Noise-enhanced contrast stretching of dark images in SVD-DWT domain
01 Dec 2013-pp 1-6
TL;DR: A noise-enhanced contrast stretching algorithm for enhancement of dark images in SVD-DWT domain has been presented and comparison with other SR-based and non-SR based algorithms shows noteworthy performance of the algorithm.
Abstract: A noise-enhanced contrast stretching algorithm for enhancement of dark images in SVD-DWT domain has been presented in this paper. A dark or low-contrast image is considered to be comprising a weak signal (information) and noise (due to insufficient illumination). Since singular values of an image represent luminance of independent image layers, the internal noise may be considered to be inherent in the singular values of the image, as well that of the wavelet approximation coefficients of a dark image. The singular values of the approximation coefficients are iteratively processed using the analogy of a double-well system exhibiting dynamic stochastic resonance (SR), where addition of noise is utilized to enhance system performance. Iteration is terminated with the criterion of target contrast and visual qualities. Comparison with other SR-based and non-SR based algorithms shows noteworthy performance of the algorithm in the SVD-DWT domain.
Citations
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TL;DR: The proposed noise-enhanced iterative processing on Fourier coefficients for enhancement of low-contrast images has been found to give noteworthy performance for both low- Contrast and dark images among the SR-based techniques and is found to be better than most of the non-SR- based techniques, in terms of contrast enhancement, perceptual quality and colorfulness.
Abstract: This paper presents a study of noise-enhanced iterative processing on Fourier coefficients for enhancement of low-contrast images. The processing equation is derived from the concept of dynamic stochastic resonance (SR), where the presence of optimum amount of noise produces an improved performance in the system. Similar to our earlier works on SR-based contrast enhancement, noise in the current context is the internal noise inherent in an image due to insufficient illumination. Here, however, the parameter selection is done so as to achieve large noise suppression. Iteration is terminated when target performance has been achieved. It is observed that the increase in the variance of the Fourier magnitude distribution leads to an increase in the contrast of the image. The increase in the variance is analytically proven to be equivalent to the process of coefficient rooting. Comparison has been made with various state-of-the-art SR and non-SR-based techniques in spatial/frequency domains. The proposed technique has been found to give noteworthy performance for both low-contrast and dark images among the SR-based techniques. The performance is also found to be better than most of the non-SR-based techniques, in terms of contrast enhancement, perceptual quality and colorfulness.
12 citations
TL;DR: An extensive literature review was conducted and the nighttime visual refinement approaches into nighttime restoration and enhancement were classified and identified the research gap fields to explore future research directions in nighttime visual enhancement techniques.
Abstract: Video surveillance systems substitute manual efforts in various safety critic domains such as border area, assisted living, banking, service stations, and transportation. The multimedia-based surveillance system has a significant role in security and forensic systems because people tend to be easily convinced after observing voice, image, and video. Hence, these videos are strong evidence in the forensic investigation. However, most of the criminal activities such as ATM robbery and assassination are occur at nighttime because of the crime supporting dark environment. Many of the night surveillance systems in military, as well as commercial applications, are equipped with infrared and thermal based night vision systems. Its poor capability of texture and color interpretations are the major issues to ensure secure nighttime video monitoring. Specifically, visual refinements of nighttime surroundings and foreground objects provide a valuable assistance in the nighttime security system. In this scenario, it is highly recommended a review of the state-of-the-art nighttime visual refinement approaches. We conducted an extensive literature review and classified the nighttime visual refinement approaches into nighttime restoration and enhancement. This comparative literary analysis identified the research gap fields to explore future research directions in nighttime visual enhancement techniques. Finally, we discussed various open issues and future directions in the context enhancement based nighttime enhancement research.
8 citations
TL;DR: It can be inferred from comparative analysis with respect to other conventional methods that while the algorithm is observed to work well in all three hybrid domains, the SV-DCT domain performs better in terms of iteration count, while DCT-DWT is found to outperform others in Terms of perceptual quality.
Abstract: This paper aims to present an analysis of a noise-aided contrast enhancement algorithm in hybrid transform domains. The performance of our earlier noise-enhanced iterative algorithm, formulated from the motion dynamics of a double-well system exhibiting dynamic stochastic resonance, has been investigated here on hybrid coefficients, viz. singular values (SVs) of wavelet coefficients, SVs of discrete cosine transform (DCT) coefficients, and DCT of wavelet coefficients, of a dark image. The performance of the algorithm is gauged using metrics indicating relative contrast enhancement and perceptual quality. Colorfulness, subjective visual scores and logarithmic contrast metrics for outputs are also observed. Experimental results display noteworthy enhancement of contrast on both natural and synthetically-darkened images. It can be inferred from comparative analysis with respect to other conventional methods that while the algorithm is observed to work well in all three hybrid domains, the SV-DCT domain performs better in terms of iteration count, while DCT-DWT is found to outperform others in terms of perceptual quality.
4 citations
References
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TL;DR: It is shown that, far from being a drawback, the ubiquitous presence of random vibrations in vision systems operating from mobile devices can advantageously be used as a fundamental tool for edge detection.
Abstract: We show that, far from being a drawback, the ubiquitous presence of random vibrations in vision systems operating from mobile devices can advantageously be used as a fundamental tool for edge detection. Directly inspired by biology, the concept of dynamic retina uses the random spatiotemporal path, traced by a moving receptor that samples the image over time, as the basis for the edge detection operation. We propose a simple mathematical formalization of the dynamic retina concept that shows that the relevant information needed for edge detection is contained in the modulation of the variance of the output signal delivered by the retina. Based on a sequence of observations, we then use a variance estimator to determine the presence of the image edges. Following again a biological inspiration, more specifically focusing on neuron dynamics, we introduce a threshold type estimator and use its local asymptotic normality to optimize, via the Cramer-Rao relation, the value of the threshold. The optimal threshold value coincides with a maximum of the associated Fisher information and the overall process can therefore be directly interpreted as a stochastic resonance. We end our contribution by reporting some simple experimental illustrations.
141 citations
"Noise-enhanced contrast stretching ..." refers background in this paper
...The concept of ‘stochastic resonance’, where noise is utilized to amplify a weak subthreshold signal, has particularly been found to work remarkably in contrast enhancement of dark and low-contrast images [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]....
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TL;DR: It is shown that the best transforms for transform image coding, namely, the scrambled real discrete Fourier transform, the discrete cosine transform, and the discrete Cosine-III transform are also the best for image enhancement.
Abstract: Blockwise transform image enhancement techniques are discussed. Previously, transform image enhancement has usually been based on the discrete Fourier transform (DFT) applied to the whole image. Two major drawbacks with the DFT are high complexity of implementation involving complex multiplications and additions, with intermediate results being complex numbers, and the creation of severe block effects if image enhancement is done blockwise. In addition, the quality of enhancement is not very satisfactory. It is shown that the best transforms for transform image coding, namely, the scrambled real discrete Fourier transform, the discrete cosine transform, and the discrete cosine-III transform, are also the best for image enhancement. Three techniques of enhancement discussed in detail are alpha-rooting, modified unsharp masking, and filtering motivated by the human visual system response (HVS). With proper modifications, it is observed that unsharp masking and HVS-motivated filtering without nonlinearities are basically equivalent. Block effects are completely removed by using an overlap-save technique in addition to the best transform.
129 citations
"Noise-enhanced contrast stretching ..." refers methods in this paper
...Comparative analysis with non-SR-based techniques, like contrast limited adaptive histogram equalization (CLAHE) [13], gamma correction (Gamma), single-scale retinex (Retinex) [14], multi-scale retinex (MSR) [15], and modified high-pass filtering (MHPF) [16], alpha rooting (AR) [17], multicontrast enhancement (MCE) [18], MCE with dynamic-range compression (MCE-DRC) [29], and color enhancement using scaling (CES) [19] has been performed....
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...A popular technique called alpharooting [17] produces an increase in contrast of the image when the magnitude of each transform coefficient is raised to a power a, 0 < a < 1, and the sign or the phase of the coefficient is unchanged....
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TL;DR: This paper discusses color image quality metrics and presents no-reference artifact metrics for blockiness, blurriness, and colorfulness, showing that these metrics are highly correlated with experimental data collected through subjective experiments.
Abstract: Color image quality depends on many factors, such as the initial capture system and its color image processing, compression, transmission, the output device, media and associated viewing conditions. In this paper, we are primarily concerned with color image quality in relation to compression and transmission. We review the typical visual artifacts that occur due to high compression ratios and/or transmission errors. We discuss color image quality metrics and present no-reference artifact metrics for blockiness, blurriness, and colorfulness. We show that these metrics are highly correlated with experimental data collected through subjective experiments. We use them for no-reference video quality assessment in different compression and transmission scenarios and again obtain very good results. We conclude by discussing the important effects viewing conditions can have on image quality.
116 citations
"Noise-enhanced contrast stretching ..." refers methods in this paper
...To observe the colorfulness of the enhanced image, we have used a no-reference metric called colorfulness metric, (CM ) [27]....
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TL;DR: The proposed stochastic resonance (SR)-based transform in Fourier space for the enhancement of magnetic resonance images of brain lesions can restore the original image from noisy image and optimally enhance the edges or boundaries of the tissues, and enables improved diagnosis over conventional methods.
Abstract: Objective In general, low-field MRI scanners such as the 0.5- and 1-T ones produce images that are poor in quality. The motivation of this study was to lessen the noise and enhance the signal such that the image quality is improved. Here, we propose a new approach using stochastic resonance (SR)-based transform in Fourier space for the enhancement of magnetic resonance images of brain lesions, by utilizing an optimized level of Gaussian fluctuation that maximizes signal-to-noise ratio (SNR). Materials and Methods We acquired the T1-weighted MR image of the brain in DICOM format. We processed the original MR image using the proposed SR procedure. We then tested our approach on about 60 patients of different age groups with different lesions, such as arteriovenous malformation, benign lesion and malignant tumor, and illustrated the image enhancement by using just-noticeable difference visually as well as by utilizing the relative enhancement factor quantitatively. Results Our method can restore the original image from noisy image and optimally enhance the edges or boundaries of the tissues, clarify indistinct structural brain lesions without producing ringing artifacts, as well as delineate the edematous area, active tumor zone, lesion heterogeneity or morphology, and vascular abnormality. The proposed technique improves the enhancement factor better than the conventional techniques like the Wiener- and wavelet-based procedures. Conclusions The proposed method can readily enhance the image fusing a unique constructive interaction of noise and signal, and enables improved diagnosis over conventional methods. The approach well illustrates the novel potential of using a small amount of Gaussian noise to improve the image quality.
108 citations
"Noise-enhanced contrast stretching ..." refers background in this paper
...The concept of ‘stochastic resonance’, where noise is utilized to amplify a weak subthreshold signal, has particularly been found to work remarkably in contrast enhancement of dark and low-contrast images [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]....
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...Metric of contrast enhancement (F ) is based on global variance and mean of original and enhanced images [6]....
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TL;DR: The internal noise of an image has been utilised to produce a noise-induced transition of a dark image from a state of low contrast to that of high contrast.
Abstract: In this study, a dynamic stochastic resonance (DSR)-based technique in spatial domain has been proposed for the enhancement of dark- and low-contrast images. Stochastic resonance (SR) is a phenomenon in which the performance of a system (low-contrast image) can be improved by addition of noise. However, in the proposed work, the internal noise of an image has been utilised to produce a noise-induced transition of a dark image from a state of low contrast to that of high contrast. DSR is applied in an iterative fashion by correlating the bistable system parameters of a double-well potential with the intensity values of a low-contrast image. Optimum output is ensured by adaptive computation of performance metrics - relative contrast enhancement factor ( F ), perceptual quality measures and colour enhancement factor. When compared with the existing enhancement techniques such as adaptive histogram equalisation, gamma correction, single-scale retinex, multi-scale retinex, modified high-pass filtering, edge-preserving multi-scale decomposition and automatic controls of popular imaging tools, the proposed technique gives significant performance in terms of contrast and colour enhancement as well as perceptual quality. Comparison with a spatial domain SR-based technique has also been illustrated.
88 citations
"Noise-enhanced contrast stretching ..." refers background or methods in this paper
...For a visual comparison among various techniques, readers are advised to refer to [9], [11], [12]....
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...Readers are advised to refer to [9], [12] for a exhaustive mathematical formulation of the same in SVD and intensity domains respectively....
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...The concept of ‘stochastic resonance’, where noise is utilized to amplify a weak subthreshold signal, has particularly been found to work remarkably in contrast enhancement of dark and low-contrast images [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]....
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...Eq 1, when discretized for this bistable double-well (as described in [9], [12]), produces the following iterative equation:...
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