scispace - formally typeset
Search or ask a question

Showing papers on "Channel (digital image) published in 2012"


Proceedings ArticleDOI
16 Jun 2012
TL;DR: A framework that measures patch rarities in each color space and combines them in a final map of all channels from both color systems is proposed, showing the significant advantage of this approach over 10 state-of-the-art saliency models.
Abstract: We introduce a saliency model based on two key ideas. The first one is considering local and global image patch rarities as two complementary processes. The second one is based on our observation that for different images, one of the RGB and Lab color spaces outperforms the other in saliency detection. We propose a framework that measures patch rarities in each color space and combines them in a final map. For each color channel, first, the input image is partitioned into non-overlapping patches and then each patch is represented by a vector of coefficients that linearly reconstruct it from a learned dictionary of patches from natural scenes. Next, two measures of saliency (Local and Global) are calculated and fused to indicate saliency of each patch. Local saliency is distinctiveness of a patch from its surrounding patches. Global saliency is the inverse of a patch's probability of happening over the entire image. The final saliency map is built by normalizing and fusing local and global saliency maps of all channels from both color systems. Extensive evaluation over four benchmark eye-tracking datasets shows the significant advantage of our approach over 10 state-of-the-art saliency models.

392 citations


Journal ArticleDOI
Hai Li1, Gang Lu1, Zongyou Yin1, Qiyuan He1, Hong Li1, Qing Zhang1, Hua Zhang1 
12 Mar 2012-Small
TL;DR: Using an optical imaging method combined with image analysis software, a high-contrast image of the MoS₂ sheets can be extracted from the red (R) channel of the color optical microscopy image.
Abstract: A simple approach is developed to identify the layer number of 2D MoS₂ sheets. By using an optical imaging method combined with image analysis software, a high-contrast image of the MoS₂ sheets can be extracted from the red (R) channel of the color optical microscopy image. The value of the intensity difference in the grayscale image of the R channel between MoS₂ sheets (1-3 layers) and the SiO₂ substrate can be used to identify the layer number of the sheet.

307 citations


Journal ArticleDOI
TL;DR: It is shown that the QZMs can be obtained from the conventional Zernike moments of each channel, and the theoretical framework to construct a set of combined invariants with respect to rotation, scaling and translation (RST) transformation is provided.

170 citations


Journal ArticleDOI
TL;DR: A couple-decoupled PRNU (CD-PRNU) extraction method is proposed, which first decomposes each color channel into four sub-images and then extracts the PRnU noise from each sub-image, to prevent the interpolation noise from propagating into the physical components, thus improving the accuracy of device identification and image content integrity verification.
Abstract: The last few years have seen the use of photo response non-uniformity noise (PRNU), a unique fingerprint of imaging sensors, in various digital forensic applications such as source device identification, content integrity verification, and authentication. However, the use of a color filter array for capturing only one of the three color components per pixel introduces color interpolation noise, while the existing methods for extracting PRNU provide no effective means for addressing this issue. Because the artificial colors obtained through the color interpolation process are not directly acquired from the scene by physical hardware, we expect that the PRNU extracted from the physical components, which are free from interpolation noise, should be more reliable than that from the artificial channels, which carry interpolation noise. Based on this assumption we propose a couple-decoupled PRNU (CD-PRNU) extraction method, which first decomposes each color channel into four sub-images and then extracts the PRNU noise from each sub-image. The PRNU noise patterns of the sub-images are then assembled to get the CD-PRNU. This new method can prevent the interpolation noise from propagating into the physical components, thus improving the accuracy of device identification and image content integrity verification.

112 citations


Journal ArticleDOI
TL;DR: An interior color-CT image reconstruction algorithm developed for this hybrid true-color micro-CT system is demonstrated, and a ``color diffusion'' phenomenon was observed whereby high-quality true- color images are produced not only inside the region of interest, but also in neighboring regions.
Abstract: X-ray micro-CT is an important imaging tool for biomedical researchers Our group has recently proposed a hybrid “true-color” micro-CT system to improve contrast resolution with lower system cost and radiation dose The system incorporates an energy-resolved photon-counting true-color detector into a conventional micro-CT configuration, and can be used for material decomposition In this paper, we demonstrate an interior color-CT image reconstruction algorithm developed for this hybrid true-color micro-CT system A compressive sensing-based statistical interior tomography method is employed to reconstruct each channel in the local spectral imaging chain, where the reconstructed global gray-scale image from the conventional imaging chain served as the initial guess Principal component analysis was used to map the spectral reconstructions into the color space The proposed algorithm was evaluated by numerical simulations, physical phantom experiments, and animal studies The results confirm the merits of the proposed algorithm, and demonstrate the feasibility of the hybrid true-color micro-CT system Additionally, a ``color diffusion'' phenomenon was observed whereby high-quality true-color images are produced not only inside the region of interest, but also in neighboring regions It appears harnessing that this phenomenon could potentially reduce the color detector size for a given ROI, further reducing system cost and radiation dose

97 citations


Proceedings ArticleDOI
28 Apr 2012
TL;DR: The main contribution is to alleviate a strict order constraint for color mapping based on human vision system, which enables the employment of a bimodal distribution to constrain spatial pixel difference and allows for automatic selection of suitable gray scale in order to preserve the original contrast.
Abstract: Decolorization - the process to transform a color image to a grayscale one - is a basic tool in digital printing, stylized black-and-white photography, and in many single channel image processing applications. In this paper, we propose an optimization approach aiming at maximally preserving the original color contrast. Our main contribution is to alleviate a strict order constraint for color mapping based on human vision system, which enables the employment of a bimodal distribution to constrain spatial pixel difference and allows for automatic selection of suitable gray scale in order to preserve the original contrast. Both the quantitative and qualitative evaluation bears out the effectiveness of the proposed method.

97 citations


Journal ArticleDOI
TL;DR: A content-aware algorithm is proposed that enhances dark images, sharpens edges, reveals details in textured regions, and preserves the smoothness of flat regions, which is an improvement over many existing methods.
Abstract: The current contrast enhancement algorithms occasionally result in artifacts, overenhancement, and unnatural effects in the processed images. These drawbacks increase for images taken under poor illumination conditions. In this paper, we propose a content-aware algorithm that enhances dark images, sharpens edges, reveals details in textured regions, and preserves the smoothness of flat regions. The algorithm produces an ad hoc transformation for each image, adapting the mapping functions to each image's characteristics to produce the maximum enhancement. We analyze the contrast of the image in the boundary and textured regions, and group the information with common characteristics. These groups model the relations within the image, from which we extract the transformation functions. The results are then adaptively mixed, by considering the human vision system characteristics, to boost the details in the image. Results show that the algorithm can automatically process a wide range of images—e.g., mixed shadow and bright areas, outdoor and indoor lighting, and face images—without introducing artifacts, which is an improvement over many existing methods.

93 citations


Journal ArticleDOI
Inhye Yoon1, Seonyung Kim1, Donggyun Kim1, Monson H. Hayes1, Joonki Paik1 
19 Mar 2012
TL;DR: The proposed image defogging algorithm with color correction in the HSV color space for video processing can significantly enhance the visibility of foggy video frames using the estimated atmospheric light and the modified transmission map.
Abstract: Consumer video surveillance systems often suffer from bad weather conditions, observed objects lose visibility and contrast due to the presence of atmospheric haze, fog, and smoke. In this paper, we present an image defogging algorithm with color correction in the HSV color space for video processing. We first generate a modified transmission map of the image segmentation using multiphase level set formulation from the intensity (V) values. We also estimate atmospheric light in the intensity (V) values. The proposed method can significantly enhance the visibility of foggy video frames using the estimated atmospheric light and the modified transmission map. Another contribution of the proposed work is the compensation of color distortion between consecutive frames using the temporal difference ratio of HSV color channels. Experimental results show that the proposed method can be applied to consumer video surveillance systems for removing atmospheric artifacts without color distortion.

64 citations


Book ChapterDOI
07 Oct 2012
TL;DR: This approach substantially improves depth accuracy over alternative single-shot coded-aperture designs, and since it avoids introducing additional spatial distortions and is light efficient, it allows high-quality deblurring and lower exposure times.
Abstract: We propose modifying the aperture of a conventional color camera so that the effective aperture size for one color channel is smaller than that for the other two. This produces an image where different color channels have different depths-of-field, and from this we can computationally recover scene depth, reconstruct an all-focus image and achieve synthetic re-focusing, all from a single shot. These capabilities are enabled by a spatio-spectral image model that encodes the statistical relationship between gradient profiles across color channels. This approach substantially improves depth accuracy over alternative single-shot coded-aperture designs, and since it avoids introducing additional spatial distortions and is light efficient, it allows high-quality deblurring and lower exposure times. We demonstrate these benefits with comparisons on synthetic data, as well as results on images captured with a prototype lens.

62 citations


Proceedings ArticleDOI
28 Nov 2012
TL;DR: A very fast and yet effective decolorization approach is proposed that is borne out by a new quantitative metric as well as qualitative comparisons with state-of-the-art methods.
Abstract: Decolorization -- the process to transform a color image to a grayscale one -- is a basic tool in digital printing, stylized black-and-white photography, and in many single channel image and video processing applications While recent research focuses on retaining meaningful visual features and color contrast, less attention has been paid to the complexity issue of the conversion Consequently, the resulting decolorization methods could be orders of magnitude slower than simple procedures, eg, Matlab built-in rgb2gray function, which could hamper them from being used practically In this paper, we propose a very fast and yet effective decolorization approach The effectiveness of the method is borne out by a new quantitative metric as well as qualitative comparisons with state-of-the-art methods

58 citations


Journal ArticleDOI
TL;DR: The performed analysis shows that the accuracy of the method is dependent on the face illumination but when considering home health care monitoring the proposed technique may be very useful due to its simplicity.
Abstract: In this paper a simple method of measuring the pulse rate is presented. Elaborated algorithm allows for efficient pulse rate registration directly from face images captured from a webcam. The desired signal is obtained by proper channel selection and principal component analysis. To determine the accuracy of the method an ECG signal is collected together with a video recordings. The effectiveness of the algorithm is considered for different regions of interest, several combinations of color channels and different lightening conditions. The time of principal components computation is compared with that obtained for independent component analysis. The performed analysis shows that the accuracy of the method is dependent on the face illumination but when considering home health care monitoring the proposed technique may be very useful due to its simplicity.

Journal ArticleDOI
TL;DR: A novel asymmetric color information cryptosystem based on an optical coherent superposition method and phase-truncated gyrator transform (GT) and two phase keys provide asymmetric keys that offer a high-level robustness against existing attacks is proposed.
Abstract: A novel asymmetric color information cryptosystem based on an optical coherent superposition method and phase-truncated gyrator transform (GT) is proposed. In this proposal, an original color image is converted into three independent channels, i.e., red, green, and blue. Each channel is separated into a random phase masks (RPM) and a key phase mask (KPM) using a coherent superposition method. The KPM is a modulation of the RPM by the color channel and used as decryption key. The same RPM, which is independent of plaintext, can be chosen for different images of the same size; however, KPMs, which are related to the original color images, are different. The RPM and the KPM are independently gyrator transformed. Then two gyrator spectra are, respectively, phase truncated to obtain two encoded images and amplitude truncated to generate two asymmetric phase keys. The KPM and two phase keys provide asymmetric keys. The transformation angles of the GT give additional keys for each channel and thus offer a high-level robustness against existing attacks. The proposed optical design is free from axial movement. Numerical simulations are demonstrated to verify the flexibility and effectiveness of the proposed method.

Patent
08 Feb 2012
TL;DR: In this paper, a tactile activation unit is driven to generate tactile feedback according to the index map generated by the binary image and the grayscale image, which includes a plurality of index values indicative of different strengths for tactile feedback.
Abstract: A method and an electronic device for tactile feedback are provided. An original image is input and converted to a binary image which includes a first grayscale value and a second grayscale value. The original image is converted to a grayscale image at least including a third grayscale value between the first grayscale value and the second grayscale value. An index map is generated according to the binary image and the grayscale image. The index map includes a plurality of index values indicative of different strengths for tactile feedback. A touch input on a touch panel is detected when the original image is displayed on a display panel. In response to the detected touch input, a tactile activation unit is driven to generate tactile feedback according to the index map.

Journal ArticleDOI
TL;DR: This paper proposes a maximum a posteriori estimation of the pattern of lost macroblocks, which assumes the knowledge of the decoded pixels only, which produces an accurate estimate of the mean-square-error (MSE) distortion introduced by channel errors.
Abstract: Video transmitted over an error-prone network may be received at the decoder with degradations due to packet losses. No-reference quality monitoring algorithms are the most practical way to measure the quality of the received video, since they do not impose any change with respect to the network architecture. Conventionally, these methods assume the availability of the corrupted bitstream. In some situations this is not possible, e.g., because the bitstream is encrypted or processed by third-party decoders, and only the decoded pixel values can be used. The major issue in this scenario is the lack of knowledge about which regions of the video have been actually lost, which is a fundamental ingredient for estimating channel-induced distortion. In this paper, we propose a maximum a posteriori estimation of the pattern of lost macroblocks, which assumes the knowledge of the decoded pixels only. This information can be used as input to a no-reference quality monitoring system, which produces an accurate estimate of the mean-square-error (MSE) distortion introduced by channel errors. The results of the proposed method are well correlated with the MSE distortion computed in full-reference mode, with a linear correlation coefficient equal to 0.9 at frame level and 0.98 at sequence level.

Posted Content
TL;DR: In this paper, the authors proposed an image steganography technique based on the Canny edge detection algorithm, which is designed to hide secret data into a digital image within the pixels that make up the boundaries of objects detected in the image.
Abstract: Steganography is the science of hiding digital information in such a way that no one can suspect its existence. Unlike cryptography which may arouse suspicions, steganography is a stealthy method that enables data communication in total secrecy. Steganography has many requirements, the foremost one is irrecoverability which refers to how hard it is for someone apart from the original communicating parties to detect and recover the hidden data out of the secret communication. A good strategy to guaranteeirrecoverability is to cover the secret data not usinga trivial method based on a predictable algorithm, but using a specific random pattern based on a mathematical algorithm. This paper proposes an image steganography technique based on theCanny edge detection algorithm.It is designed to hide secret data into a digital image within the pixels that make up the boundaries of objects detected in the image. More specifically, bits of the secret data replace the three LSBs of every color channel of the pixels detected by the Canny edge detection algorithm as part of the edges in the carrier image. Besides, the algorithm is parameterized by three parameters: The size of the Gaussian filter, a low threshold value, and a high threshold value. These parameters can yield to different outputs for the same input image and secret data. As a result, discovering the inner-workings of the algorithm would be considerably ambiguous, misguiding steganalysts from the exact location of the covert data. Experiments showed a simulation tool codenamed GhostBit, meant to cover and uncover secret data using the proposed algorithm. As future work, examining how other image processing techniques such as brightness and contrast adjustment can be taken advantage of in steganography with the purpose ofgiving the communicating parties more preferences tomanipulate their secret communication.

Journal ArticleDOI
TL;DR: The ability of this three-channel rigid endoscope system for measuring blood perfusion changes in the tissue during surgery and its potential use as a platform for other sequential imaging modalities are demonstrated.
Abstract: Sequential multispectral imaging is an acquisition technique that involves collecting images of a target at different wavelengths, to compile a spectrum for each pixel In surgical applications it suffers from low illumination levels and motion artefacts A three-channel rigid endoscope system has been developed that allows simultaneous recording of stereoscopic and multispectral images Salient features on the tissue surface may be tracked during the acquisition in the stereo cameras and, using multiple camera triangulation techniques, this information used to align the multispectral images automatically even though the tissue or camera is moving This paper describes a detailed validation of the set-up in a controlled experiment before presenting the first in vivo use of the device in a porcine minimally invasive surgical procedure Multispectral images of the large bowel were acquired and used to extract the relative concentration of haemoglobin in the tissue despite motion due to breathing during the acquisition Using the stereoscopic information it was also possible to overlay the multispectral information on the reconstructed 3D surface This experiment demonstrates the ability of this system for measuring blood perfusion changes in the tissue during surgery and its potential use as a platform for other sequential imaging modalities

Journal ArticleDOI
TL;DR: An image steganography technique based on the Canny edge detection algorithm that is designed to hide secret data into a digital image within the pixels that make up the boundaries of objects detected in the image.
Abstract: is the science of hiding digital information in such a way that no one can suspect its existence. Unlike cryptography which may arouse suspicions, steganography is a stealthy method that enables data communication in total secrecy. Steganography has many requirements, the foremost one is irrecoverability which refers to how hard it is for someone apart from the original communicating parties to detect and recover the hidden data out of the secret communication. A good strategy to guaranteeirrecoverability is to cover the secret data not usinga trivial method based on a predictable algorithm, but using a specific random pattern based on a mathematical algorithm. This paper proposes an image steganography technique based on theCanny edge detection algorithm.It is designed to hide secret data into a digital image within the pixels that make up the boundaries of objects detected in the image. More specifically, bits of the secret data replace the three LSBs of every color channel of the pixels detected by the Canny edge detection algorithm as part of the edges in the carrier image. Besides, the algorithm is parameterized by three parameters: The size of the Gaussian filter, a low threshold value, and a high threshold value. These parameters can yield to different outputs for the same input image and secret data. As a result, discovering the inner- workings of the algorithm would be considerably ambiguous, misguiding steganalysts from the exact location of the covert data. Experiments showed a simulation tool codenamed GhostBit, meant to cover and uncover secret data using the proposed algorithm. As future work, examining how other image processing techniques such as brightness and contrast adjustment can be taken advantage of in steganography with the purpose ofgiving the communicating parties more preferences tomanipulate their secret communication.

Proceedings ArticleDOI
17 Nov 2012
TL;DR: The algorithm is mainly to estimate the median function in the use of the media filtering method based on the dark channel to make the media function more accurate and combine with the wiener filtering closer, so that the fog image restoration problem is transformed into an optimization problem, and by minimizing mean-square error a clearer, fogless image is finally obtained.
Abstract: If we use the image haze removal of dark channel prior, we're prone to color distortion phenomenon for some large white bright area in the image. Aimed at these problems, this paper presents an image haze removal of wiener filtering based on dark channel prior. The algorithm is mainly to estimate the median function in the use of the media filtering method based on the dark channel, to make the media function more accurate and combine with the wiener filtering closer. So that the fog image restoration problem is transformed into an optimization problem, and by minimizing mean-square error a clearer, fogless image is finally obtained. Experimental results show that the proposed algorithm can make the image more detailed, the contour smoother and the whole image clearer. In particular, this algorithm can recover the contrast of a large white area fog image. The algorithm not only compensates for the lack of dark channel prior algorithm, but also expands the application of dark channel prior algorithm and shortens the running time of the image algorithm.


Proceedings ArticleDOI
01 Dec 2012
TL;DR: This work proposes a simple but effective method to remove haze from a single remote sensing image based on the dark channel prior and a common haze imaging model and uses a low-pass Gaussian filter to refine the coarse estimated atmospheric veil.
Abstract: Remote sensing images are widely used in various fields. However, they always suffer from the bad weather conditions which also affect their sufficient usage. In order to solve this problem, we propose a simple but effective method to remove haze from a single remote sensing image. Our work is based on the dark channel prior and a common haze imaging model. To eliminate artifacts, we use a low-pass Gaussian filter to refine the coarse estimated atmospheric veil. The experimental results show that our approach achieves good results with very little processing time.

Patent
10 May 2012
TL;DR: In this article, a projection display comprising an imaging unit is described, said unit being designed to generate individual images in a distribution, such as a two-dimensional distribution, of partial regions of an imaging plane of the imaging unit, and a multi-channel optical unit, which is configured to image per channel in each case an assigned individual image or an assigned partial region of the image unit, to be precise such that the imaging of the individual image in a projection surface is at least partly superimposed to form a total image.
Abstract: A projection display comprising an imaging unit is described, said imaging unit being designed to generate individual images in a distribution, such as e.g. a two-dimensional distribution, of partial regions of an imaging plane of the imaging unit, and a multi-channel optical unit, which is configured to image per channel in each case an assigned individual image or an assigned partial region of the imaging unit, to be precise such that the imaging of the individual images in a projection surface is at least partly superimposed to form a total image, wherein the projection surface is a non-planar freeform surface, such as e.g. a curved surface, and/or is tilted relative to the imaging plane, and the imaging unit is designed in such a way that constellations of points in the partial images which are respectively superimposed by the multi-channel optical unit in a respective common point in the total image differ depending on the distance between the respective common point in the total image and the multi-channel optical unit. Alternatively, imaging unit and multi-channel optical unit are designed in such a way that a manifestation of a contribution of each channel to the total image varies locally across the total image depending on the distance between the respective common point in the total image and the multi-channel optical unit.

Patent
17 Jan 2012
TL;DR: In this paper, the chroma variations in at least a red channel occur with an oscillation frequency and amplitude consistent with changes due to a pulse or heartbeat, and the variations can be analyzed to determine whether the captured image information likely corresponds to an actual human user instead of a representation (e.g., photo) of a human user.
Abstract: A user of a computing device can be authenticated using image information captured by at least one camera of the computing device. In addition to analyzing the image information using a facial recognition algorithm, for example, variations in color of a portion of the captured image information corresponding to a user's face can be monitored over a period of time. The variations can be analyzed to determine whether the captured image information likely corresponds to an actual human user instead of a representation (e.g., photo) of a human user, such as where the chroma variations in at least a red channel occur with an oscillation frequency and amplitude consistent with changes due to a pulse or heartbeat.

Patent
28 Mar 2012
TL;DR: In this article, a video compressing and encoding method with an alpha transparent channel is proposed, where the acquired video image is transmitted to the image in the format of RGB or YUV 4:4:4/YUV4:2:2 /YUV 4 :2:0, and the compressed data of the alpha transparent channels and the original video is stored in the same file.
Abstract: The invention relates to a video compressing and encoding method with an alpha transparent channel, comprising the following steps of: inverting the acquired video image to the image in the format of RGB or YUV4:4:4/YUV4:2:2/YUV4:2:0; compressing the acquired data in the alpha transparent channel in a no-damage mode; encoding and compressing video data for the video image in the specific format according to the frame format of MPEG-2 I and saving the compressed data in the alpha transparent channel in the compressed data structure of the video image. The method realizes the encoding of a specific video picture, can use a standard MPEG2 encoder for encoding, and effectively reduces video bitrate when ensuring the high quality of the video so as to realize the video data encoding with high quality, high efficiency and low cost. Because the data of the alpha transparent channel and the compressed data of the video image are saved in the same file, the video compressing and encoding method not only simplifies the process of processing the image at the later period and the information sharing between file management and a program, but also reserves the original video which is not added with the data of the alpha transparent channel.

Patent
24 Oct 2012
TL;DR: In this paper, a video image defogging method based on self-adapting allowance is proposed for outdoor monitoring, remote sensing, intelligent transportation and other aspects, which is applicable to video images with basically unchanged scenes.
Abstract: The invention relates to a video image defogging method based on self-adapting allowance and belongs to the field of video image processing. The method includes: building a single-frame image foggy day degradation model, estimating a rough transmission picture by aid of dark channel prior, obtaining a refined transmission by aid of a guide filter, judging whether images contain a large bright area, obtaining the rectified transmission picture and restoring a fog-free image. The method is applicable to video images with basically unchanged scenes like vide monitoring and video images with dynamically changing scenes, and can be widely applied to outdoor monitoring, remote sensing, intelligent transportation and other aspects.

Journal ArticleDOI
TL;DR: This work explores the use of complexity estimates to predict the aesthetic merit of photographs, using a set of image metrics and two different classifiers to classify images gathered from a photography web site.
Abstract: In recent years, the search for computational systems that classify images based on aesthetic properties has gained momentum. Such systems have a wide range of potential applications, including image search, organization, acquisition and generation. This work explores the use of complexity estimates to predict the aesthetic merit of photographs. We use a set of image metrics and two different classifiers. Our approach classifies images gathered from a photography web site, attempting to reproduce the evaluation made by a group of users. For this purpose, we use complexity estimate metrics based on the encoding size and compression error of JPEG and fractal compression, which are applied to the original value channel and to the images resulting from applying Sobel and Canny filters to this channel. By employing these estimates, in conjunction with the average and standard deviation of the value channel, i.e., 20 features, a success rate of 74.59% was attained. Using the three most influential features yiel...

Proceedings ArticleDOI
01 Aug 2012
TL;DR: A novel single image-based dehazing framework is proposed to remove haze effects from image/video, where two novel image priors are proposed, called the pixel-based dark channel prior and the pixel -based bright channel prior, to accurately estimate the atmospheric light via haze density analysis.
Abstract: Images/videos of outdoor scenes are usually degraded by the turbid medium in the atmosphere. In this paper, a novel single image-based dehazing framework is proposed to remove haze effects from image/video, where we propose two novel image priors, called the pixel-based dark channel prior and the pixel-based bright channel prior. Based on the two priors with the haze imaging model, we propose to accurately estimate the atmospheric light via haze density analysis. We can then accurately estimate the transmission map, followed by refining it via the bilateral filter. As a result, high-quality haze-free image can be recovered with lower computational complexity, which can be naturally extended to video dehazing.

Journal ArticleDOI
TL;DR: The experimental results show that the range of colors that can be measured and that shape and color information of colorful objects can be reliably obtained, and there is no crosstalk between color channels during phase calculation by phase-shifting algorithm.
Abstract: A novel method is presented to simultaneously measure shape and color information of artifacts containing color features. The technique operates by projecting composite red, green, and blue fringe patterns onto the surface of colorful objects. Theoretical analysis proves that there is no crosstalk between color channels during phase calculation by phase-shifting algorithm when three fringe patterns with the same fringe number are coded into red, green, and blue channels to form a composite RGB fringe pattern image. The color channel giving the maximum modulation depth at each pixel is used to measure shape information. Since three color channels are used, color information of the object surface can be extracted with high dynamic range from the same fringe pattern images. Using the recently developed color fringe projection system, composite RGB fringe patterns are projected onto colorful objects to test the proposed method. The experimental results show that the range of colors that can be measured and that shape and color information of colorful objects can be reliably obtained.

Proceedings ArticleDOI
20 May 2012
TL;DR: Experimental results demonstrate that the new haze-removing method is properly applied to various dense and distribution haze images without sacrificing color naturalness by using refined Dark Channel Prior (DCP) and adding post processing.
Abstract: Removing haze technique is an important and necessary procedure to avoid ill-condition visibility of human eyes. To improve the dehazing quality, a new haze-removing method is proposed in this paper. Specifically, this method can be properly applied to various dense and distribution haze images without sacrificing color naturalness by using refined Dark Channel Prior(DCP) and adding post processing. Experimental results demonstrate that the new method provides higher dehazing quality and color naturalness than other existing techniques.

Proceedings ArticleDOI
01 Dec 2012
TL;DR: An improved dark channel prior based algorithm is devised to dehaze the reflex lightness image and the exposure adjustment is estimated from the ambience illumination image, and a high quality haze- free image is produced by refining the brightness of the preliminarily dehazed image with the estimated exposure adjustment.
Abstract: Single image dehazing has been a challenging prob- lem due to its ill-posed nature. While most of the existing single image based dehazing algorithms address this issue by introduc- ing certain assumptions and priors into the haze imaging model, the imaging process of imaging devices has been seldom taken into account, such as white balance and metering. In general, consumer photos are taken with AWB (Auto White Balance). Hence, color temperature in a foggy scenario may not be correctly detected, which results in color distortion; and the whole scene looks brighter, which leads to under-exposure during the imaging process. In this paper, we propose to handle these two issues by applying white balance correction and decomposing an image into two component images, reflex lightness image and ambience illumination image. We devise an improved dark channel prior based algorithm to dehaze the reflex lightness image and the exposure adjustment is estimated from the ambience illumination image. Finally, a high quality haze- free image is produced by refining the brightness of the preliminarily dehazed image with the estimated exposure adjustment. Experimental results with a benchmark dataset demonstrate that our approach outperforms the state-of-the-art, in terms of contrast and color fidelity.

Journal ArticleDOI
Wenxuan Shi1, Jie Li1
TL;DR: A new algorithm by which shadows are extracted from a single color aerial image is presented, which presents better shadow detection accuracy in the images that contain some dark green lawn, river, or low brightness shadow regions.
Abstract: Many problems in image processing and computer vision arise from shadows in a single color aerial image. This article presents a new algorithm by which shadows are extracted from a single color aerial image. Apart from using the ratio value of the hue over the intensity in some state-of-the-art algorithms, this article introduces another ratio map, which is obtained by applying the saturation over the intensity. Candidate shadow and nonshadow regions are separated by applying Otus’s thresholding method. The color attenuation relationship that describes the relationship between the attenuation of each color channel is derived from the Planck’s blackbody irradiance law. For each region, the color attenuation relationship and other determination conditions are performed iteratively to segment it into smaller sub-regions and to identify whether each sub-region is a true shadow region. Compared with previous methods, the proposed algorithm presents better shadow detection accuracy in the images that contain some dark green lawn, river, or low brightness shadow regions. The experimental results demonstrate the advantage of the proposed algorithm.