Topic
Tone mapping
About: Tone mapping is a research topic. Over the lifetime, 1713 publications have been published within this topic receiving 48490 citations.
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Patent•
12 May 2008TL;DR: In this article, a tone mapping technique is used to combine the luminance information of pixels in corresponding locations of the images according to a tone map technique to generate a high dynamic range image.
Abstract: Generating a high dynamic range image includes obtaining a maximum luminance and a minimum luminance of a scene to be captured, setting a first range of exposure values and a second range of exposure values according to the maximum luminance and the minimum luminance, capturing a first image of the scene according to the first range of exposure values and a second image of the scene according to the second range of exposure values, and superposing the images by compositing luminance information of pixels in corresponding locations of the images according to a tone mapping technique.
18 citations
TL;DR: An evaluation of six state‐of‐the‐art HDR video TMOs is presented and it is shown that there are differences between the performance of the T MOs under different ambient lighting levels and theTMOs that perform well on traditional large screen displays also performance well on SSDs at the same given luminance level.
Abstract: Since high dynamic range HDR displays are not yet widely available, there is still a need to perform a dynamic range reduction of HDR content to reproduce it properly on standard dynamic range SDR displays. The most common techniques for performing this reduction are termed tone-mapping operators TMOs. Although mobile devices are becoming widespread, methods for displaying HDR content on these SDR screens are still very much in their infancy. While several studies have been conducted to evaluate TMOs, few have been done with a goal of testing small screen displays SSDs, common on mobile devices. This paper presents an evaluation of six state-of-the-art HDR video TMOs. The experiments considered three different levels of ambient luminance under which 180 participants were asked to rank the TMOs for seven tone-mapped HDR video sequences. A comparison was conducted between tone-mapped HDR video footage shown on an SSD and on a large screen SDR display using an HDR display as reference. The results show that there are differences between the performance of the TMOs under different ambient lighting levels and the TMOs that perform well on traditional large screen displays also perform well on SSDs at the same given luminance level.
18 citations
TL;DR: This work demonstrates the dependency of the perceptual quality of the tone-mapped LDR images on the context: environmental factors, display parameters, and image content itself, and proposes to extend JPEG file format in a backward compatible manner to deal with HDR images also.
Abstract: High-dynamic range (HDR) imaging is expected, together with ultrahigh definition and high-frame rate video, to become a technology that may change photo, TV, and film industries. Many cameras and displays capable of capturing and rendering both HDR images and video are already available in the market. The popularity and full-public adoption of HDR content is, however, hindered by the lack of standards in evalu- ation of quality, file formats, and compression, as well as large legacy base of low-dynamic range (LDR) displays that are unable to render HDR. To facilitate the wide spread of HDR usage, the backward compatibility of HDR with commonly used legacy technologies for storage, rendering, and compression of video and images are necessary. Although many tone-mapping algorithms are developed for generating viewable LDR con- tent from HDR, there is no consensus of which algorithm to use and under which conditions. We, via a series of subjective evaluations, demonstrate the dependency of the perceptual quality of the tone-mapped LDR images on the context: environmental factors, display parameters, and image con- tent itself. Based on the results of subjective tests, it proposes to extend JPEG file format, the most popular image format, in a backward compat- ible manner to deal with HDR images also. An architecture to achieve such backward compatibility with JPEG is proposed. A simple implementation of lossy compression demonstrates the efficiency of the proposed archi- tecture compared with the state-of-the-art HDR image compression. © 2013
18 citations
TL;DR: It is concluded that the optimized methods for backward compatibility to 8-bit LDR displays are superior to the method designed for high profile encoder both for 7-bit and 12-bit mappings in terms of all metrics.
Abstract: High dynamic range (HDR) video compression has until now been approached by using the high profile of existing state-of-the-art H.264/AVC (Advanced Video Coding) codec or by separately encoding low dynamic range (LDR) video and the residue resulted from the estimation of HDR video from LDR video. Although the latter approach has a distinctive advantage of providing backward compatibility to 8-bit LDR displays, the superiority of one approach to the other in terms of the rate distortion trade-off has not been verified yet. In this paper, we first give a detailed overview of the methods in these two approaches. Then, we experimentally compare two approaches with respect to different objective and perceptual metrics, such as HDR mean square error (HDR MSE), perceptually uniform peak signal to noise ratio (PU PSNR) and HDR visible difference predictor (HDR VDP). We first conclude that the optimized methods for backward compatibility to 8-bit LDR displays are superior to the method designed for high profile encoder both for 8-bit and 12-bit mappings in terms of all metrics. Second, using higher bit-depths with a high profile encoder is giving better rate-distortion performances than employing an 8-bit mapping with an 8-bit encoder for the same method, in particular when the dynamic range of the video sequence is high. Third, rather than encoding of the residue signal in backward compatible methods, changing the quantization step size of the LDR layer encoder would be sufficient to achieve a
required quality. In other words, the quality of tone mapping is more important than residue encoding for the performance of HDR image and video coding.
18 citations
Patent•
16 Mar 2016
TL;DR: In this article, the luminance component of the high dynamic range image was obtained and an HDR-to-HDR tone mapper curve was determined. But the tone compression problem was not addressed.
Abstract: Aspects of present principles are directed to methods and apparatus for tone mapping a high dynamic range image. The apparatus includes a processor for performing the following and the method includes the following: obtaining a luminance component of the high dynamic range image; determining an HDR to HDR tone mapper curve; determining a tone compressed image by applying the HDR to HDR tone mapper curve to the luminance component of the high dynamic range image; wherein the HDR to HDR tone mapper curve comprises a first part for dark and mid-tone levels, and a second part for highlights.
17 citations