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Extract from original Lena ͑ a ͒ and images for 4 ϫ reconstructions: bilinear interpolation ͑ b ͒ , WZP ͑ c ͒ , and directional CS ͑ d ͒ .
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Cycle spinning, a technique mainly used for wavelet denoising, has also been shown to be successful toward image resolution upscaling in the wavelet domain. We propose a directional variant of the cycle spinning methodology. We obtain estimates of local edge orientation from a wavelet decomposition of the available low-resolution image and use this...
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Citations
... The Discrete Wavelet Transform (DWT) of an image which consists of four distinct parts which include an array of approximation coefficients and three arrays of detailed coefficients. The three detailed coefficients HL, LH and HH give the vertical, horizontal and diagonal details such as edges, singularities and orientation, respectively [8]. A. Temizel and Theodore Vlachos [23] used Wavelet Zero Padding (WZP) for the generation of a first approximation of the enhanced image followed by cyclic spinning to achieve the final upscaled enhanced image. In this method, vertical and horizontal activities are measured through HL and LH, but the diagonal CS involves extra computational complexities. ...
... Fig. 2 shows the scheme for the super-resolution. ) and an approximation f in (i, j) is given as Fig. 4 a Satellite image resolution enhanced by [23] b Image Resolution enhanced by [5] c Image Resolution enhanced by [6], d Image Resolution Enhanced by proposed technique Lower values the mean square error shows good reconstruction result and high PSNR shows good result. ...
... N} the universal quality index is given by Eq. (14). Fig. 5 a Baboon image resolution enhanced by [23] b Image Resolution enhanced by [5] c Image Resolution enhanced by [6], d Image Resolution Enhanced by proposed technique (a) (b) (c) (d) Fig. 6 a Lena image resolution enhanced by [23] b Image Resolution enhanced by [5] c Image Resolution enhanced by [6], d Image Resolution Enhanced by proposed technique ...
This paper presents an image of Super-Resolution (SR) technique by the construction of DT-CWT coefficients for a larger scale from the information at a smaller scale for all the subbands. The DT-CWT coefficients prediction for each subband of an image at a finer level is based on phase prediction and estimation of the magnitude separately, followed by combining the magnitude and phase. Inverse DT-CWT is taken with the coefficients at a finer level of each subband along with a Low-Resolution (LR) image in place of a low subband to reconstruct a high-resolution image. The proposed technique is applied to various images, including satellite and standard images. The quantitative and visual results have established the superiority of the proposed scheme over conventional and various state-of-the-art techniques.
... bi-histogram equalization (BBHE) and dualistic sub image histogram equalization (DSIHE), exposure-based sub image histogram equalization (ESIHE), non-parametric modified histogram equalisation (NMHE), singular value decomposition (SVD), standard intensity deviation clipped sub image histogram equalization (SIDCSIHE), and contrast enhancement by scaling reconstruction approximation coefficient using SVD (CE_SRA_SVD)) [9][10][11][12][13][14]. The proposed method outperform over conventional and state-of-art technique of resolution enhancement technique (i.e. the nearest neighbour, bilinear, bi-cubic, wavelet zero padding (WZP), Regularity-preserving image interpolation, new edge-directed interpolation (NEDI), hidden Markov model (HMM), HMM-based image super-resolution (HMM SR), WZP and cycle-spinning (WZP-CS), DWT based super-resolution (DWT SR), complex wavelet transform based super-resolution (CWT SR), and modified context-based image interpolation (MCBII)) [15][16][17][18][19][20][21][22]. The paper is structured as follows, section 2 contains the proposed method and section 3 we discuss experimental results. ...
Image enhancement techniques are prominently used to analyze the image by enhancing key factors like contrast, resolution, and quality of the image. With the proper analysis of images, it is desirable to pre-process the image for resolution and contrast enhancement. We present here a new approach based on discrete wavelet transform (DWT), singular value decomposition (SVD) for image contrast and resolution enhancement, The contrast of the image is enhanced by maximum value fusion technique applied to the images created by using modified cuckoo search algorithm (CSA) and singular value decomposition separately. The masking approach is employed, for obtaining residual pixel value between original and scaled images independently. The resolution of the image is enhanced by combining interpolated high-frequency sub-band and maximum value fusion images. The proposed algorithm helps to minimize the noise artifacts and over enhancement problems. Experimental results are tested in terms of peak signal to noise ratio (PSNR) and absolute mean brightness error (AMBE). The proposed method shows better performance compared to other contrast and resolution enhancement techniques.
... However, in terms of performance, the directional cycle spinning is far better than the conventional cycle spinning. [20,21]. Gaussian mixture (GM), a statistical approach, was used to compute the correlation between the low wavelet and high wavelet coefficient. ...
The super-resolution (SR) technique reconstructs a high-resolution image from single or multiple low-resolution images. SR has gained much attention over the past decade, as it has significant applications in our daily life. This paper provides a new technique of a single image super-resolution on true colored images. The key idea is to obtain the super-resolved image from observed low-resolution images. A proposed technique is based on both the wavelet and spatial domain-based algorithms by exploiting the advantages of both of the algorithms. A back projection with an iterative method is implemented to minimize the reconstruction error and for noise removal wavelet-based de-noising method is used. Previously, this technique has been followed for the grayscale images. In this proposed algorithm, the colored images are taken into account for super-resolution. The results of the proposed method have been examined both subjectively by observation of the results visually and objectively by considering the peak signal-to-noise ratio (PSNR) and mean squared error (MSE), which gives significant results and visually better in quality from the bi-cubic interpolation technique.
... However, in terms of performance, the directional cycle spinning is far better than the conventional cycle spinning. [20,21]. Gaussian mixture (GM), a statistical approach, was used to compute the correlation between the low wavelet and high wavelet coefficient. ...
... In present decades, several wavelet based image resolution strategies are introduced with conventional techniques (interpolation) namely, DWT [2], SWT [3], DT-CWT [4], Wavelet Zero Padding and cycle-spinning [5], wavelet with directional cycle spinning [6] and DWT based super resolution [7]. ...
Satellite images place vital role in agriculture, Disaster mitigation and geosciences applications. Satellite images include both spatial and temporal resolution, in that spatial resolution is influence the accuracy of ground objects. The main idea of this work is to enhance the resolution of satellite images. In this work, a dual domain filtering based approach is introduced for resolution enhancement (RE). Initially, the source image is subdivided into approximation and detail coefficients by Stationary Wavelet transform (SWT). The detail coefficients are interpolated based on bi-linear interpolation. The interpolated detail coefficients are applied to Non-Local Means (NLM) filter to minimize the artifacts produced by SWT. The filtered detail and approximation coefficients of source image are fed to ISWT to attain high resolution (HR) image. The proposed system is superior to other existing strategies like DWT-NLM and DWT-SWT.
... SR algorithms cost is less compared to other sensors used to increase the resolution of images [1], [2]. Recently many SR algorithms have been proposed [3]. The wavelet based sparse mixing plays very important role in image enhancement of satellite images. ...
... However, ringing artifacts not only occur in the neighborhood of edges; in particular, they are predominantly correlated with the orientation of the edges. A directional CS technique, which can refine better edge orientation and prevent ringing artifacts, was introduced in Ref. 22. Additionally, it can reduce the computational complexity compared with a nondirectional CS technique. ...
This paper proposes a new image resolution enhancement approach based on discrete wavelet transform (DWT) and new edge-directed interpolation (NEDI) for degraded satellite images by geometric distortion to correct the errors in image geometry and recover the edge details of directional high-frequency sub-bands. The observed image is decomposed into four frequency sub-bands through DWT, and then the three high-frequency sub-bands and the observed image are applied with NEDI. In order to better preserve the edges and remove potential noise in the estimated high-frequency sub-bands, an adaptive threshold is applied to process the estimated wavelet coefficients. Finally, the enhanced image is reconstructed by applying inverse DWT. Four new criteria are introduced aiming to better assess the overall performance of the proposed approach for different types of satellite images. A public satellite images data set is selected for the validation purpose. The visual and quantitative results show the superiority of the proposed approach over the conventional and state-of-the-art image resolution enhancement techniques.
... Inverse filtering or generalized inverse filtering is used to recover the blurred image, but is highly sensitive to additive noise. The Wiener filtering assures noise smoothing and inverse filtering [14,15,16]. It simultaneously inverts the blurring and eliminates the additive noise [10,11,13]. ...
... To reduce this shortcoming, a refined HMT based method was proposed in [19], where the magnitude parameters are estimated using the HMT model, and the sign parameters are estimated based on a higher correlation among the parameters between a high-pass filtered version of the LR image and the high-frequency subbands. A Directional Cycle-Spinning (DCS) method was introduced in [20], where approximates of edge orientation information are derived from a wavelet decomposition of the LR image and used to affect the choice of CS parameters. It can refine better edge orientation and prevent staircase artefacts. ...
The existing wavelet-based image resolution enhancement techniques have many assumptions, such as limitation of the way to generate low-resolution images and the selection of wavelet functions, which limits their applications in different fields. This paper initially identifies the factors that effectively affect the performance of these techniques and quantitatively evaluates the impact of the existing assumptions. An approach called Optimal Factor Analysis employing the genetic algorithm is then introduced to increase the applicability and fidelity of the existing methods. Moreover, a new Figure of Merit is proposed to assist the selection of parameters and better measure the overall performance. Abstract-The existing wavelet-based image resolution enhancement techniques have many assumptions, such as limitation of the way to generate low-resolution images and the selection of wavelet functions, which limits their applications in different fields. This paper initially identifies the factors that effectively affect the performance of these techniques and quantitatively evaluates the impact of the existing assumptions. An approach called Optimal Factor Analysis employing the genetic algorithm is then introduced to increase the applicability and fidelity of the existing methods. Moreover, a new Figure of Merit is proposed to assist the selection of parameters and better measure the overall performance. The experimental results show that the proposed approach the performance of the selected image resolution enhancement methods and has potential to be extended to other methods.
... • WZP, CS, and edge rectification (WZP-CS-ER) [12]; ...
