Optimizing tone mapping operators for keypoint detection under illumination changes

Tone mapping operators (TMO) have recently raised interest for their capability to handle illumination changes. However, these TMOs are optimized with respect to perception rather than image analysis tasks like key point detection. Moreover, no work has been done to analyze the factors affecting the optimization of TMOs for such tasks. In this paper, we investigate the influence of two factors-Correlation Coefficient (CC) and Repeatability Rate (RR) of the tone mapped images for the optimization of classical Retinex based models to enhance key point detection under illumination changes. CC-based optimized models aim at increasing the similarity of the tone mapped images. Conversely, RR-based optimized models quantify the optimal detection performance gains. By considering two simple Retinex based models, i.e., Gaussian and bilateral filtering, we show that estimating as precisely as possible the illumination, CC-based optimized models do not necessarily bring to optimal key point detection performance. We conclude that, instead, other criteria specific to RR-based optimized models should be taken into account. Moreover, large gains in performance with respect to existing popular TMOs motivate further research towards optimal tone mapping technique for computer vision applications.