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Contourlet

About: Contourlet is a research topic. Over the lifetime, 3533 publications have been published within this topic receiving 38980 citations.


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Journal ArticleDOI
TL;DR: An over-complete multiscale decomposition is presented by combining the Laplacian pyramid and the complex directional filter bank (DFB) and the proposed transform possesses several desirable properties including multiresolution, arbitrarily high directional resolution, low redundant ratio, and efficient implementation.
Abstract: This paper presents an over-complete multiscale decomposition by combining the Laplacian pyramid and the complex directional filter bank (DFB). The filter bank is constructed in such a way that each complex directional filter is analytical using the dual-tree structure of real fan filters. Necessary and sufficient conditions in order for the resulting multirate filter bank to be shift-invariant in energy sense (shiftability) are derived in terms of the magnitude and phase responses of these filters. Their connection to 2D Hilbert transform relationship is established. The proposed transform possesses several desirable properties including multiresolution, arbitrarily high directional resolution, low redundant ratio, and efficient implementation.

63 citations

Journal ArticleDOI
TL;DR: A novel CBIR scheme that abstracts each image in the database in terms of statistical features computed using the Multi-scale Geometric Analysis of Non-subsampled Contourlet Transform (NSCT) and incorporates a Relevance Feedback mechanism that uses a graph-theoretic approach to rank the images in accordance with the user's feedback.
Abstract: Content-Based Image Retrieval (CBIR) is an important problem in the domain of digital data management. There is indeed a growing availability of images, but unfortunately the traditional metadata-based search systems are unable to properly exploit their visual information content. In this article we introduce a novel CBIR scheme that abstracts each image in the database in terms of statistical features computed using the Multi-scale Geometric Analysis (MGA) of Non-subsampled Contourlet Transform (NSCT). Noise resilience is one of the main advantages of this feature representation. To improve the retrieval performance and reduce the semantic gap, our system incorporates a Relevance Feedback (RF) mechanism that uses a graph-theoretic approach to rank the images in accordance with the user's feedback. First, a graph of images is constructed with edges reflecting the similarity of pairs of images with respect to the proposed feature representation. Then, images are ranked at each feedback round in terms of the probability that a random walk on this graph reaches an image tagged as relevant by the user before hitting a non-relevant one. Experimental analyses on three different databases show the effectiveness of our algorithm compared to state-of-the-art approaches in particular when the images are corrupted with different types of noise.

63 citations

Journal ArticleDOI
TL;DR: A VLSI chip, called PYR, is developed to perform the standard filter and resampling operations required in pyramid and inverse pyramid transforms for these applications.
Abstract: Advanced techniques in image processing and computer vision increasingly require that image data be represented at multiple resolutions and at multiple sample rates. Application areas for such pyramid image representations include image compression, image enhancement, motion analysis, and object recognition. We have developed a VLSI chip, called PYR, to perform the standard filter and resampling operations required in pyramid and inverse pyramid transforms for these applications. The PYR chip processes image samples sequentially, in raster scan format, so is suited for pipeline architectures. The user can choose from a set of standard filters, through software control, to construct Gaussian, Laplacian, Subband, and related pyramid structures. A unique feature of the design is that it includes timing signals that are passed with the image data. These signals coordinate successive processing steps in a pipeline system as image sizes and sample rates change. The chip also includes circuits for edge extension and image addition, and it can be run in “spread tap” mode to provide twice the standard sample density. The PYR chip is implemented in standard cell technology. At a clock rate of 15 MHz, a single chip can simultaneously construct a Gaussian and a Laplacian pyramid from a 512 by 480 image in 22.7 msec (44 frame/second).

63 citations

Journal ArticleDOI
TL;DR: A novel pixel fusion rule based on multiresolution decomposition of the source images using wavelet, wavelet-packet, and contourlet transform is proposed that increases the quality of the fused image significantly, both visually and quantitatively, by preserving all the relevant information.
Abstract: Image fusion has been receiving increasing attention in the research community with the aim of investigating general formal solutions to a wide spectrum of applications. The objective of this work is to formulate a method that can efficiently fuse multifocus as well as multispectral images for context enhancement and thus can be used by different applications. We propose a novel pixel fusion rule based on multiresolution decomposition of the source images using wavelet, wavelet-packet, and contourlet transform. To compute fused pixel value, we take weighted average of the source pixels, where the weight to be given to the pixel is adaptively decided based on the significance of the pixel, which in turn is decided by the corresponding children pixels in the finer resolution bands. The fusion performance has been extensively tested on different types of images viz. multifocus images, medical images (CT and MRI), as well as IR − visible surveillance images. Several pairs of images were fused to compare the results quantitatively as well as qualitatively with various recently published methods. The analysis shows that for all the image types into consideration, the proposed method increases the quality of the fused image significantly, both visually and quantitatively, by preserving all the relevant information. The major achievement is average 50% reduction in artifacts.

62 citations

Journal ArticleDOI
Haohao Song1, Songyu Yu1, Xiaokang Yang1, Li Song1, Chen Wang1 
TL;DR: The proposed contourlet-based image adaptive water marking (CIAW) scheme is particularly superior to the conventional watermarking schemes when the watermarked image is attacked by some image processing methods, which destroy the HF subbands, thanks to theWatermarking components preserved in the LF subbands.
Abstract: In the contourlet transform (CT), the Laplacian pyramid (LP) decomposes an image into a low-frequency (LF) subband and a high-frequency (HF) subband. The LF subband is created by filtering the original image with 2-D low-pass filter. However, the HF subband is created by subtracting the synthesized LF subband from the original image but not by 2-D high-pass filtering the original image. In this paper, we propose a contourlet-based image adaptive watermarking (CIAW) scheme, in which the watermark is embedded into the contourlet coefficients of the largest detail subbands of the image. The transform structure of the LP makes the embedded watermark spread out into all subbands likely in which the LF subbands are included when we reconstruct the watermarked image based on the watermarked contourlet coefficients. Since both the LF subbands and the HF subbands contain watermarking components, our watermarking scheme is expected to be robust against both the LF image processing and the HF image processing attacks. The corresponding watermarking detection algorithm is proposed to decide whether the watermark is present or not by exploiting the unique transform structure of LP. With the new proposed concept of spread watermark, the watermark is detected by computing the correlation between the spread watermark and the watermarked image in all contourlet subbands fully. The proposed CIAW scheme is particularly superior to the conventional watermarking schemes when the watermarked image is attacked by some image processing methods, which destroy the HF subbands, thanks to the watermarking components preserved in the LF subbands. Experimental results show the validity of CIAW in terms of both the watermarking invisibility and the watermarking robustness. In addition, the comparison experiments prove the high-efficiency of CIAW again.

62 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202336
202299
202175
2020109
2019155
2018164