Tone expansion using lighting style aesthetics

Bist, Cambodge; Cozot, Rémi; Madec, Gérard; Ducloux, Xavier

doi:10.1016/j.cag.2016.12.006

“…A monotonic function is usually adopted and its shape is adjusted according to the characteristics of the scene present in the image. Typical characteristics are the scene type (dark, average, bright), contrast, amount of saturated pixel, mean and median luminance, and the perceived amount of brightness in the scene [7,[9][10][11]. • Local operators.…”

Section: I R E L a T E D W O R Kmentioning

confidence: 99%

Fully-automatic inverse tone mapping algorithm based on dynamic mid-level tone mapping

Luzardo

¹

,

Aelterman

²

,

Luong

³

et al. 2020

SIP

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High Dynamic Range (HDR) displays can show images with higher color contrast levels and peak luminosities than the common Low Dynamic Range (LDR) displays. However, most existing video content is recorded and/or graded in LDR format. To show LDR content on HDR displays, it needs to be up-scaled using a so-called inverse tone mapping algorithm. Several techniques for inverse tone mapping have been proposed in the last years, going from simple approaches based on global and local operators to more advanced algorithms such as neural networks. Some of the drawbacks of existing techniques for inverse tone mapping are the need for human intervention, the high computation time for more advanced algorithms, limited low peak brightness, and the lack of the preservation of the artistic intentions. In this paper, we propose a fully-automatic inverse tone mapping operator based on mid-level mapping capable of real-time video processing. Our proposed algorithm allows expanding LDR images into HDR images with peak brightness over 1000 nits, preserving the artistic intentions inherent to the HDR domain. We assessed our results using the full-reference objective quality metrics HDR-VDP-2.2 and DRIM, and carrying out a subjective pair-wise comparison experiment. We compared our results with those obtained with the most recent methods found in the literature. Experimental results demonstrate that our proposed method outperforms the current state-of-the-art of simple inverse tone mapping methods and its performance is similar to other more complex and time-consuming advanced techniques.

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“…In this way, the authors propose to use a simple gamma curve as inverse tone mapping operator in which the gamma value is estimated from a multi-linear model that incorporates the key value [6], the number of overexposed pixels, and the geometric mean luminance, as input parameters. Likewise, Bist et al [7] propose a method, based on the conservation of the lighting style aesthetics. As with previous approaches, these authors propose to use a simple gamma correction curve; however, this time the gamma value is computed based on the median of the luminance in the input LDR image.…”

Section: Related Workmentioning

confidence: 99%

“…This parameter is automatically estimated using simple first-order image statistics. Unlike [5] and [7], our proposed expansion function offers better capabilities to increase the perceived image quality of the resulting HDR image than a simple gamma expansion. Furthermore, it is capable to preserve the content creator's artistic intentions inherent to the HDR domain.…”

Section: Related Workmentioning

confidence: 99%

“…The contrast (a) and expansion speed (d) were set manually in 1.25 and 4.0 to increase the contrast and minimize that diffuse whites in the input produce artifacts in the output, respectively. Likewise, the saturation (s) was manually fixed in 1.25 as suggested in [7], and L w,max in 0.67 to specify that we want to reach only 67% of the maximum luminance of the SIM2 display (around 4000 nits). Using the value of m o selected by the participant as the input parameter, HDR inverse tone mapped images were computed in real-time using the proposed function described in Section IV.…”

Section: B Subjective Studymentioning

confidence: 99%

See 1 more Smart Citation

Fully-Automatic Inverse Tone Mapping Preserving the Content Creator’s Artistic Intentions

Luzardo

¹

,

Aelterman

²

,

Luong

³

et al. 2018

2018 Picture Coding Symposium (PCS)

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High Dynamic Range (HDR) displays can show images with higher color contrast levels and peak luminosities than the common Low Dynamic Range (LDR) displays. However, most existing video content is recorded and/or graded in LDR format. To show this LDR content on HDR displays, a dynamic range expansion by using an Inverse Tone Mapped Operator (iTMO) is required. In addition to requiring human intervention for tuning, most of the iTMOs don't consider artistic intentions inherent to the HDR domain. Furthermore, the quality of their results decays with peak brightness above 1000 nits. In this paper, we propose a fully-automatic inverse tone mapping operator based on mid-level mapping. This allows expanding LDR images into HDR with peak brightness over 1000 nits, preserving the artistic intentions inherent to the HDR domain. We assessed our results using full-reference objective quality metrics as HDR-VDP-2.2 and DRIM. Experimental results demonstrate that our proposed method outperforms the current state of the art.

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“…However, dynamic range expansion can be traced back to a simple trick presented by Landis [143], for the purpose of using LDR images in IBL. For display of LDR images on HDR displays, a number of perceptual studies have pointed to the fact that a global mapping may be preferred, either using a gamma function [36,177,178] or a linear scaling [8,226].…”

Section: Single-exposure Techniquesmentioning

confidence: 99%

The high dynamic range imaging pipeline : Tone-mapping, distribution, and single-exposure reconstruction

Eilertsen¹

2018

Linköping Studies in Science and Technology. Dissertations

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Tone expansion using lighting style aesthetics

Cited by 31 publications

References 27 publications

Fully-automatic inverse tone mapping algorithm based on dynamic mid-level tone mapping

Fully-automatic inverse tone mapping algorithm based on dynamic mid-level tone mapping

Fully-Automatic Inverse Tone Mapping Preserving the Content Creator’s Artistic Intentions

The high dynamic range imaging pipeline : Tone-mapping, distribution, and single-exposure reconstruction

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