I received the Ph.D. degree in electrical engineering from the Indian Institute of Technology, Bombay, in 1998. My thesis examined recovery of depth from defocused images. During the summer of 1998, I was a Visiting Scientist at the Image Communication Laboratory, University of Erlangen, Germany. I was an Assistant Research Scientist at the Center for Automation Research, University of Maryland, College Park, between 1998 and 2000.  I joined the Indian Institute of Technology, Madras in October 2000. I am currently a Professor in the Department of Electrical Engineering and carry out my research work in the Image Processing and Computer Vision (IPCV) Lab. I held visiting positions at the Center for Automation Research, University of Maryland in 2002 and 2005. I have served as committee member in many computer vision conferences. My research interests include depth from defocus, image restoration, shape from focus, super-resolution, face detection and recognition, and higher-order statistical learning. (click here for my publications) I am a co-author of the book Depth from Defocus: A Real Aperture Imaging Approach published by Springer. I received the Humboldt Research Fellowship in 2007 from the Alexander von Humboldt Foundation, Germany. I am an Associate Editor of the IEEE Transactions on Pattern Analysis and Machine Intelligence (PAMI).  

BOOK
1. S. Chaudhuri and A.N. Rajagopalan, Depth from Defocus: A Real Aperture Imaging Approach, Springer-Verlag, New York, 1999.

BOOK CHAPTER
1. A. Kale, N. Cuntoor, B. Yegnanarayana, A.N. Rajagopalan and Rama Chellappa, "Gait-based human identification using appearance matching," in Optical and Digital Techniques for Information Security, Bahram Javidi, Ed. Springer-Verlag, 2004.

JOURNALS

1. A.N. Rajagopalan and S. Chaudhuri, "A variational approach to depth from defocused images," IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 19, no. 10, pp. 1158-1165, 1997.

2. A.N. Rajagopalan and S. Chaudhuri, "Space-variant approaches for the recovery of depth from defocused images," Computer Vision and Image Understanding, vol. 68, no. 3, pp. 309-329, 1997.

3. A.N. Rajagopalan and S. Chaudhuri, "A recursive algorithm for maximum likelihood-based identification of blur from multiple observations," IEEE Transactions on Image Processing, vol. 7, no. 7, pp. 1075-1079, 1998.

4. A.N. Rajagopalan and S. Chaudhuri, "Performance analysis of maximum likelihood estimator for recovery of depth from defocused images and optimal selection of camera parameters," International Journal of Computer Vision, vol. 30, no. 3, pp. 175-190, 1998.

5. A.N. Rajagopalan and S. Chaudhuri, "An MRF model-based approach to simultaneous recovery of depth and restoration from defocused images," IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 21, no. 7, pp. 577-589, 1999.

6. A.N. Rajagopalan and S. Chaudhuri, "MRF model-based identification of shift-variant point spread function for a class of imaging systems," Signal Processing, vol. 76, no. 3, pp. 285-299, 1999.
 
7. A.N. Rajagopalan, Avinash Jain and U.B. Desai, "Data clustering using hierarchical deterministic annealing and higher order statistics," IEEE Transactions on Circuits and Systems-II, vol. 46, no. 8, pp. 1100-1104, 1999.

8. A.N. Rajagopalan, K. Sunil Kumar, Jayashree Karlekar, R. Manivasakan, M. Milind Patil, U. B. Desai, P. G. Poonacha and S. Chaudhuri, "Locating human faces in a cluttered scene," CVGIP : Graphical Models and Image Processing, vol. 62, no. 5, pp. 323-342, 2000.

9. A.N. Rajagopalan, S. Chaudhuri and Rama Chellappa, "A quantitative analysis of error bounds in the recovery of depth from defocused images," Journal of the Optical Society of America A, vol. 17, no. 10, pp. 1722-1731, 2000. 

10. A.N. Rajagopalan and Rama Chellappa, "Higher order statistics-based detection of vehicles in still images," Journal of the Optical Society of America A, vol. 18, no. 12, pp. 3037-3048, 2001.

11. A.N. Rajagopalan and Rama Chellappa, "Higher order statistics-based detection of people/vehicles in images," INSA-A Journal: Special Issue on Image Processing, Vision and Pattern Recognition (invited paper), vol. 67, pp 157-166, 2001.

12. A.N. Rajagopalan, "Clustering using higher order statistics," Electronics Letters, vol. 38, no. 3, pp. 122-124, 2002.

13. A.N. Rajagopalan and V. Phani Kiran, "Motion-free superresolution and the role of relative blur," Journal of the Optical Society of America A, vol. 20, no. 11, pp. 2022-2032, 2003.

14. A.N. Rajagopalan, S. Chaudhuri, and M. Uma, "Depth estimation and image restoration using defocused stereo pairs," IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 26, no. 11, pp. 1521-1525, 2004.

15. Amit Kale, A.N. Rajagopalan, A. Sundaresan, N. Cuntoor, A. RoyChowdhury, V. Kruger, and Rama Chellappa, "Identification of humans using gait," IEEE Transactions on Image Processing, vol. 13, no. 9, pp. 1163-1173, 2004.

16. K.S. Rao and A.N. Rajagopalan, "A probabilistic fusion methodology for face recognition," EURASIP Journal on Applied Signal Processing, vol. 2005, no. 17, pp. 2772-2787, 2005.

17. A.N. Rajagopalan, R. Chellappa and N. Koterba,  "Background learning for robust face recognition with PCA in the presence of clutter," IEEE Transactions on Image Processing, vol. 14, no. 6, pp. 832-843, 2005.

18. S.I. Sadhar and A.N. Rajagopalan, "Image recovery under nonlinear/non-Gaussian degradations," Journal of the Optical Society of America A, vol. 22, no. 4, pp. 604-615, 2005.

19. S.I. Sadhar and A.N. Rajagopalan "Image estimation in film-grain noise," IEEE Signal Processing Letters, vol. 12, no. 3,  pp. 238-241, 2005.

20. J.K. Prasanna and A.N. Rajagopalan, "Image restoration using the particle filter: handling non-causality," IEE Proceedings - Vision, Image and Signal Processing, vol. 153, no. 5,  pp. 650-656, 2006.

21. S.I. Sadhar and A.N. Rajagopalan,  "Restoration of scanned photographic images," Signal Processing, vol. 86, no. 5,  pp.1035-1048, 2006.

22. S.I. Sadhar and A.N. Rajagopalan, "Particle filter for identification of parametric space-variant blur," International Journal of Systemics, Cybernetics and Informatics, vol. 5, pp. 13-19, 2006.

23. K.S. Pradeep and A.N. Rajagopalan, "Improving shape from focus using defocus cue," IEEE Transactions on Image Processing, vol. 16, no. 7.  pp. 1920 - 1925, 2007.

24. A.P. Shanker and A.N. Rajagopalan "Off-line signature verification using DTW," Pattern Recognition Letters, vol. 28, no. 12,  pp. 1407-1414, 2007.

25. A.N. Rajagopalan, K.S. Rao and Y.A. Kumar,. "Face recognition using multiple facial features," Pattern Recognition Letters, vol. 28, no. 3, pp. 335-341, 2007.

26. G.R.K.S. Subrahmanyam, A.N. Rajagopalan and R. Aravind, "Importance sampling Kalman filter for image estimation," IEEE Signal Processing Letters, vol. 14, no. 7,  pp. 453 - 456, 2007.

27. K.V. Suresh, G. Mahesh and A.N. Rajagopalan, "Super-resolution of license plates in real traffic videos," IEEE Transactions on Intelligent Transportation Systems, vol. 8, no. 2, pp. 321-331, 2007.

28. K.V. Suresh and A.N. Rajagopalan, "A robust and computationally efficient super-resolution algorithm," Journal of the Optical Society of America A, vol. 24 no. 4, pp. 984-992, 2007.

29. A. Chakrabarti, A.N. Rajagopalan and R. Chellappa, "Super-resolution of face images using kernel PCA-based prior," IEEE Transactions on Multimedia, vol. 9, no. 4,  pp. 888-892, 2007. 

30. R.R. Sahay and A.N. Rajagopalan, (accepted) "Extension of the shape from focus method for reconstruction of high resolution images",  Journal of the Optical Society of America A, 2007.

31. G.R.K.S. Subrahmanyam, A. N. Rajagopalan and R. Aravind, (conditionally accepted),  "Importance sampling unscented Kalman filter for film-grain noise removal," IEEE Multimedia.

CONFERENCES

1. A.N. Rajagopalan and N.L.M. Murukutla, "Mode S SSR," Proceedings of the Workshop on Satellite Aided Communication, Navigation and Surveillance, Hyderabad, India, February 1992.

2. A.N. Rajagopalan and S. Chaudhuri, "Recovery of depth from defocused images," Proceedings of the National Conference on Communications (NCC'95), IIT Kanpur, pp. 155-159, March 1995.

3. A.N. Rajagopalan and S. Chaudhuri, "A block-shift variant blur model for recovery of depth from defocused images," Proceedings of the IEEE International Conference on Image Processing (ICIP'95), Washington, D.C., pp. 636-639, Oct. 1995.

4. A.N. Rajagopalan and S. Chaudhuri, "A variational approach to depth from defocus," Proceedings of the International Symposium on Intelligent Robotic Systems (ISIRS'95), Bangalore, India, pp. 45-48, Nov. 1995.

5. A.N. Rajagopalan and S. Chaudhuri, "Recovery of depth from defocused images using space-frequency representation," Proceedings of the Indian Conference on Pattern recognition, Image processing and Computer vision (ICPIC'95), IIT Kharagpur,  pp. 95-100, Dec. 1995.

6. A.N. Rajagopalan and S. Chaudhuri, "Recovery of depth from defocused images using AR spectral estimator," Proceedings of the National Conference on Communications (NCC'96), IIT Bombay, pp. 221-224, Feb. 1996.

7. A.N. Rajagopalan and S. Chaudhuri, "Maximum likelihood estimation of blur from multiple observations," Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP'97), Munich, Germany, pp. 2577-2580, April 1997.

8. A.N. Rajagopalan and S. Chaudhuri, "Optimum camera parameter settings for recovery of depth from defocused images," Proceedings of the IEEE International Conference on Computer Vision and Pattern Recognition (CVPR'97), Puerto Rico, pp. 219-224, June 1997.

9. A.N. Rajagopalan, M. Yeasin and S. Chaudhuri, "Data clustering using higher order statistics," Proceedings of the IEEE TENCON '97, Brisbane, Australia, pp. 803-806, Dec. 1997.

10. A.N. Rajagopalan and S. Chaudhuri, "Identification of shift-variant point spread function for a class of imaging systems," Proceedings of the IEEE TENCON `97, Brisbane, Australia, pp. 275-278, Dec. 1997.

11. A.N. Rajagopalan, K. Sunil Kumar, Jayashree Karlekar, R. Manivasakan, M. Milind Patil, U. B. Desai, P. G. Poonacha and S. Chaudhuri, "Finding faces in photographs," Proceedings of the IEEE International Conference on Computer Vision (ICCV'98), Bombay, India, pp. 640-645, Jan. 1998.

12.A.N. Rajagopalan and S. Chaudhuri, "Optimal recovery of depth from defocused images using an MRF model," Proceedings of the IEEE International Conference on Computer Vision (ICCV'98), Bombay, India, pp. 1047-1052, Jan. 1998.
 
13. Avinash Jain, A.N. Rajagopalan and U.B. Desai, "Data clustering using hierarchical deterministic annealing and higher order statistics," Proceedings of the National Conference on Communications (NCC'98), IISc Bangalore, pp. 79-84, Feb. 1998.

14. A.N. Rajagopalan and S. Chaudhuri, "Simultaneous depth recovery and image restoration from defocused images," Proceedings of the IEEE International Conference on Computer Vision and Pattern Recognition (CVPR'99), Fort Collins, Colorado, pp. 348-353, June 1999.

15. A.N. Rajagopalan, Philippe Burlina and Rama Chellappa, "Detection of people in images," Proceedings of the IEEE International Joint Conference on Neural Networks (IJCNN'99), Washington, DC, pp. 2747-2752, July 1999.

16. A.N. Rajagopalan, Philippe Burlina and Rama Chellappa, "Higher order statistical learning for vehicle detection in images," Proceedings of the IEEE International Conference on Computer Vision (ICCV'99), Kerkyra, Greece, pp. 1204-1209, Sept. 1999.

17. A.N. Rajagopalan and Rama Chellappa, "Human motion analysis using higher-order spectra," Proceedings of the Advanced Sensors Federated Laboratory Symposium (ASFL 00), College Park, Maryland, pp. 77-81, March 2000. 
 
18. Rama Chellappa and A.N. Rajagopalan, "Tracking humans in video," Proceedings of the International Conference on Multimedia Processing and Systems (ICMPS'00), Chennai, India, pp. 111-114, August 2000.

19. A.N. Rajagopalan and Rama Chellappa, "Vehicle detection and tracking in video," Proceedings of the IEEE International Conference on Image Processing (ICIP'00), Vancouver, Canada, pp. 351-354, Sept. 2000.

20.  A.N. Rajagopalan and Rama Chellappa, "Higher-order spectral analysis of human motion," Proceedings of the IEEE International Conference on Image Processing (ICIP'00), Vancouver, Canada, pp. 230-233, Sept. 2000.

21. A.N. Rajagopalan, S. Chaudhuri and Rama Chellappa, "Error bounds in depth from defocus," Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing (ICVGIP'00), Bangalore, India, pp.291-298, Dec. 2000.

22. A. Kale, A.N. Rajagopalan and Rama Chellappa, "Recognition of humans using gait," Proceedings of the Federal Labs Symposium, College Park, MD, March 2001.

23. S. Kannumuri and A.N. Rajagopalan, "Human face detection in cluttered color images using skin color and edge information," Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing (ICVGIP'02), Ahmedabad, India, pp. 230-235, Dec. 2002.

24. P.K. Vajapayezula and A.N. Rajagopalan, "Motion-free superresolution," Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing (ICVGIP'02), Ahmedabad, India, pp. 423-428, Dec. 2002.

25. A. Kale, A.N. Rajagopalan, N. Cuntoor and V. Kruger, "Gait-based recognition of humans using continuous HMMs," Proceedings of the IEEE International Conference on Face and Gesture Recognition, Washington, D.C,  pp. 321-326, May 2002.

26. R.K. Singh and A.N. Rajagopalan, "Background learning for robust face recognition," Proceedings of the IEEE International Conference on Pattern Recognition (ICPR'02), Quebec, Canada, pp. 525-528, Aug. 2002.

27. Amit Kale, Naresh Cuntoor, B. Yegnanarayana, A.N Rajagopalan, and Rama Chellappa, "Gait Analysis for Human Identification," Proceedings of the IEEE Intl. Conference on Audio and Video-based biometric person authentication (AVBPA 2003), Surrey, UK, pp. 706-714, 2003.

28. A.N. Rajagopalan, Rama Chellappa and Nathan Kotherba, "Robust face recognition in the presence of clutter," Proceedings of the IEEE Intl. Conference on Audio and Video-based biometric person authentication (AVBPA 2003), Surrey, UK, pp. 1-9, 2003.

29. D.V. Karthik and A.N. Rajagopalan, "Face detection in cluttered background using support vector machines," Proceedings of the National Conference on Communications (NCC'03), IIT, Madras, pp. 468-472, 2003.

30. V. Phani Kiran and A.N. Rajagopalan, "Role of relative blur in motion-free superresolution," Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP'03), Hongkong, 2003

31. S. Ibrahim Sadhar and A.N. Rajagopalan, "Recovery of Nonlinearly Degraded Images," Proceedings of the IEEE International Conference on Image Processing (ICIP -2004), Singapore, October 2004.

32. K. Srinivasa Rao and A.N. Rajagopalan, "A probabilistic fusion technique for face recognition," Proceedings of the European Signal Processing Conference (EUSIPCO'04), Austria, 2004.

33. S. Ibrahim Sadhar and A.N. Rajagopalan, "Restoration of images degraded by sensor non-linearity," Proceedings of the European Signal Processing Conference (EUSIPCO 04), Austria, pp. 497-500, 2004.

34. S. Ibrahim Sadhar and A.N. Rajagopalan, "Particle filter for space-variant blur identification," Proceedings of the International Conference on Systems, Control and Informatics (ICSCI 04), Hyderabad, pp. 299-303, 2004. 

35. K. Srinivasa Rao and A.N. Rajagopalan, "Probabilistic fusion of facial features," Proceedings of the Workshop on Computer Vision, Graphics, and Image Processing (WCVGIP' 04), Gwalior, pp. 45-48, Feb. 2004.

36. S. Ibrahim Sadhar, P.Y. Praveen Kumar and A.N. Rajagopalan, "Particle filters for image restoration," Proceedings of the National Conference on Communications (NCC 04), Bangalore, pp. 111-115, 2004.

37. P.Y. Praveen Kumar, S. Ibrahim Sadhar and A.N. Rajagopalan, "A general recursive framework for image restoration using particle filters," Proceedings of the Asian Conference on Computer Vision (ACCV 2004), Korea, 2004.

38. K. Srinivasa Rao, L.S. Ghadi, Y. Anoop Kumar and  A.N. Rajagopalan, " Robust face recognition by fusion," Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing (ICVGIP'04), Kolkata, India, pp. 669-674, December 2004.

39. K. V. Suresh and A. N. Rajagopalan, "Robust super-resolution imaging," Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2006), Toulouse, France, May 2006.

40. G.R.K.S. Subrahmanyam and A.N. Rajagopalan, "A new extension of Kalman filter to non-Gaussian priors," Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing (ICVGIP'06), Madurai, India, pp. 162-171, December 2006.

41. K.V. Suresh and A.N. Rajagopalan, "Robust space-variant Super-resolution," Proceedings of the IET International Conference on Visual Information Engineering (VIE'06), Bangalore, India, 600-605, pp. 600-605, September 2006.

42. K. V. Suresh and A. N. Rajagopalan, "A discontinuity adaptive method for super-resolution of license plates," Proceedings of the Indian Conference on Vision, Graphics and Image Processing (ICVGIP 2006), Madurai, India, LNCS 4338, pp. 25-34, December 2006.

43. C. Paramanand and A.N. Rajagopalan, "An efficient representation of digital curves with line Segments and elliptical Arcs," Proceedings of the IET International Conference on Visual Information Engineering (VIE'06), Bangalore, India, pp 470-475, September 2006.

44. K.S. Pradeep and A.N. Rajagopalan,  "Improving shape from focus using defocus information," Proceedings of the IEEE International Conference on Pattern Recognition (ICPR 2006), Hongkong, pp 731-734, August 2006.

45. K.V. Suresh and A.N. Rajagopalan, "Super-resolution in the presence of space-variant blur," Proceedings of the IEEE International Conference on Pattern Recognition (ICPR 2006), Hongkong, pp 770-773, August 2006.

46. K.S. Pradeep and  A.N. Rajagopalan,  "A novel method to estimate 3-D shape of microscopic objects," Proceedings of the International Conference on Image Processing, Computer Vision, and Pattern Recognition (IPCV 2006), Las Vegas, Nevada, USA, June 2006.

47. K.V. Suresh and A.N. Rajagopalan, "Robust Super-Resolution: A Bayesian Approach," Proceedings of the Workshop on Computer Vision, Graphics, and Image Processing (WCVGIP'06), Hyderabad, India, pp. 77-82, January 2006.

48. Ayan Chakrabarti and A.N. Rajagopalan, "A kernel PCA-based method for Super-resolution of face images," Proceedings of the Workshop on Computer Vision, Graphics, and Image Processing (WCVGIP'06), Hyderabad, India, January 2006.

49. K.S. Pradeep and A.N. Rajagopalan, "Shape estimation of microscopic objects," Proceedings of the International Conference on Systemics, Cybernetics and Informatics (ICSCI 2006), Hyderabad, India, pp 886-890, January 2006.

50. R.R. Sahay and A.N. Rajagopalan, "Shape from focus: Optimal reconstruction of high-resolution images of 3D objects," Proceedings of the IET International Conference on Visual Information Engineering (VIE 2007), London, UK, July 2007.

51. R.R. Sahay and A.N. Rajagopalan, "High resolution image reconstruction in shape from focus, " Proceedings of the International Conference on Image Processing (ICIP 2007), San Antonio, Texas, USA, pp. 69-72 (II), 2007.

52. G.R.K. S. Subrahmanyam, A. N. Rajagopalan and R. Aravind, "Unscented Kalman filter for image estimation in film-grain noise," Proceedings of the International Conference in Image Processing (ICIP 2007), San Antonio, USA, pp. 17-20 (IV), September 2007.

53. K. V. Suresh and A. N. Rajagopalan, "Super-resolution for real-aperture cameras," Proceedings of the IET International Conference on Visual Information Engineering (VIE 2007), London, UK, July 2007.

54. K. V. Suresh and A. N. Rajagopalan, "Super-resolution using both motion and defocus cues," Proceedings of the IEEE International conference on Image Processing (ICIP 2007), San Antonio, USA, September 2007.

55. K. V. Suresh and A. N. Rajagopalan, "A computationally efficient MAP-MRF framework for super-resolution," Proceedings of the National Conference on VLSI design, Signal Processing and Communications (NC-VSPCom 2007), Tumkur, India, pp. 80-86, February 2007.

56. C. Paramanand and A.N. Rajagopalan, "Representation and transformation of geometric patterns", Proceedings of the International Conference on Systemics, Cybernetics and Informatics, ICSCI-2007, Hyderabad, 2007.