{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T01:38:55Z","timestamp":1783647535216,"version":"3.55.0"},"reference-count":33,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2016,11,16]],"date-time":"2016-11-16T00:00:00Z","timestamp":1479254400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Imaging"],"abstract":"<jats:p>Packaging protects food products from environmental influences, assuring quality and safety throughout shelf life if properly performed. Packaging quality depends on the quality of the packaging material and of the closure or seal. A common problem possibly jeopardizing seal quality is the presence of seal contamination, which can cause a decreased seal strength, an increased packaging failure risk and leak formation. Therefore, early detection and removal of seal contaminated packages from the production chain is crucial. In this work, a pulsed-type active thermography method using the heated seal bars as an excitation source was studied for detecting seal contamination. Thermal image sequences of contaminated seals were recorded shortly after sealing. The detection performances of six thermal image processing methods, based on a single frame, a fit of the cooling profiles, thermal signal reconstruction, pulsed phase thermography, principal component thermography and a matched filter, were compared. High resolution digital images served as a reference to quantify seal contamination, and processed thermal images were mapped to these references. The lowest detection limit (equivalent diameter 0.60 mm) was obtained for the method based on a fit of the cooling profiles. Moreover, the detection performance of this method did not depend strongly on the time after sealing at which recording of the thermal images was started, making it a robust and generally applicable method.<\/jats:p>","DOI":"10.3390\/jimaging2040033","type":"journal-article","created":{"date-parts":[[2016,11,16]],"date-time":"2016-11-16T16:23:04Z","timestamp":1479313384000},"page":"33","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging"],"prefix":"10.3390","volume":"2","author":[{"given":"Karlien","family":"D\u2019huys","sequence":"first","affiliation":[{"name":"KU Leuven Department of Biosystems, MeBioS, Kasteelpark Arenberg 30, B-3001 Heverlee, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5849-4301","authenticated-orcid":false,"given":"Wouter","family":"Saeys","sequence":"additional","affiliation":[{"name":"KU Leuven Department of Biosystems, MeBioS, Kasteelpark Arenberg 30, B-3001 Heverlee, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bart","family":"De Ketelaere","sequence":"additional","affiliation":[{"name":"KU Leuven Department of Biosystems, MeBioS, Kasteelpark Arenberg 30, B-3001 Heverlee, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2016,11,16]]},"reference":[{"key":"ref_1","unstructured":"Robertson, G.L. (2013). Food Packaging: Principles and Practice, CRC Press Taylor & Francis Group."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Dudbridge, M. (2016). Handbook of Seal Integrity in the Food Industry, John Wiley & Sons. [1st ed.].","DOI":"10.1002\/9781118904619"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1080\/08982110701458152","article-title":"Statistical monitoring of a sealing process by means of multivariate accelerometer data","volume":"19","author":"Ostyn","year":"2007","journal-title":"Qual. Eng."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"673","DOI":"10.1111\/j.1365-2621.1998.tb15810.x","article-title":"Ultrasonic imaging of micro-leaks and seal contamination in flexible food packages by the pulse-echo technique","volume":"63","author":"Ozguler","year":"1998","journal-title":"J. Food Sci."},{"key":"ref_5","first-page":"38","article-title":"Performance and integrity of retort pouch seals","volume":"30","author":"Lampi","year":"1976","journal-title":"Food Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"530","DOI":"10.1109\/58.842039","article-title":"High contrast ultrasound images of defects in food package seals","volume":"47","author":"Frazier","year":"2000","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1002\/pts.978","article-title":"Effects of liquid contaminants on heat seal strength of low-density polyethylene film","volume":"25","author":"Mihindukulasuriya","year":"2011","journal-title":"Packag. Technol. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1002\/pts.972","article-title":"Ultrasonic sealing of flexible packaging films\u2014Principles and characteristics of an alternative sealing method","volume":"25","author":"Bach","year":"2012","journal-title":"Packag. Technol. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"275","DOI":"10.1002\/pts.599","article-title":"Non-destructive packaging seal strength analysis and leak detection using ultrasonic imaging","volume":"15","author":"Pascall","year":"2002","journal-title":"Packag. Technol. Sci."},{"key":"ref_10","unstructured":"ASTM F2338 (2013). Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method, Active Standard ASTM."},{"key":"ref_11","unstructured":"ASTM F2391-05 (2011). Standard Test Method for Measuring Package and Seal Integrity Using Helium as the Tracer Gas, Active Standard ASTM."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"338","DOI":"10.1299\/jamdsm.1.338","article-title":"Real-time terahertz diagnostics for detecting microleak defects in the seals of flexible plastic packaging","volume":"1","author":"Morita","year":"2007","journal-title":"J. Adv. Mech. Des. Syst."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Shuangyang, Z. (2010, January 18\u201320). Fast inspection of food packing seals using machine vision. Proceedings of the International Conference on Digital Manufacturing & Automation, Changcha, China.","DOI":"10.1109\/ICDMA.2010.214"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1016\/j.jfoodeng.2012.02.040","article-title":"Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays","volume":"112","author":"Barnes","year":"2012","journal-title":"J. Food Eng."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"423","DOI":"10.1002\/pts.2040","article-title":"Evaluation of a non-destructive high-voltage technique for the detection of pinhole leaks in flexible and semi-rigid packages for foods","volume":"27","author":"Song","year":"2014","journal-title":"Packag. Technol. Sci."},{"key":"ref_16","unstructured":"Maldague, X.P.V. (2001). Theory and Practice of Infrared Technology for Nondestructive Testing, Wiley."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"S91","DOI":"10.1088\/0143-0807\/34\/6\/S91","article-title":"Nondestructive testing with thermography","volume":"34","author":"Tarpani","year":"2013","journal-title":"Eur. J. Phys."},{"key":"ref_18","unstructured":"Ignatowicz, S. (2007). Method and Apparatus for Analyzing Thermo-Graphic images to Detect Defects in Thermally Sealed Packaging. (2007\/0237201 A1), U.S. Patent."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/j.infrared.2004.03.011","article-title":"Infrared image processing and data analysis","volume":"46","author":"Klein","year":"2004","journal-title":"Infrared Phys. Technol."},{"key":"ref_20","unstructured":"Shepard, S.M. (2003). Temporal Noise Reduction, Compression and Analysis of Thermographic Image Data Sequences. (6,516,084), U.S. Patent."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1337","DOI":"10.1117\/1.1566969","article-title":"Reconstruction and enhancement of active thermographic image sequences","volume":"42","author":"Shepard","year":"2003","journal-title":"Opt. Eng."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1002\/asmb.866","article-title":"Statistical methods for automatic crack detection based on vibrothermography sequence-of-images data","volume":"26","author":"Li","year":"2010","journal-title":"Appl. Stoch. Models Bus."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"819","DOI":"10.1007\/s00034-009-9130-7","article-title":"Fast normalized cross-correlation","volume":"28","author":"Yoo","year":"2009","journal-title":"Circ. Syst. Signal Process."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"D\u2019huys, K., Saeys, W., and De Ketelaere, B. (2015, January 20\u201324). Detection of seal contamination in heat sealed food packaging based on active infrared thermography. Proceedings of the Thermosense: Thermal Infrared Applications XXXVII, Baltimore, MD, USA.","DOI":"10.1117\/12.2176559"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1080\/09349840802366617","article-title":"Comparative study of active thermography techniques for the nondestructive evaluation of honeycomb structures","volume":"20","author":"Piau","year":"2009","journal-title":"Res. Nondestruct. Eval."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1016\/S0263-8223(02)00161-7","article-title":"Principal component thermography for flaw contrast enhancement and flaw depth characterization in composite structures","volume":"58","author":"Rajic","year":"2002","journal-title":"Compos. Struct."},{"key":"ref_27","first-page":"120","article-title":"Fast normalized cross-correlation","volume":"10","author":"Lewis","year":"1995","journal-title":"Vis. Interface"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Brunelli, R. (2009). Template Matching Techniques in Computer Vision Theory and Practice, Wiley.","DOI":"10.1002\/9780470744055"},{"key":"ref_29","unstructured":"Briechle, K., and Hanebeck, U.D. (2001, January 16). Template matching using fast normalized cross correlation. Proceedings of the Optical Pattern Recognition XII, Orlando, FL, USA."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1109\/TSMC.1979.4310076","article-title":"A threshold selection method from gray-level histograms","volume":"9","author":"Otsu","year":"1979","journal-title":"IEEE Trans. Syst. Man Cybern."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"741","DOI":"10.1177\/25.7.70454","article-title":"Automatic measurement of sister chromatid exchange frequency","volume":"25","author":"Zack","year":"1977","journal-title":"J. Histochem. Cytochem."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Hochberg, Y., and Tamhane, A.C. (1987). Multiple Comparison Procedures, John Wiley & Sons.","DOI":"10.1002\/9780470316672"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Agresti, A. (2012). Categorical Data Analysis, Wiley.","DOI":"10.1007\/978-3-642-04898-2_161"}],"container-title":["Journal of Imaging"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2313-433X\/2\/4\/33\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:35:39Z","timestamp":1760211339000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2313-433X\/2\/4\/33"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,11,16]]},"references-count":33,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2016,12]]}},"alternative-id":["jimaging2040033"],"URL":"https:\/\/doi.org\/10.3390\/jimaging2040033","relation":{},"ISSN":["2313-433X"],"issn-type":[{"value":"2313-433X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,11,16]]}}}