classification of road structures. The main contribution of this paper is the introduction of CSC into a feature extraction scheme in the distress classification. CSC can extract visual features representing characteristics of target images because it can successfully estimate optimal convolutional dictionary filters and sparse features as visual features by training from a small number of distress images. The optimal dictionaries trained from distress images have basic components of visual characteristics such as edge and line information of distress images. Furthermore, sparse feature maps estimated on the basis of the dictionaries represent both strength of the basic components and location information of regions having their components, and these maps can represent distress images. That is, sparse feature maps can extract key components from distress images that have diverse visual characteristics. Therefore, CSC‐based feature extraction is effective for training from a limited number of distress images that have diverse visual characteristics. The construction of a novel neural network, CSDRN, by the use of a combination of CSC‐based feature extraction and the DRN classifier, which can also be trained from a small dataset, is shown in this paper. Accurate distress classification is realized via the CSDRN.

17 March 2022 in Sensors
Verified
Journal Article
Open access
PDF file
AWAn Wang
An Wang
RTRen Togo
Ren Togo
TOTakahiro Ogawa
Takahiro Ogawa
MHMiki Haseyama
Miki Haseyama
In this paper, we present a novel defect detection model based on an improved U-Net architecture. As a semantic segmentation task, the defect detection task has the problems of background–foreground imbalance, multi-scale targets, and feature similarity between the background and defects in the real-world data. Conventionally, general convolutional neural network (CNN)-based networks mainly focus on natural image tasks, which are insensitive to the problems in our task. The proposed method has a network design for multi-scale segmentation based on the U-Net architecture including an atrous spatial pyramid pooling (ASPP) module and an inception module, and can detect various types of defects compared to conventional simple CNN-based methods. Through the experiments using a real-world subway tunnel image dataset, the proposed method showed a better performance than that of general semantic segmentation including state-of-the-art methods. Additionally, we showed that our method can achieve excellent detection balance among multi-scale defects.

20 December 2022 in International Journal of Computer Assisted Radiology and Surgery
Verified
Journal Article
Open access
PDF file
GLGuang Li
Guang Li
RTRen Togo
Ren Togo
TOTakahiro Ogawa
Takahiro Ogawa
MHMiki Haseyama
Miki Haseyama
Purpose Considering several patients screened due to COVID-19 pandemic, computer-aided detection has strong potential in assisting clinical workflow efficiency and reducing the incidence of infections among radiologists and healthcare providers. Since many confirmed COVID-19 cases present radiological findings of pneumonia, radiologic examinations can be useful for fast detection. Therefore, chest radiography can be used to fast screen COVID-19 during the patient triage, thereby determining the priority of patient’s care to help saturated medical facilities in a pandemic situation. Methods In this paper, we propose a new learning scheme called self-supervised transfer learning for detecting COVID-19 from chest X-ray (CXR) images. We compared six self-supervised learning (SSL) methods (Cross, BYOL, SimSiam, SimCLR, PIRL-jigsaw, and PIRL-rotation) with the proposed method. Additionally, we compared six pretrained DCNNs (ResNet18, ResNet50, ResNet101, CheXNet, DenseNet201, and InceptionV3) with the proposed method. We provide quantitative evaluation on the largest open COVID-19 CXR dataset and qualitative results for visual inspection. Results Our method achieved a harmonic mean (HM) score of 0.985, AUC of 0.999, and four-class accuracy of 0.953. We also used the visualization technique Grad-CAM++ to generate visual explanations of different classes of CXR images with the proposed method to increase the interpretability. Conclusions Our method shows that the knowledge learned from natural images using transfer learning is beneficial for SSL of the CXR images and boosts the performance of representation learning for COVID-19 detection. Our method promises to reduce the incidence of infections among radiologists and healthcare providers.

5 December 2013 in EURASIP Journal on Advances in Signal Processing
Verified
Journal Article
Open access
PDF file
TOTakahiro Ogawa
Takahiro Ogawa
MHMiki Haseyama
Miki Haseyama