Challa Subrahmanya Sastry


Department of Mathematics, IIT Hyderabad, Pin: 502285.

csastry (AT) math (DOT) iith (DOT) ac (DOT) in
Office: 503, Academic C-Block
Phone (Office): +91 40 2301 6602


·       Education: PhD[IIT Kanpur, Advisor: Prof. P. C. Das], M.Sc(Tech)[JNT University, Hyderabad], B.Sc[Hindu College, Machilipatnam (Nagarjuna University)]

·       Professional Experience: Gained at University of Hyderabad, University of British Columbia, Vancouver, Canada and IIITDM Jabalpur, before joining IIT Hyderabad. 




Wavelets, Sparse Optimization Theory and Inverse Problems




Sparse optimization theory (popularly known as Compressive Sensing) is an interface area between Algebra and Optimization, which aims at providing some classes of linear systems with sparse (or economical) descriptions.  Applications of this research area are far and wide in diverse fields including medical imaging. 


My current research interests lie in Finite frames, Sparsity-seeking optimization techniques and their applications involving Data-driven learning methods and Inverse problems. My previous research, nevertheless, was directed toward Wavelets, Reconstruction  in Tomography.






 Mathematical Methods

 Mathematics Behind Machine Learning

 Wavelets & Applications

 Theory of Frames

 Probability Theory

 Sparse Representation Theory

 Linear Algebra

 Numerical Linear Algebra

 Numerical Analysis

 Image Processing

 Digital Signal Processing

 Compressive Sensing (1 credit)

 Several UG (B.Tech) level core Math Courses.





             Dr. R. Ramunaidu (Currently on faculty at IIPE Visakhapatnam)

             Dr. P. Sasmal  (Currently on faculty at IIT Jodhpur, Co-advised by Dr. Phanindra)

             Dr. Prasad Theeda (Currently on faculty at VIT Vellore, Co-advised by Dr. Phanindra)

             Dr. Munnu Sonkar (Currently PostDoc Fellow at University of Houston, USA)

             Dr. K. Z. Najiya (Currently a PostDoc Fellow at IIT Hyderabad)

             Mr. Shantam Gulati (Pursuing PhD, Co-advised by Dr. Phanindra)

             Mr. Akash Sen (Pursuing PhD)

             Dr. Praveen Kumar (Former Post Doc Fellow,  Currently a senior technical architect in IT industry)

             Dr. M. P. Ranjan (Former Post-Doc Felllow, Currently on faculty at IIT (BHU) Varanasi)

 Guided 8 M.Sc students and Co-guided 2 M.Tech students for their project works



Journal Publications:


  • “Analysis of general weights in weighted l1-2- minimization through applications,” Digital Signal Processing, Vol. 133, 3, 2023 (with K. Z. Najiya)


  • “Interior reconstruction in tomography via prior support constrained compressed sensing,” Journal of Inverse and Ill-posed Problems,  Vol. 31, No. 1, 2023, pp. 77-90 (with M. Sonkar and K. Z. Najiya).


  • “Sparsity-driven deterministic sampling strategy for coded aperture X-ray computed tomography,” Measurement Science and Technology, IoP, Vol. 33, 2022, (with M. Sonkar, P. Sasmal and P. Theeda).


  • “Local recovery bounds for prior support constrained compressed sensing,” Mathematical Notes, Springer, Vol. 111, pp: 93-102, 2022, (with K. Z. Najiya  and M. Sonkar).


  • “Null space property for optimality of minimum frame angle under invertible linear operators,” IEEE Signal Processing Letters, Vol. 28, 1928-1932, 2021 (with P. Sasmal, P. Theeda and P.V. Jampana).


  • “Construction of binary matrices as a union of orthogonal blocks via generalized Euler squares,” IEEE Signal Processing Letters, Vol. 28, 882-886,  2021 (with P. Sasmal, P.V. Jampana).


  • “A novel low-complexity compressed data aggregation method for energy-constrained IoT networks,” IEEE Transactions on Green Communications and Networking, 3, 717-730, 2020. (with M. Amaralingam, P. K. Mishra, P Rajalakshmi, S. S. Channappayya).


  • “Ternary matrices compliant with Restricted Isometry Property: Construction and Application to image retrieval,” J. of Combinatorics, Information & System Sciences, Vol. 44, No. 1-4, pages 285-298, 2019. (with R. Naidu and M. Srinivas)


  • “Construction of highly redundant incoherent unit norm tight frames as a union of orthonormal bases,” Journal of Complexity, Vol. 54, Oct, 2019 (with P. Sasmal and P. Jampana).


  • “Reconstruction of sparse-view tomography via preconditioned Radon sensing matrix,”  J. of Applied Maths & Comp. Vol. 58, 91-104, 2019 (with P. Theeda, P. Kumar and P. Jampana).


  •  “Robust heartbeat detection from multimodal data via CNN-based generalizable information fusion,” IEEE Transactions on Biomedical Engineering, Vol. 66, 710 – 717, 2019. (with S. Chandra and S. Jana).


  • “Novel light weight compressed data aggregation using sparse measurements for IoT networks,” Journal of Networks and Computer Applications, Vol. 121, 119-134, 2018 (with M. Amaralingam, P. K. Mishra, P Rajalakshmi, S. S. Channappayya).


  • “Dictionary-based monitoring of premature ventricular contractions: An ultra-low-cost point-of-care service,”  Artificial Intelligence in Medicine, Vol. 87, 91-104, 2018 (with B.S. Chandra, L. Anumandla and S. Jana).


  • "Composition of binary compressed sensing matrices," IEEE Signal Processing Letters, Vol. 23, 1096-1100, August 2016, (with P. Sasmal, R. R. Naidu, P.V. Jampana)


  • "Deterministic Compressed Sensing matrices: Construction via Euler squares and applications," IEEE Transactions on Signal Processing, Vol. 64, 3566-3575, July 2016, (with R. R. Naidu, P.V. Jampana)


  • "Reliable resource-constrained Telecardiology via Compressive detection of anomalous ECG signals," Computers in Biology and Medicine, Volume 66, 144-153, 2015 (with S. Chandra and S. Jana).


  • "Content based medical image retrieval using dictionary learning," Neurocomputing, Vol. 168, 880-895, 2015 (with M. Srinivas, R. Naidu and C. K. Mohan)


  • "In-plane rotation and scale invariant simultaneous dictionary learning and clustering,"  IEEE Transactions on Image Processing, 22(6), 2013, (with Y. Chen, V. Patel, J.   Philips and R. Chellappa)


  • "Spectral dynamics and regularization of incompletely and irregularly measured data," Differential Equations and Dynamical Systems, Vol.  19(3), pp: 181-197, 2011.


  •  “Network traffic analysis using  singular value decomposition and multiscale transforms,"  Information Sciences, Vol. 177, pp: 5275-5291,  December, 2007 (with S. Rawat, A. K. Pujari and V.P. Gulati)


  • “A modified Gabor function for content based image retrieval," Pattern Recognition Letters, Vol. 28, 2,  pp: 293-300, 2007 (with M. Ravindranath, A.K. Pujari, B.L. Deekshatulu).


  •  “Wavelet based multilevel back projection algorithm for parallel and fan beam scanning geometries,” Int. J. of Wavelets, Multiresolution and Information Processing, Vol. 4, N0. 3, pp: 523-545, 2006 (with P.C. Das)


  • “A Fourier-Radial descriptor algorithm for invariant feature extraction,” Int. J. of Wavelets, Multiresolution and Information processing, Vol. 4, No. 1, pp: 197-212, 2006 (with A. K. Pujari and B. L. Deekshatulu)


  • “A convolution backprojection algorithm for local tomography,” ANZIAM Applied Mathematics, Vol. 46, pp: 341-360, 2005 (with P.C. Das)


  • “A wavelet based multiresolution algorithm for rotation invariant feature extraction,” Pattern Recognition Letters, Vol. 25, Issue 16, pp: 1845-1855, 2004 (with A.K. Pujari, B.L. Deekshatulu, C. Bhagvati)



  • “Region-of-Interest tomography using a composite Fourier-Wavelet algorithm,” Numerical Functional Analysis & Optimization, Vol. 23,  pp: 757-777, 2002 (with P.C. Das)




Conference Proceedings:


  • “Magnetic resonance imaging via weighted l1-p minimization” To appear in the proceedings of 9th  PReMI, ISI Calcutta, 2022, (with K. Z. Najiya).


  • “Kernels for incoherent projection and orthogonal matching pursuit,” To appear in Springer Conf Proceedings, 6th CVIP, IIT Ropar, 2021 (with Himanshu Kandiyal).


  • “Improved performance guarantees for Orthogonal Matching Pursuit and application to dimensionality reduction,” In Machine Vision and Augmented Intelligence—Theory and Applications, Proceedings of 6th MAI, 2021, (with M. Sonkar and L. Tiwari).


  • “Sufficient conditions for the uniqueness of solution of the weighted norm minimization problem,” To appear in LNCS, Proc. of 7th ICMC, 2021 (with K.Z. Najiya and M. Sonkar).


  • “Minimally scaled and incoherent frames,” In Proc. of IEEE-ICSIP, 2018, China (with P. Theeda, P. Sasmal and P. Jampana).


  • “Reconstruction of sparse-view tomography via banded matrices, In LNCS, Vol. 10481, In proc. of ICVGIP, IIT Guwahati, 2016 (with P. Theeda, Praveen Kumar and P. Jampana).


  • "On the existence of equivalence class of RIP compliant matrices, " In Proc. of 11th SampTA, Washington, May 2015, with P. Sasmal and P. Jampana).


  • "Optimization of low-dose tomography via binary sensing matrices, " In Proc. of 17th IWCIA, ISI Calcutta, [Volume 9448, 337-351, Lecture Notes in Computer Science] (with T. Prasad, P. Kumar and P. Jampana).


  • "Reliable Low-Cost Telecardiology: High-Sensitivity Detection of Ventricular Beats using Dictionaries, " In Proc. 16th IEEE Healthcom, Natal, Brazil, 2014.," (with B. Chandra and S. Jana)


  • "Multivariable polynomials for the construction of binary sensing matrices," In Proc. of CMCGS, Singapore, February 2014 (with R. Naidu and P.V.Jampana)


  • "Telecardiology: Hurst exponent based anomaly detection in compressively sampled ECG Signals," In Proc. of 15th  IEEE HealthCom, Lisbon, Portugal, 2013 (with S. Chandra and S. Jana)


  • "Reconstruction from divergent ray projections," In Proc. of SPIE Imaging, San Francisco, USA, 2012, (with S. Singh)


  • "Rotation invariant simultaneous clustering and dictionary learning for image retrieval," In Proc. of IEEE-ICASSP, Kyoto, Japan, 2012 (with Y.Chen, V.Patel, J. Philips, R.Chellappa).


  • "Characterization of ECG signals using multiscale approach," In Proc. of IEEE-SPCOM, 2012, IISc Bangalore, (with K.S. Veena, P.Gupta, M. Amarnath)


  • ‘’Compressed sensing for reconstruction of reflectance spectra from tristimulus values, In IEEE-Vcon Proceedings, 2010, (with M. Ravindranath). 


  •  “Detection of edges in CT images directly projection data,” In Proceedings of Advances in Recent Technologies in Communication and Computing 2009, (with Amit Mishra and Agnivesh Singh).


  • “Application of l1-norm minimization technique to image retrieval,”  Conference Proceedings in I. J. of Electronics and Communication Engg, Vol. 3, No. 8, 1646-1649, 2009 (with S. Jain and A. Mishra).


  • “Regularization of incompletely, irregularly and randomly sampled data,” In 6th  IEEE-ICVGIP Proceedings, Bhubaneswar, December, 2008.


  • “Signal reconstruction from incomplete and misplaced measurements,” In Proc. of 69th EAGE, London, 2007, (with G. Hennenfent, F. J. Herrmann)


  • “Application of wavelets in network security,” in “Enhancing computer security with smart technology,” pp: 209-228, CRC Press,   2005 (with S. Rawat)


  • “Network intrusion detection using wavelet analysis,” Lecture Notes in Computer Science, 3356, pp: 224-232, Springer, 2004 (with S. Rawat).


  • Local image reconstruction from localized projections via multiresolution approach, In Combinatorial and Computational Mathematics, 2004. (with P. C. Das).


  • “Impact of windowing on wavelet based reconstruction in tomograpgy,” Proc. of EMB-Int. Conf. on Biomedical Engineering, IISc, Bangalore, 2001 (with P.C. Das)