A motion compensated filtering approach to remove sunlight flicker in shallow water images

Nuno Gracias, Shahriar Negahdaripour, Laszlo Neumann, Ricard Prados, Rafael Garcia

Research output: Chapter in Book/Report/Conference proceedingConference contribution

32 Scopus citations

Abstract

A common problem in video surveys in very shallow waters is the presence of strong light fluctuations, due to sun light refraction. Refracted sunlight casts fast moving patterns, which can significantly degrade the quality of the acquired data. Motivated by the growing need to improve the quality of shallow water imagery, we propose a method to remove sunlight patterns in video sequences. The method exploits the fact that video sequences allow several observations of the same area of the sea floor, over time. It is based on computing the image difference between a given reference frame and the temporal median of a registered set of neighboring images. A key observation is that this difference will have two components with separable spectral content. One is related to the illumination field (lower spatial frequencies) and the other to the registration error (higher frequencies). The illumination field, recovered by lowpass filtering, is used to correct the reference image. In addition to removing the sunflickering patterns, an important advantage of the approach is the ability to preserve the sharpness in corrected image, even in the presence of registration inaccuracies. The effectiveness of the method is illustrated in image sets acquired under strong camera motion containing non-rigid benthic structures. The results testify the good performance and generality of the approach.

Original languageEnglish (US)
Title of host publicationOCEANS 2008
DOIs
StatePublished - 2008
EventOCEANS 2008 - Quebec City, QC, Canada
Duration: Sep 15 2008Sep 18 2008

Publication series

NameOCEANS 2008

Other

OtherOCEANS 2008
CountryCanada
CityQuebec City, QC
Period9/15/089/18/08

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Computer Vision and Pattern Recognition
  • Oceanography

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