Noise, flicker, temporal inconsistencies disturb the tone mapping creation for High Dynamic Range image (HDR). A method to alleviate these artifacts in tone mapped HDR video sequences is presented in this paper. A temporal filtering is developed in order to minimize undesirable artifacts in the low dynamic range image reconstruction process. In the experiments, tone mapping is applied on video sequences obtained by a logarithmic camera. This temporal process provides visual comfort without any kind of blink and prevents Low Dynamic Range (LDR) videos to be disturbed by some random brightness values of isolated pixels.
This paper presents a new shock filter for image restoration and enhancement by incorporating diffusion information coming for an hourglass filter. Shock filter represents an important family in the field of non-linear Partial Differential Equations (PDEs) models for image restoration and enhancement. Commonly, the smoothed second order derivative of the image assists this type of method in the deblurring mechanism via of non-linear PDEs models. The advantage of the proposed approach is to insert information issued of a non-linear tensor, i.e., the hourglass filter, in a shock filter process. Technically, the non-linear spatial averaging is more precise to enhance images and sharpen contours efficiently simultaneously. The method is compared to 5 other PDE techniques, presenting its interest, robustness and reliability, as, for example, without creating a grainy effect around deblurred edges by visualizing isophote lines.
High Dynamic Range (HDR) videos are intended to capture the full range of luminance that can be found in a real world environment. But, as display devices with restricted luminance range are still the most common ones, the need for efficient tone mapping tools remains. Applying a variable base logarithmic compression curve on HDR values is a method that gives good results on static images. Video mapping requires further processing, in order to maintain correct contrast over the different frames and to minimize undesirable artifacts such as flicker and temporal incoherencies when the overall lighting conditions vary. This paper describes a new method for a real time automatic calculation of the logarithmic function base, depending on the characteristics of successive frames in a sequence. Compared to some well-known operators, our proposal better performs in terms of temporal coherency and overall contrast.
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