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Showing papers on "Tone mapping published in 2010"


Book
28 May 2010
TL;DR: The Human Visual System and HDR Tone Mapping and Frequency Domain and Gradient Domain Tone Reproduction and an Image-Based Lighting List of Symbols References Index are presented.
Abstract: Foreword Preface 1 Introduction 2 Light And Color 3 HDR Image Encodings 4 HDR Image Capture 5 Display Devices 6 The Human Visual System and HDR Tone Mapping 7 Spatial Tone Reproduction 8 Frequency Domain and Gradient Domain Tone Reproduction 9 Image-Based Lighting List of Symbols References Index

1,484 citations


Journal ArticleDOI
TL;DR: A new tone mapping operator that performs local linear adjustments on small overlapping windows over the entire input image so that image structures can be preserved even in challenging high dynamic range images that contain either abrupt radiance change, or relatively smooth but salient transitions.
Abstract: This paper introduces a new tone mapping operator that performs local linear adjustments on small overlapping windows over the entire input image. While each window applies a local linear adjustment that preserves the monotonicity of the radiance values, the problem is implicitly cast as one of global optimization that satisfies the local constraints defined on each of the overlapping windows. Local constraints take the form of a guidance map that can be used to effectively suppress local high contrast while preserving details. Using this method, image structures can be preserved even in challenging high dynamic range (HDR) images that contain either abrupt radiance change, or relatively smooth but salient transitions. Another benefit of our formulation is that it can be used to synthesize HDR images from low dynamic range (LDR) images.

150 citations


Journal ArticleDOI
TL;DR: A global histogram adjustment based tone mapping operator is presented, which well reproduces global contrast for high dynamic range images and adaptive contrast adjustment is carried out using this operator in the local regions to reproduce local contrast and ensure better quality.

142 citations


Proceedings ArticleDOI
15 Dec 2010
TL;DR: This work presents a full-reference video quality metric geared specifically towards the requirements of Computer Graphics applications as a faster computational alternative to subjective evaluation.
Abstract: Numerous current Computer Graphics methods produce video sequences as their outcome. The merit of these methods is often judged by assessing the quality of a set of results through lengthy user studies. We present a full-reference video quality metric geared specifically towards the requirements of Computer Graphics applications as a faster computational alternative to subjective evaluation. Our metric can compare a video pair with arbitrary dynamic ranges, and comprises a human visual system model for a wide range of luminance levels, that predicts distortion visibility through models of luminance adaptation, spatiotemporal contrast sensitivity and visual masking. We present applications of the proposed metric to quality prediction of HDR video compression and temporal tone mapping, comparison of different rendering approaches and qualities, and assessing the impact of variable frame rate to perceived quality.

99 citations


Proceedings ArticleDOI
07 Jun 2010
TL;DR: This work presents a novel histogram reshaping technique which allows significantly more control than previous methods and shows for the first time that creative tone reproduction can be achieved by matching a high dynamic range image against a low dynamic range target.
Abstract: Image manipulation takes many forms. A powerful approach involves image adjustment by example. To make color edits more intuitive, the intelligent transfer of a user-specified target image's color palette can achieve a multitude of creative effects, provided the user is supplied with a small set of straightforward parameters. We present a novel histogram reshaping technique which allows significantly more control than previous methods. Given that the user is free to chose any image as the target, the process of steering the algorithm becomes artistic. Moreover, we show for the first time that creative tone reproduction can be achieved by matching a high dynamic range image against a low dynamic range target.

79 citations


Patent
01 Feb 2010
TL;DR: In this article, a localized operator is applied to the tone mapping compression factor which enhances apparent image contrast in the low dynamic range output of the tone map, and the algorithm is shown to improve the quality of tone mapping using the bilateral filter.
Abstract: Algorithms for improving the quality of images tone mapped using the bilateral filter are presented. The algorithms involve a localized operator applied to the tone mapping compression factor which enhances apparent image contrast in the low dynamic range output of the tone mapping. At least one embodiment of the present invention is related to circuitry configured to perform at least a portion of related calculations.

76 citations


Patent
29 Jun 2010
TL;DR: In this article, a high dynamic range image is segmented into different regions such that each region is represented by a matrix, where each element of the matrix is a weight or probability of a pixel.
Abstract: A method of tone mapping high dynamic range images for display on low dynamic range displays wherein a high dynamic range image is first accessed. The high dynamic range image is segmented into different regions such that each region is represented by a matrix, where each element of the matrix is a weight or probability of a pixel. An exposure of each region is determined or calculated and the exposure values are applied to the regions responsive to the weight or probability. The different regions are then fused together to obtain a final tone mapped image.

58 citations


Patent
Ralph Brunner1
25 May 2010
TL;DR: In this article, an apparatus, method, computer useable medium, and processor programmed to automatically generate tone mapping curves in a digital camera based on image metadata is described, and the tone mapping curve can be varied automatically based on the brightness histogram of the image.
Abstract: An apparatus, method, computer useable medium, and processor programmed to automatically generate tone mapping curves in a digital camera based on image metadata are described. Rather than having a static tone mapping curve for all images, the curve can be varied automatically based on, e.g., the brightness histogram of the image. In one embodiment, a certain percentage of the least bright pixels and a certain percentage of the brightest pixels can be disregarded, while the remaining pixels can be linearly stretched to encompass the original range of brightness values. Based on the distribution of the resultant stretched brightness histogram, slopes for the low end (S 0 ) and high end (S 1 ) of the tone mapping curve can be independently determined, and the tone mapping curve can be automatically generated. The improved, automatically generated tone mapping curve may be able to lift shadows more aggressively and/or increase the dynamic range of the image.

50 citations


Patent
15 Mar 2010
TL;DR: In this paper, an HDR signal processor is used to generate an HDR image from the pixel data S1 to S3, and performs tone mapping by multiplying this image data by the gain.
Abstract: An imaging control apparatus includes an HDR signal processor and a frame memory. The HDR signal processor obtains pixel data S1 and S2 obtained by imaging with a very short exposure time T1 and a short exposure time T2 earlier than obtaining pixel data S3 obtained by imaging with a normal exposure time T3, generates a luminance image data by separating illumination light component from the pixel data S1 and S2, the generation of the luminance image data starting when the pixel data S2 is obtained, and generates a gain for tone mapping from the luminance image data. On the other hand, the HDR signal processor generates an HDR image data from the pixel data S1 to S3, the generation of the HDR image starting when the pixel data S3 is obtained, and performs tone mapping by multiplying this image data by the gain.

47 citations


Patent
26 Feb 2010
TL;DR: In this article, a system for multi-modal mapping of images is described, where the image mapping system is used for visualizing high dynamic range images such as medical images, satellite images, high dynamic ranges photographs and the like and also for compressing such images.
Abstract: A system for multi-modal mapping of images is described. Embodiments are described where the image mapping system is used for visualizing high dynamic range images such as medical images, satellite images, high dynamic range photographs and the like and also for compressing such images. In examples, high bit-depth images are tone-mapped for display on equipment of lower bit-depth without loss of detail. In embodiments, the image mapping system computes statistics describing an input image and fits a multi-modal model to those statistics efficiently. In embodiments, the multi-modal model is a Gaussian mixture model and a plurality of sigmoid functions corresponding to the multi-modal model are obtained. In an embodiment the sigmoid functions are added to form a tone-mapping function which is used to transform a high bit-depth image such as 16 or 12 bits per pixel to a low bit-depth image such as 8 bits per pixel.

36 citations


Proceedings ArticleDOI
19 Jul 2010
TL;DR: A new tone map algorithm, derived from the Contrast Limited Adaptive Histogram Equalization (CLAHE) technique, is presented and the comparison between the obtained LDR images, and those produced by applying State of the Art TMOs proves how the main characteristic of the proposed algorithm is the ability to equally enhance visibility in both dark and bright areas.
Abstract: High Dynamic Range (HDR) images can represent the acquired scene with a greater dynamic range of luminance than classical Low Dynamic Range (LDR) ones. Despite the recent diffusion of some HDR camera models, HDR displays are not yet in the market. For this reason HDR images need to be adapted in order to be properly rendered through conventional devices. This operation mainly consists in a dynamic range compression realized by applying a Tone Mapping Operator (TMO). In this work, a new tone map algorithm, derived from the Contrast Limited Adaptive Histogram Equalization (CLAHE) technique, is presented. With respect to the original CLAHE, in the proposed implementation an adaptive contrast limit and a new strategy for the determination of local tone mapping functions have been introduced. The comparison between the obtained LDR images, and those produced by applying State of the Art TMOs, evidences how the main characteristic of the proposed algorithm is the ability to equally enhance visibility in both dark and bright areas. This could be, for example, a key feature in video surveillance applications and automotive safety camera systems.

Patent
08 Nov 2010
TL;DR: In this article, a technique for generating sharp, well-exposed, color images from low-light images is presented, where a series of underexposed images is acquired.
Abstract: A technique is provided for generating sharp, well-exposed, color images from low-light images. A series of under-exposed images is acquired. A mean image is computed and a sum image is generated each based on the series of under-exposed images. Chrominance variables of pixels of the mean image are mapped to chrominance variables of pixels of the sum image. Chrominance values of pixels within the series of under-exposed images are replaced with chrominance values of the sum image. A set of sharp, well-exposed, color images is generated based on the series of under-exposed images with replaced chrominance values.

Proceedings ArticleDOI
03 Dec 2010
TL;DR: The proposed technique invokes twice, in the first and the third stages, the well-known Non-Local Means method for spatial and temporal denoising: it is well adapted to the application, leading to the definition of a novel NLM tool.
Abstract: The paper presents a novel three-stage algorithm for very-low-light video denoising and enhancement. The proposed technique invokes twice, in the first and the third stages, the well-known Non-Local Means (NLM) method for spatial and temporal denoising: it is well adapted to the application, leading to the definition of a novel NLM tool. The intermediate stage performs a custom tone adjustment specifically aimed at enlarging the dynamic range of very dark videos. The overall approach transforms very dark videos into more watchable ones, effectively reduces very high noise, and all in all, produces high quality restored image sequences outperforming the recent state-of-the-art results. Additionally, the first and third stages can be combined as a two-step filtering scheme for normal-light videos: the novel denoising solution achieves a heavy noise removal, while reducing motion blur artifacts and preserving image details.

Patent
Peng Lin1
20 May 2010
TL;DR: In this article, a shape adaptive filter is used to separate the luminance signal into its illumination and reflectance components, contrast compression is applied to the illumination component, image sharpening can be applied to reflectance component, and the processed illumination and reflection components can be used to calculate a processed RGB signal.
Abstract: This is generally directed to systems and methods for local tone mapping of high dynamic range (“HDR”) images. For example, a HDR image can have its larger dynamic range mapped into the smaller dynamic range of a display device. In some embodiments, to perform the local tone mapping, a RGB to Y converter can be used to convert the input image signal to a luminance signal in the YCgCo color space, a shape adaptive filter can be used to separate the luminance signal into its illumination and reflectance components, contrast compression can be applied to the illumination component, image sharpening can be applied to the reflectance component, and the processed illumination and reflection components can be used to calculate a processed RGB signal. The dynamic range of the processed RGB signal can then be mapped into the dynamic range of the display device.

Journal ArticleDOI
TL;DR: Computer simulations with various sets of real, low dynamic range images show the effectiveness of the proposed tone mapping (TM) algorithm in terms of the visual quality as well the local contrast.
Abstract: In this paper, we propose a tone mapping (TM) method using color correction function (CCF) and image decomposition in high dynamic range (HDR) imaging. The CCF in the proposed TM is derived from the luminance compression function with the color constraint under which the color ratios, between the three color channels of the radiance map and dynamic range compression term, are preserved and color saturation is controlled. The proposed CCF is developed to locally perform the luminance compression and color saturation control in local TM. For image decomposition, we use a bilateral filter and apply the adaptive weight to the base layer of the luminance. Computer simulations with various sets of real, low dynamic range images show the effectiveness of the proposed TM algorithm in terms of the visual quality as well the local contrast. It can be used for contrast and color enhancement in various display and acquisition devices.

Journal ArticleDOI
TL;DR: The results illustrate that visual assessments obtained from the HDR display and those obtained from real‐world scenes are in good agreement, validating the potential for HDR display technology as an evaluation tool in this context.
Abstract: — Current HDR display technology approaches the dynamic-range capabilities of the fully adapted human visual system. As such, this technology has potential for performing as a surrogate for real-world scenes in the perceptual evaluation of high-dynamic-range (HDR) image-reproduction algorithms that aim to map HDR scenes to the limited dynamic ranges available in typical display and print technology. Compared with direct image assessment in comparison with real-world scenes, it is clear that use of HDR display technology has the benefit of simplicity in experimental design while maintaining the HDR of the original scene. To evaluate this potential application of HDR display technology, seven published versions of well-known HDR tone-mapping algorithms were benchmarked for perceptual rendering accuracy against each of four real-world scenes constructed in the laboratory and against corresponding images on an HDR display. The results illustrate that visual assessments obtained from the HDR display and those obtained from real-world scenes are in good agreement, validating the potential for HDR display technology as an evaluation tool in this context.

Proceedings ArticleDOI
03 Dec 2010
TL;DR: This paper proposes a new objective assessment algorithm that creates multi-scale similarity maps between HDR and LDR images and demonstrates how the proposed algorithm can be employed in an existing tone mapping algorithm for optimal parameter tuning.
Abstract: There has been a growing interest in recent years to develop tone mapping algorithms that can convert high dynamic range (HDR) to low dynamic range (LDR) images, so that they can be visualized on standard displays. With a number of tone mapping algorithms proposed, a natural question is which one gives the best performance. Although subjective assessment methods provide useful references, they are expensive and time-consuming, and are difficult to be embedded into the design stage of tone mapping algorithms for optimization and parameter tuning purposes. This paper focuses on objective assessment of tone mapping operators. Inspired by the success of the structural similarity index method for image quality assessment, we propose a new objective assessment algorithm that creates multi-scale similarity maps between HDR and LDR images. Our experiments show that the proposed method correlates well with subjective rankings of existing tone mapping operators. Furthermore, we demonstrate how the proposed algorithm can be employed in an existing tone mapping algorithm for optimal parameter tuning.

Journal ArticleDOI
TL;DR: A new tone mapping algorithm for enhancing image quality by deriving a spatially-variant operator for imitating S-potential response in human retina, which efficiently improves local contrasts while conserving good global appearance is proposed.
Abstract: There is a growing demand for being able to display high dynamic range (HDR) images on low dynamic range (LDR) devices. Tone mapping is a process for enhancing HDR image quality on an LDR device by converting the tonal values of the original image from HDR to LDR. This paper proposes a new tone mapping algorithm for enhancing image quality by deriving a spatially-variant operator for imitating S-potential response in human retina, which efficiently improves local contrasts while conserving good global appearance. The proposed tone mapping operator is studied from a system construction point of view. It is found that the operator is regarded as a natural extension of the Retinex algorithm by adding a global adaptation process to the local adaptation. The feasibility of the proposed algorithm is examined in detail on experiments using standard HDR images and real HDR scene images, comparing with conventional tone mapping algorithms.

Patent
Yuxiang Liu1, Wolfgang Schickler1, Leon Rosenshein1, David J. Simons1, Ido Omer1, Rob Ledner1 
31 Dec 2010
TL;DR: In this paper, a method for tone mapping a high-dynamic range image of a large terrestrial area into a lower dynamic range image uses a globally aware, locally adaptive approach whereby local tonal balancing parameter values are derived from known tone mapping parameters for a local 3×3 matrix of image tiles.
Abstract: A method for tone mapping a high dynamic range image of a large terrestrial area into a lower dynamic range image uses a globally aware, locally adaptive approach whereby local tonal balancing parameter values are derived from known tone mapping parameters for a local 3×3 matrix of image tiles and used in turn to derive a local sigmoid transfer function for pixels in the tile in the middle of the matrix. A global sigmoid transfer function is derived based on values of the tone mapping parameters applicable to the entire image. A lower dynamic range image pixel will have a local tone mapped value and a globally tone mapped value, which are combined by giving each a weighted value to provide a final low dynamitic range pixel value.

Journal ArticleDOI
TL;DR: It is shown that SSDs with limited size, resolution and colour depth require specific research to find or create an appropriate solution, and some characteristics of TMOs need to be emphasized to obtain better high‐fidelity mapped images for SSDs.
Abstract: In the last decade, an increasing number of techniques have been developed to reproduce high dynamic range imagery on traditional displays. These techniques, known as Tone Mapping Operators (TMOs), have been compared and ranked in different ways according to several image characteristics. However, none of these algorithms has been developed specifically for small screen devices (SSD). In this paper, we present an evaluation of currently used TMOs to show that SSDs with limited size, resolution and colour depth require specific research to find or create an appropriate solution. The research described in this paper is based on psychophysical experiments; using three different types of displays (CRT, LCD and SSD). The obtained results show that rankings obtained are similar for the LCD and CRT but are significantly different for the SSD. Furthermore, these rankings show additionally that some characteristics of TMOs need to be emphasized to obtain better high-fidelity mapped images for SSDs.

Proceedings ArticleDOI
03 Dec 2010
TL;DR: A threshold value for VDP is derived that indicates when two LDR images appear to have the same Quality of Experience, and it was found that the Visual Difference Predictor (VDP) outperforms the Structural Similarity Index and the Root Mean Square Error.
Abstract: High Dynamic Range (HDR) images are usually displayed on conventional Low Dynamic Range (LDR) displays because of the limited availability of HDR displays. For the conversion of the large dynamic luminance range into the eight bit quantized values, parameterized Tone Mapping Operators (TMO) are applied. Human observers are able to optimize the parameters in order to get the highest Quality of Experience by judging the displayed LDR images on a realism scale. In the study presented in this paper, two TMOs with three parameters each were evaluated by observers in a subjective experiment. Although the chosen parameter settings vary largely, the chosen images appear to have the same QoE for the observers. In order to assess this similarity objectively, three commonly used image quality measurement algorithms were applied. Their agreement with the preference of the observers was analyzed and it was found that the Visual Difference Predictor (VDP) outperforms the Structural Similarity Index and the Root Mean Square Error. A threshold value for VDP is derived that indicates when two LDR images appear to have the same Quality of Experience.

Journal ArticleDOI
26 Jul 2010
TL;DR: This work addresses several shortcomings of the widely used gradient magnitude-based edge strength model through the computation of a hypothetical Human Visual System response at edge locations, and suggests that simple perceptual models provide qualitative improvements on applications utilizing edge strength at the cost of a modest computational burden.
Abstract: Numerous image processing and computer graphics methods make use of either explicitly computed strength of image edges, or an implicit edge strength definition that is integrated into their algorithms. In both cases, the end result is highly affected by the computation of edge strength. We address several shortcomings of the widely used gradient magnitude-based edge strength model through the computation of a hypothetical Human Visual System (HVS) response at edge locations. Contrary to gradient magnitude, the resulting “visual significance” values account for various HVS mechanisms such as luminance adaptation and visual masking, and are scaled in perceptually linear units that are uniform across images. The visual significance computation is implemented in a fast multiscale second-generation wavelet framework which we use to demonstrate the differences in image retargeting, HDR image stitching, and tone mapping applications with respect to the gradient magnitude model. Our results suggest that simple perceptual models provide qualitative improvements on applications utilizing edge strength at the cost of a modest computational burden.

Proceedings Article
01 Jan 2010
TL;DR: Three different experimental protocols are proposed for assessing the applications of a display device used for psychovisual tests and selecting the most suitable TMO from six candidates, to give a first idea of the applications that can be addressed by this device.
Abstract: To identify people’s preference, psychovisual tests are carried out in virtual environment. Images of scenes used for psychovisual tests are natively High Dynamic Range (HDR) images. However, in order to allow a Low Dynamic Range (LDR) display device to project HDR pictures, their dynamic range must be compressed with a tone-mapping operator (TMO). Thus, before tests are carried out, selection of the most suitable TMO, perceptually speaking, is required to present images faithfully, depending on the aim of the application. In this paper, three different experimental protocols are proposed for assessing the applications of a display device used for psychovisual tests and selecting the most suitable TMO from six candidates. An additional goal is to give a first idea of the applications that can be addressed by this device. Two subjective experiments were conducted and are presented in the paper. The first one is divided in two steps. The results of three different protocols (two protocols in the first test and the third in the second test) for the identification of the preferred TMO for five different scenes are compared and LDR image defects noticed by observers are highlighted in the paper.

Journal ArticleDOI
TL;DR: This paper proposes a new method, based on a physical lighting model, to compute in real time a HDR illumination in virtual environments, which allows to re-use existing virtual environments as input, and computes HDR images in photometric units.
Abstract: Realistic images can be computed at interactive frame rates for Computer Graphics applications. Meanwhile, High Dynamic Range (HDR) rendering has a growing success in video games and virtual reality applications, as it improves the image quality and the player’s immersion feeling. In this paper, we propose a new method, based on a physical lighting model, to compute in real time a HDR illumination in virtual environments. Our method allows to re-use existing virtual environments as input, and computes HDR images in photometric units. Then, from these HDR images, displayable 8-bit images are rendered with a tone mapping operator and displayed on a standard display device. The HDR computation and the tone mapping are implemented in OpenSceneGraph with pixel shaders. The lighting model, together with a perceptual tone mapping, improves the perceptual realism of the rendered images at low cost. The method is illustrated with a practical application where the dynamic range of the virtual environment is a key rendering issue: night-time driving simulation.

Proceedings ArticleDOI
03 Aug 2010
TL;DR: A statistical model that approximates the mean square error (MSE) distortion resulting from the combined processes of tone-mapping and compression is developed and formulated to find the tone-curve that minimizes the expected MSE in the reconstructed HDR sequence.
Abstract: In this paper, we propose a real-time tone-mapping scheme for backward compatible high dynamic range (HDR) video compression. The appropriate choice of a tone-mapping operator (TMO) can significantly improve the HDR quality reconstructed from a low dynamic range (LDR) version. We develop a statistical model that approximates the mean square error (MSE) distortion resulting from the combined processes of tone-mapping and compression. Using this model, we formulate a numerical optimization problem to find the tone-curve that minimizes the expected MSE in the reconstructed HDR sequence. We then simplify the developed model in order to reduce the computational complexity of the optimization problem to a closed-form solution. Performance evaluations show that the proposed methods provide superior performance in terms of HDR MSE and SSIM compared to existing tone-mapping schemes. It is also shown that the LDR image quality resulting from the proposed methods matches that produced by perceptually-based TMOs.

Proceedings ArticleDOI
03 Dec 2010
TL;DR: This paper presents a new tone-mapping scheme that delivers superior compression efficiency while adhering to a predefined base layer perceptual quality, and proposes a technique with which to tone-map a high-bit-depth video directly in a compression-friendly color space without converting to the RGB domain.
Abstract: We develop a tone-mapping operator (TMO) that considers the perceptual quality of the tone-mapped image together with the compression efficiency. The proposed TMO is formulated as an optimization problem that incorporates statistical models of i) the quality of the tone-mapped image given a desired TMO, ii) the base layer bit-rate and iii) the enhancement layer bit-rate. The results show that our method achieves high coding gain while maintaining good quality tone-mapped images.

Proceedings ArticleDOI
12 Dec 2010
TL;DR: A novel bottom-up segmentation algorithm is developed through superpixel grouping which would enable us to detect scene changes and directly generate the ghost-free LDR image of the dynamic scene.
Abstract: High Dynamic Range (HDR) imaging requires one to composite multiple differently exposed images of a scene in the irradiance domain and perform tone mapping of the generated HDR image for displaying on Low Dynamic Range (LDR) devices. In the case of dynamic scenes, standard techniques may introduce artifacts called ghosts if the scene changes are not accounted for. In this paper, we consider the HDR problem for dynamic scenes. We develop a novel bottom-up segmentation algorithm through superpixel grouping which would enable us to detect scene changes. We then employ a piecewise patch-based compositing methodology to directly generate the ghost-free LDR image of the dynamic scene. The primary advantage of our approach is that we do not assume any knowledge of camera response function and exposure settings. Further, our approach performs well even in the case of significant scene changes.

Patent
01 Dec 2010
TL;DR: In this paper, a high dynamic range image tone mapping method based on a retina adaptive model was proposed, which consists of two-sided filtering on the logarithm domain luminance L(p) of each pixel p in the image.
Abstract: The invention discloses a high dynamic range image tone mapping method based on a retina adaptive model, which belongs to the field of digital image processing. The method comprises the following steps: (1) inputting a high dynamic range image; (2) acquiring the logarithm domain luminance L(p) of each pixel p in the image; (3) carrying out two-sided filtering on the logarithm domain luminance L(p) of each pixel p by using a two-sided filter, thereby obtaining the adaptive factor Aopl(p); (4) obtaining the luminance Lram(p) after carrying out nonlinear mapping on the logarithm domain luminance L(p) of each pixel p; (5) obtaining a red channel value I'(pR), a green channel value I'(pG) and a blue channel value I'(pB) after respectively carrying out nonlinear mapping on each pixel p in a red channel R, a green channel G and a blue channel B; and (6) constructing a new image file by using I'(pR), I'(pG) and I'(pB), thereby realizing the tone mapping of the high dynamic range image. The method simultaneously has the advantage of high speed in the global approach and the advantage of high capability of reserving image details in the partial approach.

Proceedings ArticleDOI
29 Nov 2010
TL;DR: The proposed algorithm combined color space decomposition and tone mapping based image brightness adjustment, which can improve the image contrast while maintaining the better color of the original image, and cannot increase noise.
Abstract: Illumination is an important factor to affect image quality in computer vision. In order to effectively weaken the influence of illumination on image quality, an image illumination correction algorithm based on tone mapping is proposed in this paper. The proposed algorithm combined color space decomposition and tone mapping based image brightness adjustment, which can improve the image contrast while maintaining the better color of the original image, and cannot increase noise. On the other hand, this algorithm is based on the pixel processing and does not need image transformation and image statistics information, which can reduce the computational complexity and more easily implement in hardware. Finally, a large number of experiments show that the proposed algorithm can effectively remove the impact of illumination and enhance image quality.

Patent
09 Feb 2010
TL;DR: In this article, a method and apparatus for bit depth scalable video encoding and decoding utilizing tone mapping and inverse tone mapping is described, which performs a conversion of the residue prediction from a residue domain to a pixel domain while maintaining the same bit depth representation.
Abstract: Methods and apparatus are provided for bit depth scalable video encoding and decoding utilizing tone mapping and inverse tone mapping. An apparatus includes an encoder (100) for encoding picture data for at least a portion of a picture by generating an inter-layer residue prediction for the portion using a tone mapping function and an inverse tone mapping function. The tone mapping function and the inverse tone mapping function perform a conversion of the inter-layer residue prediction from a residue domain to a pixel domain for bit depth scalability while maintaining a same bit depth representation.