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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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Book ChapterDOI
01 Jan 2015
TL;DR: An automatic contrast enhancement method for WCE videos by using an extension of the recently proposed optimal contrast-tone mapping (OCTM) to color images by utilizing the transformation of each RGB color from of the endoscopy video to the spectral color space La*b* and utilizing the OCTM on the intensity channel alone is obtained.
Abstract: Wireless capsule endoscopy (WCE) is a revolutionary imaging method for visualizing gastrointestinal tract in patients. Each exam of a patient creates large-scale color video data typically in hours and automatic computer aided diagnosis (CAD) are of important in alleviating the strain on expert gastroenterologists. In this work we consider an automatic contrast enhancement method for WCE videos by using an extension of the recently proposed optimal contrast-tone mapping (OCTM) to color images. By utilizing the transformation of each RGB color from of the endoscopy video to the spectral color space La*b* and utilizing the OCTM on the intensity channel alone we obtain our spectral OCTM (SOCTM) approach. Experimental results comparing histogram equalization, anisotropic diffusion and original OCTM show that our enhancement works well without creating saturation artifacts in real WCE imagery.

7 citations

Proceedings ArticleDOI
TL;DR: This work proposes to adapt this quantization step, in the loop of an encoder, to reduce the entropy of the tone mapped video content, and provides an appropriate quantization for each mode of both the Intra and Inter-prediction that is performed in the loops of a block-based encoder.
Abstract: Tone Mapping Operators (TMOs) compress High Dynamic Range (HDR) content to address Low Dynamic Range (LDR) displays. However, before reaching the end-user, this tone mapped content is usually compressed for broadcasting or storage purposes. Any TMO includes a quantization step to convert floating point values to integer ones. In this work, we propose to adapt this quantization, in the loop of an encoder, to reduce the entropy of the tone mapped video content. Our technique provides an appropriate quantization for each mode of both the Intra and Inter-prediction that is performed in the loop of a block-based encoder. The mode that minimizes a rate-distortion criterion uses its associated quantization to provide integer values for the rest of the encoding process. The method has been implemented in HEVC and was tested over two different scenarios: the compression of tone mapped LDR video content (using the HM10.0) and the compression of perceptually encoded HDR content (HM14.0). Results show an average bit-rate reduction under the same PSNR for all the sequences and TMO considered of 20.3% and 27.3% for tone mapped content and 2.4% and 2.7% for HDR content.

7 citations

Book ChapterDOI
Magnus Oskarsson1
15 Jun 2015
TL;DR: This paper presents a novel tone mapping algorithm that is based on \(K\)-means clustering that is able to, not only solve the clustering problem efficiently, but also find the global optimum.
Abstract: The field of high dynamic range imaging addresses the problem of capturing and displaying the large range of luminance levels found in the world, using devices with limited dynamic range. In this paper we present a novel tone mapping algorithm that is based on \(K\)-means clustering. Using dynamic programming we are able to, not only solve the clustering problem efficiently, but also find the global optimum. Our algorithm runs in \(O(N^2K)\) for an image with \(N\) luminance levels and \(K\) output levels. We show that our algorithm gives comparable result to state-of-the-art tone mapping algorithms, but with the additional large benefit of a total lack of parameters. We test our algorithm on a number of standard high dynamic range images, and give qualitative comparisons to a number of state-of-the-art tone mapping algorithms.

7 citations

Proceedings ArticleDOI
01 Sep 2019
TL;DR: A novel tone mapping operator that fusions the multiple versions of a single HDR input obtained by clipping and normalizing its intensity based on a complete set of disjoint intervals is introduced, designed to offer a good rendering of the local structures.
Abstract: This paper introduces a novel tone mapping operator, designed to offer a good rendering of the local structures. The new operator fusions the multiple versions of a single HDR input obtained by clipping and normalizing its intensity based on a complete set of disjoint intervals. Defining the weight map associated to each version to be its clipping interval indicator function promotes contrast enhancement, but induces artifacts when neighboring pixels belong to distinct intervals. We thus propose to smooth out the indicators across neighboring pixels with similar intensity, using a standard cross-bilateral filter. With such weight maps, the fusion operator becomes equivalent to applying histogram equalization on the image regions on which the cross-bilateral filter diffuses the indicators, and is therefore referred to as Bilateral Histogram Equalization (BHE) operator. It compares favorably to previous tone mapping algorithms.

7 citations

Proceedings ArticleDOI
27 Jun 2013
TL;DR: A novel method for compressing High Dynamic Range (HDR) images by Per-Pixel Exposure Mapping (PPEM), which takes advantage of the camera response to enable exposure synthesis which is called Wyckoff set expansion.
Abstract: The needs of a realtime vision aid require that it functions immediately, not merely for production of a picture or video record to be viewed later. Therefore the vision system must offer a high dynamic range (often hundreds of millions to one) that functions in real time. In compliment with the existing efficient and real-time HDR compositing algorithms, we propose a novel method for compressing High Dynamic Range (HDR) images by Per-Pixel Exposure Mapping (PPEM). Unlike any existing methods, PPEM only varies exposure to achieve tone mapping. It takes advantage of the camera response to enable exposure synthesis which we call Wyckoff set expansion. The method evaluates the synthetic exposures in a recursive pairwise process to generate a tone mapped HDR image. The results can be approximated using a look-up table, which can be used for real-time HDR applications.

7 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202330
202274
202167
202089
2019120
2018119