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IEEE Transactions on image processing Vol. 20, No.10, October 2011 by Andrea Giachetti and Nicola Asuni Speaker : 吳惠仙 首頁須把論文出處,含發表期刊,發 表年與作者清楚標示出來.

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Presentation on theme: "IEEE Transactions on image processing Vol. 20, No.10, October 2011 by Andrea Giachetti and Nicola Asuni Speaker : 吳惠仙 首頁須把論文出處,含發表期刊,發 表年與作者清楚標示出來."— Presentation transcript:

1 IEEE Transactions on image processing Vol. 20, No.10, October 2011 by Andrea Giachetti and Nicola Asuni Speaker : 吳惠仙 首頁須把論文出處,含發表期刊,發 表年與作者清楚標示出來

2 Outline  Introduction What’s the problem about image upscaling?  Related Works Polynomial interpolation Statistical Methods Edge-directed interpolation  Proposed Scheme ICBI(Iterative Curvature Based Interpolation) CUDA  Experiment Results Objective test and Subjective test  Conclusions 論文報告大綱需有這幾個 項目

3 What’s the problem about image upscaling?  Sometimes we need to obtain a digital image to be represented on a large bitmap from original data, it should look like it had acquired with a sensor having the resolution of the upscaled image or at least, present a “natural” texture. Introduction 一開始先把論文要解決的問題說 清楚,盡可能用圖來解說

4 What’s the problem about image upscaling?  But we have a problem is, how to insert these unknown values to the high resolution image?  The solution to the problem is often referred to also as “single image super-resolution” that allows to obtain an High Resolution image from its Low Resolution counterpart. Introduction 緊接著請把這個題目的挑戰性做 個說明,盡可能用圖來解說

5 Polynomial interpolation  The simplest interpolation based on linear filtering.  Methods like: Nearest Neighbor interpolation, Bilinear, Bicubic…  adv. : computationally efficient(Bicubic is not.) dis. : blur and jagged contours Related works 在 Related Works 簡 要介紹解決此問題 的相關研究,把其 概念想法,優點與 缺點說清楚

6 Statistical Methods  Some authors have tried to exploit pixel or texture statistics or database of example images to obtain good high resolution images.  Methods like : Example-based learning single- image for super-resolution[2008]  adv. : variety of natural textures and scales makes. dis. : need a sufficiently representative set of examples. Related works 讓投影片有高可讀性, 盡可能用完整英文句子。 重點可以特別標示出來。

7 Edge-directed Interpolation  These methods try to improve the accuracy of the interpolation characterizing the edge features in a larger region. They aims at interpolating along edges rather than across them to prevent blurring.  Methods like: NEDI(New Edge-Directed Interpolation)[2001] iNEDI(improved NEDI)[2008]  adv. : have good results for natural images. dis.: NEDI and iNEDI have high computationally. Related works 介紹相關研究時,盡可能按 照其發表時間依序介紹

8 Edge-directed Interpolation  NEDI estimates local covariance coefficients from a low- resolution image Use these covariance estimates to adapt the interpolation at a higher resolution based on the geometric duality between the low-resolution covariance and the high-resolution covariance. Note:NEDI and iNEDI still create evident artifacts due to the effect of edge discontinuities. Related works vs. 藉由相關研究的探討,來點出所提演算法想 要真正解決的問題點

9 two-step hole filling from NEDI  in the first one, pixels indexed (Fig1.A) are computed as a weighted average of the four diagonal neighbors.  in the second the remaining holes(Fig1.B) are filled with the same rule(in horizontal and vertical directions). Proposed Scheme-ICBI 介紹所提演算 法時,應先描 述其主要想法, 盡可能用圖來 解說

10 FBCI(Fast Curvature-Based Interpolation )  average of the two neighbors in the direction of lowest second order derivative using 8 valued neighboring pixels, then assigning to the point(2i+1, 2j+1) in the direction where the derivative is lower. Proposed Scheme-ICBI

11 Energy Function  Define an energy component at each new pixel location that is locally minimized when the second order derivative are constant.  Then modified the interpolated pixel values in an iterative greedy procedure trying to minimize the global energy. Proposed Scheme-ICBI U(2i+1,2j+1) : final value Uc(2i+1,2j+1) : curvature smoothing Ue(2i+1,2j+1) : curvature enhancement Ui(2i+1,2j+1) : isophote smoothing a, b, c, T : chosen by trial and error in order to maximize the perceived and measured image quality. 數學式要簡單扼要,符號要定 義清楚,數學式的物理意義要 解說清楚

12 Energy Function Proposed Scheme-ICBI

13 Contributions  A review of constant covariance constraint used in the NEDI method with the proof of the relationship of that constraint with the second order derivatives smoothness used in our algorithm.  ICBI based on the iterative smoothing of second order derivatives. The algorithm is initialized using a simple filling rule based on second order derivatives(FCBI) that can be considered an edge directed interpolation algorithm too.  ICBI method demonstrated to be an improvement over previous ones, providing a reasonable reconstruction of the missing information and requiring considerably less computational power than other methods achieving good scores.  A GPU implementation of the ICBI method able to enlarge images at interactive frame rates... 實驗結果前可以先總結 一下論文的主要貢獻

14 Objective Test Experiment Results 可以把實驗結果中要注意的地方清 楚標示出來

15 Objective Test  Dell XPS M1210 laptop with Intel Core2 Duo T GHz CPU.  PSNR  Computation Times Experiment Results 把實驗條件與目的,評量結果 的量化指標等說明清楚

16 Subjective Test  There are12 people to compare images, in order to select the best average “perceived quality”. Experiment Results

17 CUDA implementation for real-time  GPUCard : nVidia GeForce GTX280  Language : Matlab and C  4x enlargement of 128x128 images in 16.2ms on average, corresponding to a ideal frame rate of 62 frames per second.  2x enlargement of 256x256 images in 12.3ms on average. Experiment Results 最好讓大家可以由所提演算法的主要想法,就能理 解推論實驗結果的正確必然性

18 Conclusion  ICBI based on a greedy minimization of an energy function defined at the interpolated pixel locations.  ICBI is not computationally expensive like example-based methods or NEDI and is easily parallelizable.  Noise image? Conclusion 最後為論文做個總結,簡述其所解決的問題與 主要貢獻。最好能提一下所提方法的限制與可 能的問題

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