True colour retrieval from multiple illuminant scene’s image

This paper presents an algorithm to retrieve the true colour of an image captured under multiple illuminant. The proposed method uses a histogram analysis and K-means++ clustering technique to split the input image into a number of segments. It then determines normalised average absolute difference (NAAD) for each resulting segment’s colour component. If the NAAD of the segment’s component is greater than an empirically determined threshold. It assumes that the segment does not represent a uniform colour area, hence the segment’s colour component is selected to be used for image colour constancy adjustment. The initial colour balancing factor for each chosen segment’s component is calculated using the Minkowski norm based on the principal that the average values of image colour components are achromatic. It finally calculates colour constancy adjustment factors for each image pixel by fusing the initial colour constancy factors of the chosen segments weighted by the normalised Euclidian distances of the pixel from the centroids of the selected segments. Experimental results using benchmark single and multiple illuminant image datasets, show that the proposed method’s images subjectively exhibit highest colour constancy in the presence of multiple illuminant and also when image contains uniform colour areas.