Tone mapping

About: Tone mapping is a research topic. Over the lifetime, 1713 publications have been published within this topic receiving 48490 citations.

Extending dynamic range of two color images under different exposures

Abstract: We present a method of extending the dynamic range of a picture with two different exposure images. Since pictures under different exposure times show different scene dynamic ranges, if we make use of the visible information of each different exposure image, we can recover a high dynamic range image which contains what cannot be visualized by an auto-exposure time. In this method, we did not follow the ordinary fusion methods, which were based on multi-layered or radiance map based approach of multiple images. Instead, we used the filling method of undesirable regions of an auto-exposure picture, preserving its overall image quality. Our filling method uses the gradient information of the visible regions and recovers the saturated regions by the energy minimization approach. The results show that our fusion method is simple and practical to make a HDR image, if we have two proper exposure images.

Feature point detection under extreme lighting conditions

Abstract: This paper evaluates the suitability of High Dynamic Range (HDR) imaging techniques for feature point detection under extreme lighting conditions. The conditions are extreme in respect to the dynamic range of the lighting within the test scenes used. This dynamic range cannot be captured using standard low dynamic range imagery techniques without loss of detail. Four widely used feature point detectors are used in the experiments: Harris corner detector, Shi-Tomasi, FAST and Fast Hessian. Their repeatability rate is studied under changes of camera viewpoint, camera distance and scene lighting with respect to the image formats used. The results of the experiments show that HDR imaging techniques improve the repeatability rate of feature point detectors significantly.

Image brightness controlling apparatus and method thereof

Abstract: Provided are an image brightness control device and an image brightness control method for improving the definition of brightness of the entire image and/or improving the definition of brightness of local areas using local brightness information. The image brightness controlling device includes: a preprocessing unit acquiring an offset table for controlling a dynamic range corresponding to an image range of an input image using brightness values of color data of the input image; and a tone mapping unit mapping the offset table onto the color data. It is possible to improve the definition of brightness so as to correspond to the characteristic of the input image, by automatically considering how to reflect a distribution characteristic of an image.

Which tone-mapping operator is the best? A comparative study of perceptual quality.

Abstract: Tone-mapping operators (TMOs) are designed to generate perceptually similar low-dynamic-range images from high-dynamic-range ones. We studied the performance of 15 TMOs in two psychophysical experiments where observers compared the digitally generated tone-mapped images to their corresponding physical scenes. All experiments were performed in a controlled environment, and the setups were designed to emphasize different image properties: in the first experiment we evaluated the local relationships among intensity levels, and in the second one we evaluated global visual appearance among physical scenes and tone-mapped images, which were presented side by side. We ranked the TMOs according to how well they reproduced the results obtained in the physical scene. Our results show that ranking position clearly depends on the adopted evaluation criteria, which implies that, in general, these tone-mapping algorithms consider either local or global image attributes but rarely both. Regarding the question of which TMO is the best, KimKautz ["Consistent tone reproduction," in Proceedings of Computer Graphics and Imaging (2008)] and Krawczyk ["Lightness perception in tone reproduction for high dynamic range images," in Proceedings of Eurographics (2005), p. 3] obtained the better results across the different experiments. We conclude that more thorough and standardized evaluation criteria are needed to study all the characteristics of TMOs, as there is ample room for improvement in future developments.