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Application of Underwater Spectral Data for Colour Correction Purposes
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
(English)Article in journal (Refereed) Submitted
URN: urn:nbn:se:uu:diva-93768OAI: oai:DiVA.org:uu-93768DiVA: diva2:167348
Available from: 2005-11-25 Created: 2005-11-25 Last updated: 2010-03-01Bibliographically approved
In thesis
1. Colour Correction of Underwater Images Using Spectral Data
Open this publication in new window or tab >>Colour Correction of Underwater Images Using Spectral Data
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For marine sciences sometimes there is a need to perform underwater photography. Optical properties of light cause severe quality problems for underwater photography. Light of different energies is absorbed at highly different rates under water causing significant bluishness of the images. If the colour dependent attenuation under water can be properly estimated it should be possible to use computerised image processing to colour correct digital images using Beer’s Law.

In this thesis we have developed such estimation and correction methods that have become progressively more complicated and more accurate giving successively better correction results. A process of estimation of downwelling attenuation coefficients from multi or hyper spectral data is a basis for automatic colour restoration of underwater taken images. The results indicate that for each diving site the unique and precise coefficients can be obtained.

All standard digital cameras have built in white balancing and colour enhancement functions designed to make the images as aesthetically pleasing as possible. These functions can in most cameras not be switched off and the algorithms used are proprietary and undocumented. However, these enhancement functions can be estimated. Applying their reverse creates un-enhanced images and we show that our algorithms for underwater colour correction works significantly better when applied to such images.

Finally, we have developed a method that uses point spectra from the spectrometer together with RGB colour images from a camera to generate pseudo-hyper-spectral images. Each of these can then be colour corrected. Finally, the images can be weighted together in the proportions needed to create new correct RGB images. This method is somewhat computationally demanding but gives very encouraging results.

The algorithms and applications presented in this thesis show that automatic colour correction of underwater images can increase the credibility of data taken underwater for marine scientific purposes.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. x+55 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 120
Bildanalys, Colour, Correction, Attenuation, Coefficient, Underwater, Bildanalys
National Category
Computer Vision and Robotics (Autonomous Systems)
urn:nbn:se:uu:diva-6138 (URN)91-554-6403-3 (ISBN)
Public defence
2005-12-16, Polhemsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 09:15
Available from: 2005-11-25 Created: 2005-11-25Bibliographically approved

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