Biography

Dr. Tardi Tjahjadi has extensive expertise in the areas image processing and computer vision. These include: image enhancement; gait recognition; affective computing (i.e., emotion recognition); object tracking and motion estimation; 3D object/scene reconstruction; activity recognition. He has also expertise in expert systems. He has published numerous papers in these areas. He founded and heads the Image Processing and Expert Systems (IPES) Laboratory. He is also the leader of the Information Engineering Research Group of the School.

Dr. Tjahjadi has developed numerous algorithms for: enhancing images; a multiscale step and roof edge detection using cubic B-splines; colour image segmentation; object matching & tracking using constraint cubic B-splines and multiresolution optical ow; recovery of scene structure from an image sequence; multiple-view camera calibration; multiresolution image texture segmentation; octree-based object reconstruction from multiple views; silhouette-based gait and activity recognition, and emotion recognition from facial expression and EEG signals.

Dr. Tjahjadi has also developed expert systems for X-ray rocking curve analysis, X-ray image topography, image contrast enhancement, and differential diagnosis of obstructive sleep apnoea.

Research Interests

Dr. Tjahjadi's current research interests include: affective computing (i.e., emotion recognition from facial expressions, EEG signals and body language); gait recognition for human subject identification; image enhancement; 3D scene reconstruction (from depth from defocus, video sequences and from multiple views); object tracking; autonomous vehicle navigation; and expert systems.

Teaching Interests

ES4E9 Affective Computing

ES3C5 Signal Processing

Selected Publications

Affective Computing:

Fan X & Tjahjadi T, A Dynamic Framework Based on Local Zernike Moment and Motion History Image for Facial Expression Recognition, Pattern Recognition, Vol. 64, pp. 399-406, April 2017.

Piho L & Tjahjadi T, Mutual Information Based Adaptive Windowing of Informative EEG for Emotion Recognition, IEEE Transactions on Affective Computing, Vol. 11, No. 4, October-December 2020, pp. 722-735.

Gait Recognition:

Tang J, Luo J, Tjahjadi T & Guo F, Robust Arbitrary View Gait Recognition based on 3D Partial Similarity Matching, IEEE Transactions on Image Processing, Vol. 26, No. 1, pp. 7-22, January 2017.

Luo J & Tjahjadi T, View and Clothing Invariant Gait Recognition Via 3D Human Semantic Folding, IEEE Access, Vol. 8, No. 1, pp. 100365-100383, June 2020.

Expert Systems:

Partridge T & Tjahjadi T, A Self-Evaluating Expert System for X-Ray Rocking Curve Analysis, International Journal of Intelligent Systems, Vol. 9, 1994, pp. 493-517.

Daniels JE, Chappell MJ, Tjahjadi T & Cayton RM, CADOSA: A Fuzzy Expert System for Differential Diagnosis of Obstructive Sleep Apnoea and Related Conditions, Expert Systems with Applications, Vol. 12, No. 2, 1997, pp. 163-177.

Image Enhancement:

Celik T & Tjahjadi T, Contextual and Variational Contrast Enhancement, IEEE Transactions on Image Processing, Vol. 20, No. 12, December 2011, pp. 3431-3441.

Celik T & Tjahjadi T, Automatic Image Equalization and Contrast Enhancement using Gaussian Mixture Modelling, IEEE Transactions on Image Processing, Vol. 21, No. 1, January 2012, pp. 145-156.

Other Image Processing:

Shin D & Tjahjadi T, Local Hull-Based Surface Construction of Volumetric Data from Silhouettes, IEEE Transactions on Image Processing, Vol. 17, No. 8, August 2008, pp. 1251-1260.

Morshidi M & Tjahjadi T, Gravity Optimised Particle Filter for Hand Tracking, Pattern Recognition, Vol. 47, pp. 194-207, Jan. 2014.

Azhar F & Tjahjadi T, Significant Body Point Labelling and Tracking, IEEE Transactions on Cybernetics, Vol. 44, No. 9, pp. 1673-1685, September 2014.

Li A, Tjahjadi T & Staunton R, Adaptive Deformation Correction of Depth from Defocus for Object Reconstruction, Journal of Optical Society of America, Part A: Optics, Image Science and Vision, Vol. 31, No. 12, pp. 2694-2702, December 2014.

Ibarra-Arenado MJ, Tjahjadi T, Pérez-Oria J, Shadow Detection in Still Road Images using Chrominance Properties of Shadows and Spectral Power Distribution of the Illumination, Sensors, 20(4), Article 1012, 26 pages, February 2020.

Please visit Image Processing and Expert Systems (IPES) Laboratory for the complete list of publications.

Projects and Grants

Selected Projects and Grants:

Safety critical sensor integration for autonomous vehicles (Autotaxi), Feb 2003 - January 2005, funded by Department of Trade and Industry (UK).

Novel Integrated ISTAR: Video enhancement and recognition of human subjects via gait analysis & face verification, Nov 2011 - March 2012, funded by Centre of Defence Enterprise (UK).

ISTAR2 Support to Urban Operations: Action-triggered warning system via action recognition & activity prediction, June 2012 - Nov 2013, funded by Centre of Defence Enterprise (UK).

Development of key technique for gait recognition under significant change in view, July 2013 - June 2014, Collaboration with Central South University (China), funded by Department of Science & Technology, Hunan Province, China.

Imaging system for obstacle detection with sensor fusion, January 2018 - June 2021, funded by Oxford Robotics Limited, UK.

Visual information understanding framework with human perception model and machine learning, January 2020 to January 2023, Collaboration with with City University of Hong Kong, funded by Hong Kong Research Grant Council.