Karl Skretting

Førsteamanuensis i informasjonsteknologi

Karl Skretting

Kontakt

Telefon: 51832016 / 99489123

E-post: karl.skretting@uis.no

Rom: KE E-438

Organisasjonsenhet

Det teknisk-naturvitenskapelige fakultet

Institutt for data- og elektroteknologi

Kort om meg

Kort biografi: Karl Skretting er fra Njærhein i Hå kommune. Han er gift med Anita og de bor nå i Sandnes. 
Karl startet å studere signalbehandling ved Universitet i Stavanger (UiS) i 1996, navnet var da Høgskolen i Stavanger (HiS). Han fikk  siv.ing. (M.Sc.) grad i 1998 og doktorgrad i 2002. Siden 2002 har han vært førsteamanuensis ved UiS. 

Dette forsker jeg på

My primary research area is signal processing, with a particular focus on dictionary learning. This work culminated in the development and publication of the RLS-DLA algorithm. For more details, including access to the most important algorithms and their evaluations, please visit: https://www.ux.uis.no/~karlsk/dle/index.html. The site provides implementations in MATLAB, and more recently, some Python code as well. 

The first application of dictionary learning I explored—between 1999 and 2011, culminating in an ICASSP paper—was image compression. This work is documented at https://www.ux.uis.no/~karlsk/ICTools/ictools.html. While the method performed well, it is now primarily of educational value, serving as a straightforward example of how image compression can be implemented entirely within the MATLAB environment.

A more relevant and ongoing application of dictionary learning is texture-based image segmentation. My work in this area also began in the previous century and is detailed at https://www.ux.uis.no/~karlsk/tct/index.html. This research culminated in a paper presented at ICIAR 2014, where I introduced the erode algorithm—a greedy alternative to graph-cut methods—which demonstrated excellent performance. Unfortunately, the algorithm has only been available as a somewhat cryptic C implementation compiled as a MEX file for MATLAB. I have recently revisited this work and plan to release a fast, readable, and easy-to-understand Python implementation of the erode algorithm by the end of 2025.

In the early years of my career, I primarily collaborated with colleagues at the University of Stavanger, including J. H. Husøy, K. Engan, and F. Barzideh. More recently, my research partnerships have expanded to include M. Ramezani-Mayiami on graph topology and dictionary learning, G. Alipoor on kernel dictionary learning, and E. H. S. Diop on sparse coding for frequency separation. For further details, please refer to the list of publications below.

Akademisk bakgrunn

Formell undervisningskompetanse:
2007: Kurs i universitetspedagogikk (Uniped) med 100 timer som da dekket kravet til pedagogisk basiskompetanse for universitetslærere ved Uinversitetet i Stavanger

Praktisk undervisning: 
inkludert fag jeg er ansvarlig for (fag jeg har nå med fet skrift):

Fra 2024 Praksis i elektroteknologi (ELE390,  H24-->)
Fra 2021 Styringsteknikk (ELE310,  H21-->)
Vår 2021 Elektroteknikk 1 (ELE100, V21), sammen med M. Khanmohammadi (og laboratoriepersonell og studentassistenter)
Fra 2013 Prosjekt i automatisering og robotteknologi. (ELE630 H13, V14, H14-->)
Fra 2013 Prosjekter i robotteknikk. Fra 2020 ble navnet endret til Praktisk robotteknikk. (ELE610 V13-->, og H17-->), faget ble undervist på norsk om våren fra og med 2013, fra og med 2017 ble faget (gradvis) lagt over til engelsk og undervist både vår- og høstsemester.
Fra 2004-2019 Systemidentifikasjon. (TE6569 V04, MIK130 H05-12, ELE620 H13-19)
2013 Signalbehandling. (ELE500 H13, H16 sammen med J. H. Husøy)
2006-2012 Anvendt signalbehandling. (MIK200 V06-12)
2008-2009 Videregående signalbehandling. (MIK230 H08, H09)
2005-2007 Digital filtrering og koding. (MIK210 H06, avlyst H05 and H07)
2003-2007 Algoritme og kompleksitetsteori. (TE6255 H03, MID170 H04 og V07)
2002-2005 Datagrafikk. (TE0589 H02, H03 og H04, TE0523 V03 og V04, BID110 V05)
1999-2001 Signalbehandling lab. (TE6443 V99, V00 og V01)

Publikasjoner

Vitenskapelige publikasjoner

Alipoor, Ghasem; Skretting, Karl

(2023)

Kernel recursive least squares dictionary learning algorithm.

Digital signal processing (Print).

ISSN 1051-2004.

Volum 141.

DOI: 10.1016/j.dsp.2023.104159

DIop, El Hadji S.; Skretting, Karl; Boudraa, Abdel-Ouahab

(2021)

AM-FM Image Analysis based on Sparse Coding Frequency Separation Approach.

European Signal Processing Conference.

ISSN 2076-1465.

s.610-614.

DOI: 10.23919/Eusipco47968.2020.9287876

Diop, El Hadji S.; Skretting, Karl

(2019)

Frequency Separation Method Based on Sparse Coding.

Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing.

ISSN 1520-6149.

Volum 2019-May.

s.5192-5196.

DOI: 10.1109/ICASSP.2019.8682461

Ramezani-Mayiami, Mahmoud; Skretting, Karl

(2019)

Topology Inference and Signal Representation Using Dictionary Learning.

European Signal Processing Conference.

ISSN 2076-1465.

Volum 2019-September.

DOI: 10.23919/EUSIPCO.2019.8902344

Ramezani-Mayiami, Mahmoud; Hajimirsadeghi, Mohammad; Skretting, Karl; Blum, Rick S.; Poor, H. Vincent

(2019)

Graph Topology Learning and Signal Recovery Via Bayesian Inference. I: 2019 IEEE Data Science Workshop, DSW 2019 Proceedings, June 2-5, 2019, Minneapolis, Minnesota, USA.

IEEE (Institute of Electrical and Electronics Engineers).

ISBN 978-1-7281-0708-0.

s.52-56.

DOI: 10.1109/DSW.2019.8755601

Diop, El Hadji S.; Skretting, Karl; Boudraa, Abdel-Ouahab

(2019)

Multicomponent AM–FM signal analysis based on sparse approximation.

IET Signal Processing.

ISSN 1751-9675.

DOI: 10.1049/iet-spr.2019.0110

Barzideh, Faraz; Urdal, Jarle; Engan, Kjersti; Skretting, Karl; Mdoe, Paschal Francis; Kamala, Benjamin; Brunner, Sara; Hussein, Kidanto

(2018)

Estimation of Missing Data in Fetal Heart Rate Signals Using Shift-Invariant Dictionary.

European Signal Processing Conference.

ISSN 2076-1465.

s.762-766.

DOI: 10.23919/EUSIPCO.2018.8553110

Barzideh, Faraz; Skretting, Karl; Engan, Kjersti

(2017)

Imposing shift-invariance using Flexible Structure Dictionary Learning (FSDL).

Digital signal processing (Print).

ISSN 1051-2004.

Volum 69.

s.162-173.

DOI: 10.1016/j.dsp.2017.06.023

Colomer, Adrian; Naranjo, Valery; Engan, Kjersti; Skretting, Karl

(2017)

Assessment of sparse-based inpainting for retinal vessel removal.

Signal processing. Image communication.

ISSN 0923-5965.

Volum 59.

s.73-82.

DOI: 10.1016/j.image.2017.03.018

Barzideh, Faraz; Skretting, Karl; Engan, Kjersti

(2015)

The flexible signature dictionary.

European Signal Processing Conference.

ISSN 2076-1465.

s.948-952.

DOI: 10.1109/eusipco.2015.7362522

Colomer, Adrian; Naranjo, Valery; Engan, Kjersti; Skretting, Karl

(2015)

Retinal vessel inpainting using recursive least square dictionary learning algorithm. I: 2015 International Conference on Image Processing Theory, Tools and Applications (IPTA), Orléans, France, November 2015.

IEEE (Institute of Electrical and Electronics Engineers).

ISBN 978-1-4799-8635-4.

s.429-433.

DOI: 10.1109/IPTA.2015.7367181

Skretting, Karl; Engan, Kjersti

(2014)

Energy Minimization by alpha-erosion for Supervised Texture Segmentation.

Lecture Notes in Computer Science (LNCS).

ISSN 0302-9743.

s.207-214.

DOI: 10.1007/978-3-319-11758-4_23

Kotu, Lasya Priya; Engan, Kjersti; Skretting, Karl; Måløy, Frode; Ørn, Stein; Woie, Leik; Eftestøl, Trygve

(2013)

Probability mapping of scarred myocardium using texture and intensity features in CMR images.

Biomedical engineering online.

ISSN 1475-925X.

Volum 12.

Hefte 91.

DOI: 10.1186/1475-925X-12-91

Kotu, Lasya Priya; Engan, Kjersti; Skretting, Karl; Ørn, Stein; Woie, Leik; Eftestøl, Trygve

(2013)

Segmentation of Scarred Myocardium in Cardiac Magnetic Resonance Images.

ISRN Biomedical Imaging.

ISSN 2314-5412.

DOI: 10.1155/2013/504594

Skretting, Karl; Engan, Kjersti

(2011)

Image compression using learned dictionaries by RLS-DLA and compared with K-SVD.

Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing.

ISSN 1520-6149.

s.1517-1520.

DOI: 10.1109/ICASSP.2011.5946782

Skretting, Karl; Engan, Kjersti

(2011)

Learned dictionaries for sparse image representation: Properties and results.

Proceedings of SPIE, the International Society for Optical Engineering.

ISSN 0277-786X.

Volum 8138.

DOI: 10.1117/12.892684

Skretting, Karl; Engan, Kjersti

(2010)

Recursive Least Squares Dictionary Learning Algorithm.

IEEE Transactions on Signal Processing.

ISSN 1053-587X.

Volum 58.

Hefte 4.

s.2121-2130.

DOI: 10.1109/TSP.2010.2040671

Engan, Kjersti; Skretting, Karl; Husøy, John Håkon

(2007)

Family of iterative LS-based dictionary learning algorithms, ILS-DLA, for sparse signal representation.

Digital signal processing (Print).

ISSN 1051-2004.

Volum 17.

Hefte 1.

s.32-49.

Engan, Kjersti; Skretting, Karl; Herredsvela, Jostein; Gulsrud, Thor Ole

(2007)

Frame Texture Classification Method (FTCM) Applied on Mammograms for Detection of Abnormalities.

International Journal of Signal Processing.

ISSN 1304-4478.

Volum 4.

Hefte 2.

Skretting, Karl; Husøy, John Håkon

(2006)

Texture classification using sparse frame based representations.

EURASIP Journal on Applied Signal Processing.

ISSN 1110-8657.

Volum 2006.

Hefte 1.

Skretting, Karl; Husøy, John Håkon; Aase, Sven Ole

(2006)

General design algorithm for sparse frame expansions.

Signal Processing.

ISSN 0165-1684.

Volum 86.

Hefte 1.

s.117-126.

Engan, Kjersti; Skretting, Karl; Husøy, John Håkon

(2005)

Denoising of Images Using Signal Dependent Frames and Matching Pursuit. I: Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing.

IEEE Press.

Engan, Kjersti; Skretting, Karl; Husøy, John Håkon

(2005)

ECG Compression Using Signal Dependent Frames and Matching Pursuit. I: Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing.

IEEE Press.

Skretting, Karl; Husøy, John Håkon

(2005)

Frame based texture classification by considering various spatial neighborhoods. I: Proceedings of Norsig.

Tapir Akademisk Forlag.

Herredsvela, Jostein; Engan, Kjersti; Gulsrud, Thor Ole; Skretting, Karl

(2005)

Detection of masses in mammograms by watershed segmentation and sparse representation using learned dictionaries. I: Proceedings NORSIG 2005.

Tapir Akademisk Forlag.

s.35-40.

Herredsvela, Jostein; Engan, Kjersti; Gulsrud, Thor Ole; Skretting, Karl

(2005)

Detection of lesions in mammograms using learned dictionaries and sparse representations.

International Federation for Medical and Biological Engineering Proceedings.

ISSN 1680-0737.

Volum 11.

Aase, Sven Ole; Husøy, John Håkon; Skretting, Karl; Engan, Kjersti

(2001)

General signal expansions for sparse representation.

IEEE Transactions on Signal Processing.

ISSN 1053-587X.

Volum 49.

Hefte 5.

s.1087-1098.

Bøker og kapitler

Skretting, Karl

(2002)

Sparse signal representation using overlapping frames.

ISBN 8247154919.

Formidling

Barzideh, Faraz; Urdal, Jarle; Engan, Kjersti; Skretting, Karl; Mdoe, Paschal Francis; Kamala, Benjamin; Brunner, Sara; Kidanto, Hussein

(2018)

Estimation of Missing Data in Fetal Heart Rate Signals Using Shift-Invariant Dictionary.

26th European Signal Processing Conference (EUSIPCO);

2018-09-03 - .

Urdal, Jarle; Barzideh, Faraz; Engan, Kjersti; Skretting, Karl; Mdoe, Paschal Francis; Kamala, Benjamin; Brunner, Sara; Kidanto, Hussein

(2018)

Missing Data Reconstruction in Fetal Heart Rate Signals using Shift-invariant dictionary.

NOBIM 2018 - National conference on image processing and pattern recognition;

2018-03-12 - 2018-03-13.

Skretting, Karl; Engan, Kjersti

(2017)

Sparse Approximation by Matching Pursuit Using Shift-Invariant Dictionary.

Scandinavian Conference on Image Analysis;

2017-06-12 - 2017-06-14.

Barzideh, Faraz; Skretting, Karl; Engan, Kjersti

(2015)

The flexible signature dictionary.

Eusipco ;

2015-08-31 - 2015-09-04.

Colomer, Adrian; Naranjo, Valery; Engan, Kjersti; Skretting, Karl

(2015)

Retinal vessel inpainting using Recursive Least Square Dictionary Learning Algorithm.

International Conference on Image Processing Theory, Tools and Applications (IPTA), 2015 ;

2015-11-10 - 2015-11-13.

Skretting, Karl; Engan, Kjersti

(2014)

Energy Minimization by alpha-erosion for Supervised Texture Segmentation.

International Conference on Image Analysis and Recognition (ICIAR) ;

2014-10-22 - 2014-10-24.

Skretting, Karl; Engan, Kjersti

(2011)

Image Compression Using Learned Dictionaries by RLS-DLA and Compared with K-SVD.

ICASSP 2011 (International Conference on Acoustics, Speech and Signal Processing);

2011-05-22 - 2011-05-27.

Skretting, Karl; Engan, Kjersti

(2011)

Learned dictionaries for sparse image representation: Properties and results.

SPIE 2011 - Wavelets and Sparsity XIV;

2011-08-21 - 2011-08-24.

Tengesdal, Morten; Rettedal, Arne; Skretting, Karl; Landsvik, Svein

(2006)

Studietilbod og FoU-aktivitetar ved Institutt for data- og elektroteknikk (Ide) ved Universitetet i Stavanger.

Forskningsdagane 2006;

2006-09-28 - 2006-09-30.

Engan, Kjersti; Skretting, Karl; Husøy, John Håkon

(2005)

Denoising of Images Using Signal Dependent Frames and Matching Pursuit.

2005 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2005);

2005-03-18 - 2005-03-23.

Herredsvela, Jostein; Engan, Kjersti; Gulsrud, Thor Ole; Skretting, Karl

(2005)

Detection of masses in mammograms by watershed segmentation and sparse representations using learned dictionaries.

Norsig-2005 Norsk symposium i signalbehandling;

2005-09-22 - 2005-09-24.

Herredsvela, Jostein; Engan, Kjersti; Gulsrud, Thor Ole; Skretting, Karl

(2005)

Detection of lesions in mammograms using learned dictionaries and sparse representations.

3rd European Medical & Biological Engineering Conference IFMBE European Conference on Biomedical Engineering;

2005-11-20 - 2005-11-25.

Herredsvela, Jostein; Engan, Kjersti; Gulsrud, Thor Ole; Skretting, Karl

(2005)

Texture Classification Using Sparse Representations by Learned Compound Dictionaries.

Spars'05 Signal Processing with Adaptive Sparse Structured Representations;

2005-11-16 - 2005-11-18.

Skretting, Karl; Husøy, John Håkon

(2005)

Frame based texture classification by considering various spatial neighborhoods.

NORSIG 2005;

2005-09-22 - 2005-09-24.

Skretting, Karl; Engan, Kjersti; Husøy, John Håkon

(2005)

ECG compression using signal dependent frames and Matching Pursuit.

2005 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2005);

2005-03-18 - 2005-03-23.

Husøy, John Håkon; Skretting, Karl

(2003)

A data oriented design theory for general signal expansions.

Applied Electronics 2003;

2003-09-10 - 2003-09-11.

Engan, Kjersti; Skretting, Karl

(2002)

A Novel Image Denoising Technique Using Overlapping Frames.

2nd. IASTED international conference on Visualization, Imaging, and Image Processing;

2002-09-09 - 2002-09-12.

Husøy, John Håkon; Skretting, Karl

(2002)

Texture classification using sparse frame based representations.

5th NORDIC SIGNAL PROCESSING SYMPOSIUM;

2002-10-04 - 2002-10-07.

Skretting, Karl; Husøy, John Håkon

(2002)

Partial search vector selection for sparse signal representation.

Norwegian Signal Processing Symposium 2003;

2002-10-02 - 2002-10-04.

Aase, Sven Ole; Skretting, Karl; Husøy, John Håkon; Engan, Kjersti

(2001)

Design of Signal Expansions for Sparse Representation.

ICASSP 2000;

Skretting, Karl; Husøy, John Håkon; Aase, Sven Ole

(2001)

A simple design of sparse signal representations using overlapping frames.

2nd International Symposium on Image and Signal Processing;

2001-06-19 - 2001-06-23.

Skretting, Karl; Engan, Kjersti; Husøy, John Håkon; Aase, Sven Ole

(2001)

Sparse representation of images using overlapping frames.

12th Scandinavian Conference on Image Analysis;

2001-06-11 - 2001-06-14.

Husøy, John Håkon; Aase, Sven Ole; Skretting, Karl; Engan, Kjersti

(2000)

Design of general block oriented expansions for efficient signal representation.

utenTitteltekst;

Skretting, Karl; Husøy, John Håkon; Aase, Sven Ole

(1999)

Improved Huffman coding using recursive splitting.

utenTitteltekst;

Kunstnerisk produksjon

Skretting, Karl; Husøy, John Håkon

(2005)

Frame based texture classification by considering various spatial neighborhoods.

Herredsvela, Jostein; Engan, Kjersti; Gulsrud, Thor Ole; Skretting, Karl

(2005)

Detection of masses in mammograms by watershed segmentation and sparse representation using learned dictionaries.