• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.197-200
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• 2014

본 논문은 얼굴의 표정 인식을 이용한 위험상황 인지 알고리즘을 제안한다. 제안방법은 인간의 다양한 감정 표정 중 위험상황을 인지하기 위한 표정인 놀람과 공포의 표정을 인식한다. 제안방법은 먼저 얼굴 영역을 추출하고 검출된 얼굴 영역으로부터 눈 영역과 입술 영역을 추출한다. 각 영역에 Uniform LBP 방법을 적용하여 표정을 판별하고 위험 상황을 인식한다. 제안방법은 Cohn-Kanade 데이터베이스 영상을 대상으로 성능을 평가하였다. 그 결과 표정 인식에 좋은 결과를 보였으며 이를 이용하여 위험상황을 잘 판별하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1390-1403
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• 2016

Facial expression recognition (FER) plays a very significant role in computer vision, pattern recognition, and image processing applications such as human computer interaction as it provides sufficient information about emotions of people. For video-based facial expression recognition, depth cameras can be better candidates over RGB cameras as a person's face cannot be easily recognized from distance-based depth videos hence depth cameras also resolve some privacy issues that can arise using RGB faces. A good FER system is very much reliant on the extraction of robust features as well as recognition engine. In this work, an efficient novel approach is proposed to recognize some facial expressions from time-sequential depth videos. First of all, efficient Local Binary Pattern (LBP) features are obtained from the time-sequential depth faces that are further classified by Generalized Discriminant Analysis (GDA) to make the features more robust and finally, the LBP-GDA features are fed into Hidden Markov Models (HMMs) to train and recognize different facial expressions successfully. The depth information-based proposed facial expression recognition approach is compared to the conventional approaches such as Principal Component Analysis (PCA), Independent Component Analysis (ICA), and Linear Discriminant Analysis (LDA) where the proposed one outperforms others by obtaining better recognition rates.

• Journal of Information Science Theory and Practice
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• 제7권2호
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• pp.32-39
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• 2019

A convolutional neural network (CNN) has been widely used in facial expression recognition (FER) because it can automatically learn discriminative appearance features from an expression image. To make full use of its discriminating capability, this paper suggests a simple but effective method for CNN based FER. Specifically, instead of an original expression image that contains facial appearance only, the expression image with facial geometry visualization is used as input to CNN. In this way, geometric and appearance features could be simultaneously learned, making CNN more discriminative for FER. A simple CNN extension is also presented in this paper, aiming to utilize geometric expression change derived from an expression image sequence. Experimental results on two public datasets (CK+ and MMI) show that CNN using facial geometry visualization clearly outperforms the conventional CNN using facial appearance only.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.1981-1995
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• 2021

When a person tries to conceal emotions, real emotions will manifest themselves in the form of micro-expressions. Research on facial micro-expression recognition is still extremely challenging in the field of pattern recognition. This is because it is difficult to implement the best feature extraction method to cope with micro-expressions with small changes and short duration. Most methods are based on hand-crafted features to extract subtle facial movements. In this study, we introduce a method that incorporates optical flow and deep learning. First, we take out the onset frame and the apex frame from each video sequence. Then, the motion features between these two frames are extracted using the optical flow method. Finally, the features are inputted into an improved MobileNetV2 model, where SVM is applied to classify expressions. In order to evaluate the effectiveness of the method, we conduct experiments on the public spontaneous micro-expression database CASME II. Under the condition of applying the leave-one-subject-out cross-validation method, the recognition accuracy rate reaches 53.01%, and the F-score reaches 0.5231. The results show that the proposed method can significantly improve the micro-expression recognition performance.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제5권2호
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• pp.89-94
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• 2016

본 논문에서는 SIFT 기술자를 이용한 얼굴 특징과 SVM 분류기로 표정인식을 수행하는 방법에 대하여 제안한다. 기존 SIFT 기술자는 물체 인식 분야에 있어 키포인트 검출 후, 검출된 키포인트에 대한 특징 기술자로써 주로 사용되나, 본 논문에서는 SIFT 기술자를 얼굴 표정인식의 특징벡터로써 적용하였다. 표정인식을 위한 특징은 키포인트 검출 과정 없이 얼굴영상을 서브 블록 영상으로 나누고 각 서브 블록 영상에 SIFT 기술자를 적용하여 계산되며, 표정분류는 SVM 알고리즘으로 수행된다. 성능평가는 기존의 LBP 및 LDP와 같은 이진패턴 특징기반의 표정인식 방법과 비교 수행되었으며, 실험에는 공인 CK 데이터베이스와 JAFFE 데이터베이스를 사용하였다. 실험결과, SIFT 기술자를 이용한 제안방법은 기존방법보다 CK 데이터베이스에서 6.06%의 향상된 인식결과를 보였으며, JAFFE 데이터베이스에서는 3.87%의 성능향상을 보였다.

• Journal of Information Processing Systems
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• 제17권4호
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• pp.754-771
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• 2021

In the task of continuous dimension emotion recognition, the parts that highlight the emotional expression are not the same in each mode, and the influences of different modes on the emotional state is also different. Therefore, this paper studies the fusion of the two most important modes in emotional recognition (voice and visual expression), and proposes a two-mode dual-modal emotion recognition method combined with the attention mechanism of the improved AlexNet network. After a simple preprocessing of the audio signal and the video signal, respectively, the first step is to use the prior knowledge to realize the extraction of audio characteristics. Then, facial expression features are extracted by the improved AlexNet network. Finally, the multimodal attention mechanism is used to fuse facial expression features and audio features, and the improved loss function is used to optimize the modal missing problem, so as to improve the robustness of the model and the performance of emotion recognition. The experimental results show that the concordance coefficient of the proposed model in the two dimensions of arousal and valence (concordance correlation coefficient) were 0.729 and 0.718, respectively, which are superior to several comparative algorithms.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
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• pp.126-132
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• 2000

This paper presents a facial expression recognition based on Gabor wavelets that uses a fuzzy C-means(FCM) clustering algorithm and neural network. Features of facial expressions are extracted to two steps. In the first step, Gabor wavelet representation can provide edges extraction of major face components using the average value of the image's 2-D Gabor wavelet coefficient histogram. In the next step, we extract sparse features of facial expressions from the extracted edge information using FCM clustering algorithm. The result of facial expression recognition is compared with dimensional values of internal stated derived from semantic ratings of words related to emotion. The dimensional model can recognize not only six facial expressions related to Ekman's basic emotions, but also expressions of various internal states.

• 융합보안논문지
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• 제14권7호
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• pp.23-28
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• 2014

본 논문에서는 기존에 제안된 LDP(Local Directional Pattern)를 기반으로 얼굴 표정 인식 시스템에 대한 설계 및 구현 방법을 제안한다. LDP는 얼굴 영상을 구성하고 있는 각 화소를 주변 화소들과의 관계를 고려하여 지역적인 미세 패턴(Local Micro Pattern)으로 표현해준다. 새롭게 제시된 LDP에서 생성되는 코드들이 다양한 조건하에서 정확한 정보를 포함할 수 있는지의 여부를 검증할 필요가 있다. 따라서, 새롭게 제안된 지역 미세 패턴인 LDP를 다양한 환경에서 신속하게 검증하기 위한 평가 시스템을 구축한다. 제안된 얼굴 표정인식 평가 시스템에서는 6개의 컴포넌트를 거쳐 얼굴 표정인식률을 계산할 수 있도록 구성하였으며, Gabor, LBP와 비교하여 LDP의 인식률을 검증한다.

• Journal of Information Processing Systems
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• 제9권1호
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• pp.173-188
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• 2013

In Facial Expression Recognition Systems (FERS), only particular regions of the face are utilized for discrimination. The areas of the eyes, eyebrows, nose, and mouth are the most important features in any FERS. Applying facial features descriptors such as the local binary pattern (LBP) on such areas results in an effective and efficient FERS. In this paper, we propose an automatic facial expression recognition system. Unlike other systems, it detects and extracts the informative and discriminant regions of the face (i.e., eyes, nose, and mouth areas) using Haar-feature based cascade classifiers and these region-based features are stored into separate image files as a preprocessing step. Then, LBP is applied to these image files for facial texture representation and a feature-vector per subject is obtained by concatenating the resulting LBP histograms of the decomposed region-based features. The one-vs.-rest SVM, which is a popular multi-classification method, is employed with the Radial Basis Function (RBF) for facial expression classification. Experimental results show that this approach yields good performance for both frontal and near-frontal facial images in terms of accuracy and time complexity. Cohn-Kanade and JAFFE, which are benchmark facial expression datasets, are used to evaluate this approach.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제11권3호
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• pp.284-291
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• 2005

본 연구에서는 학습한 표정 패턴을 기반으로 비디오에서 사람의 얼굴을 검출하고 표정을 분석하여 분류하는 프레임워크를 제안한다. 제안 프레임워크는 얼굴 표정을 인식하는데 있어 공간적 정보 외시간에 따라 변하는 표정의 패턴을 표현하기 위해 표정 특성을 공간적으로 분석한 PCA와 시공간적으로 분석한 Hidden Markov Model(HMM) 기반의 표정 HMM을 이용한다. 표정의 공간적 특징 추출은 시간적 분석 과정과 밀접하게 연관되어 있기 때문에 다양하게 변화하는 표정을 검출하여 추적하고 분류하는데 HMM의 시공간적 접근 방식을 적용하면 효과적이기 때문이다. 제안 인식 프레임워크는 현재의 시각적 관측치와 이전 시각적 결과간의 사후 확률 방법에 의해 완성된다. 결과적으로 제안 프레임워크는 대표적인 6개 표정뿐만 아니라 표정의 정도가 약한 프레임에 대해서도 정확하고 강건한 표정 인식 결과를 보인다. 제안 프레임 워크를 이용하면 표정 인식, HCI, 키프레임 추출과 같은 응용 분야 구현에 효과적이다