A simplified method for generation of pseudo natural colours from colour infrared aerial photos

Thomas Knudsen, Brian Pilemann Olsen

Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review


In spite of their high potential for automated discrimination between vegetation and human made objects, colour-infrared (CIR) aerial photos have not been in widespread use for traditional photogrammetric mapping. This is probably due to their awkward colour representation invalidating the visual analytical experience of the stereo analysts doing the actual registration of the topographical data. In this paper, we present a method for generating pseudo natural colour (PNC) representations from CIR photos. This enables the combination of automated vegetation discrimination with traditional manual mapping methods. The method presented is a dramatic simplification of a recently published method, going from a 7 step to a 2 step procedure. The first step is a classification of the input image into 4 domains, based on simple thresholding of a vegetation index and a saturation measure for each pixel. In the second step the blue colour component is estimated using tailored models for each domain. Green and red colour components are taken directly fron the CIR photo. The visual impression of the results from the 2 step method is only slightly inferior to the original 7 step method. The implementation, however, is much simpler, and the logical foundation more straightforward.
Original languageEnglish
Publication date2005
Publication statusPublished - 2005
Event6th Geomatic Week Conference - Barcelona, Spain
Duration: 8 Feb 200511 Feb 2005
Conference number: 6


Conference6th Geomatic Week Conference
Internet address


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