Faculty Publications
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Publications by NITK Faculty
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Item Single depth image super-resolution via high-frequency subbands enhancement and bilateral filtering(Institute of Electrical and Electronics Engineers Inc., 2016) Balure, C.S.; Ramesh Kini, M.; Bhavsar, A.This paper addresses the problem of super-resolution (SR) from a single low-resolution (LR) depth image to a high-resolution (HR) depth image. A simple yet effective method has been proposed using Discrete Wavelet Transform (DWT), Stationary Wavelet Transform (SWT), and by utilizing the gradient information of the interpolated LR image. We propose an intermediate stage to enhance the high-frequency subbands to recover the HR image for both noiseless and noisy scenarios. The proposed method has been validated on Middlebury dataset for different upsampling factors (i.e. 2, 4, 8) and is shown to be superior when compared with some related DWT and SWT based SR methods. We also demonstrate encouraging performance of the approach on noisy depth images. © 2016 IEEE.Item Depth image super-resolution: A review and wavelet perspective(Springer Verlag service@springer.de, 2017) Balure, C.S.; Ramesh Kini, M.We propose an algorithm which utilizes the Discrete Wavelet Transform (DWT) to super-resolve the low-resolution (LR) depth image to a high-resolution (HR) depth image. Commercially available depth cameras capture depth images at a very low-resolution as compared to that of the optical cameras. Having an highresolution depth camera is expensive because of the manufacturing cost of the depth sensor element. In many applications like robot navigation, human-machine interaction (HMI), surveillance, 3D viewing, etc. where depth images are used, the LR images from the depth cameras will restrict these applications, thus there is a need of a method to produce HR depth images from the available LR depth images. This paper addresses this issue using DWT method. This paper also contributes to the compilation of the existing methods for depth image super-resolution with their advantages and disadvantages, along with a proposed method to super-resolve depth image using DWT. Haar basis for DWT has been used as it has an intrinsic relationship with super-resolution (SR) for retaining the edges. The proposed method has been tested on Middlebury and Tsukuba dataset and compared with the conventional interpolation methods using peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) performance metrics. © Springer Science+Business Media Singapore 2017.Item Guidance-based improved depth upsampling with better initial estimate(Inderscience Publishers, 2021) Balure, C.S.; Ramesh Kini, M.Like optical images, depth images are also gaining popularity because of its use in many applications like robot navigation, augmented reality, 3DTV and more. The commercially available depth cameras generate depth images which suffer from low spatial resolution, corrupted with noise, and missing regions. Such images need to be super-resolved, denoised and inpainted before using them to have better accuracy. Super-resolution (SR) techniques can be used to produce a high-resolution output. Since SR is an ill-posed inverse problem, a good initial estimate is always a good regulariser to find the optimal solution. We propose an initial estimate as part of our SR pipeline, esp. ×8, which will helps in quick convergence and accurate output. We propose a cascade approach by combining residual interpolation (RI) method with anisotropic total generalised variation (ATGV) method, both uses HR guidance image. The improvements are shown qualitative and quantitative with different levels of noise. © 2021 Inderscience Publishers. All rights reserved.