Tone mapping

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

Video display apparatus and video display method

Abstract: A video display apparatus includes: a tone mapping processor that performs a tone mapping process of converting a luminance of a video by using conversion characteristics according to a maximum luminance of the video; and a display that displays the video that has undergone the tone mapping process. The tone mapping processor switches between a first tone mapping process of dynamically changing the conversion characteristics according to a time-depend change in the maximum luminance of the video and a second tone mapping process that is performed using constant conversion characteristics irrespective of the time-depend change in the maximum luminance of the video. When the tone mapping process used is switched from the second tone mapping process to the first tone mapping process, the conversion characteristics used is changed gradually or stepwise from the constant conversion characteristics to dynamically changing conversion characteristics over a plurality of frames.

Regularized tone mapping using edge preserving filters

Abstract: Tone mapping is the process of compressing the dynamic range of a scene to make it compatible with displays with limited dynamic range. In this paper, we present a new approach for tone mapping of high dynamic range (HDR) images using edge-preserving filter. We pose it as a variational problem and derive an optimal solution. We compare the results with some of the existing tone mapping algorithms and show that our algorithm compresses the high dynamic range better while preserving the details and avoiding common artefacts. We use an online dynamic range independent metric for analysing the results by the proposed and existing operators and to detect the deviation from the reference HDR image.

A detail enhancement and dynamic range adjustment algorithm for high dynamic range images

Abstract: Although high dynamic range (HDR) images contain large amounts of information, they have weak texture and low contrast. What's more, these images are difficult to be reproduced on low dynamic range displaying mediums. If much more information is to be acquired when these images are displayed on PCs, some specific transforms, such as compressing the dynamic range, enhancing the portions of little difference in original contrast and highlighting the texture details on the premise of keeping the parts of large contrast, are needed. To this ends, a multi-scale guided filter enhancement algorithm which derives from the single-scale guided filter based on the analysis of non-physical model is proposed in this paper. Firstly, this algorithm decomposes the original HDR images into base image and detail images of different scales, and then it adaptively selects a transform function which acts on the enhanced detail images and original images. By comparing the treatment effects of HDR images and low dynamic range (LDR) images of different scene features, it proves that this algorithm, on the basis of maintaining the hierarchy and texture details of images, not only improves the contrast and enhances the details of images, but also adjusts the dynamic range well. Thus, it is much suitable for human observation or analytical processing of machines.

Contrast-gain-based visual tone mapping for digital photo prints

Abstract: With the popularization of digital photo printing, there is a demand for print image quality that approaches the quality of silver halide photographs. One way to achieve this is through automatic correction of image luminance/tone. The conventional approach based on spatially invariant mapping often causes undesired luminance changes' when enhancing contrast; moreover, luminance changes are also accompanied by changes in contrast. This paper proposes a novel algorithm for the enhancement of the contrast and lightness using spatially variant mapping to achieve high-quality printing of images photographed using digital cameras. First, we define a "contrast-gain" function to quantitatively evaluate the visual contrast that results from tone mapping. Based on this function, the proposed tone mapping algorithm enables independent control of the lightness and contrast through spatially variant processing. Next, we formalize a "shadow-up tone curve," which produces an effect similar to auxiliary lighting during photography. Our contrast-gain-based visual tone mapping method, which uses the shadow-up tone curve in the algorithm, has none of the unnaturalness that arises with a conventional single tone curve. Furthermore, it provides an extremely natural effect similar to that in images photographed by a professional photographer using auxiliary light provided by a reflection board.

Pseudo-color coding method for high-dynamic single-polarization SAR images

Abstract: A raw synthetic aperture radar (SAR) image usually has a 16-bit or higher bit depth, which cannot be directly visualized on 8-bit displays. In this study, we propose a pseudo-color coding method for high-dynamic singlepolarization SAR images. The method considers the characteristics of both SAR images and human perception. In HSI (hue, saturation and intensity) color space, the method carries out high-dynamic range tone mapping and pseudo-color processing simultaneously in order to avoid loss of details and to improve object identifiability. It is a highly efficient global algorithm.