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khemraj Offline
#1 Posted : Saturday, December 28, 2013 8:37:27 AM(UTC)

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Super-Resolution-based Inpainting

For More Information you may contact On.
Technosoft Systems / Creative Logic .
Email: creative.logic.softwares@gmail.com

                  A coarse version of the input image is first in painted by a non- parametric patch sampling. Compared to existing approaches, some improvements have been done. The in painted of a coarse version of the input image allows to reduce the computational complexity, to be less sensitive to noise and to work with the dominant orientations of image structures. From the low-resolution in painted image, a single-image super-resolution is applied to recover the details of missing areas. Experimental results on natural images and texture synthesis demonstrate the effectiveness of the proposed method.
Existing methods can be classified into two main categories. The first category concerns diffusion-based approaches which propagate linear structures or level lines via diffusion based on partial differential equations and variation methods. Unfortunately, the diffusion-based methods tend to introduce some blur when the hole to be filled-in is large. The second family of approaches concerns exemplar-based methods which sample and copy best matches texture patches from the known image neighborhood. These methods have been inspired from texture synthesis techniques and are known to work well in cases of regular or repeatable textures. The first attempt to use exemplar-based techniques for object removal has been reported in. Authors in improve the search for similar patches by introducing an a priori rough estimate of the in painted values using a multi-scale approach which then results in an iterative approximation of the missing regions from coarse to fine levels.
                 In proposed system two main components are the in-painting and the super-resolution algorithms. More specifically, the following steps are performed:
1. A low-resolution image is first built from the original picture;
2. An in-painting algorithm is applied to fill-in the holes of the low-resolution picture;
3. The quality of the in-painted regions is improved by using a single-image SR method.

Image in painting
        In painting is the process of reconstructing lost or deteriorated parts of images and videos. For instance, in the museum world, in the case of a valuable painting, this task would be carried out by a skilled art conservator or art restorer. In the digital world, in painting refers to the application of sophisticated algorithms to replace lost or corrupted parts of the image data.

Image restoration

Image restoration is the operation of taking a corrupted/noisy image and estimating the clean original image. Corruption may come in many forms such as motion blur, noise, and camera miss focus.
            Super resolution (SR) is a class of techniques that enhance the resolution of an imaging system. In some SR techniques—termed optical SR—the diffraction limit of systems is transcended, while in others—geometrical SR—the resolution of digital imaging sensors is enhanced.
Super-resolution algorithm
Once the in painting of the low-resolution picture is completed, a single-image super-resolution approach is used to reconstruct the high resolution of the image. The idea is to use the low-resolution in painted areas in order to guide the texture synthesis at the higher resolution. The problem is to find a patch of higher-resolution from a database of examples.
1. Dictionary building: it consists of the correspondences between low and high resolution image patches. The unique constraint is that the high-resolution patches have to be valid, i.e. entirely composed of known pixels. In the pro- posed approach, high-resolution and valid patches are evenly extracted from the known part of the image. The size of the dictionary is a user-parameter which might influence the overall speed/quality trade-off. An array is used to store the spatial coordinates of HR patches (DHR). Those of LR patches are simply deduced by using the decimation factor;
2. Filling order of the HR picture: the computation of the filling order is similar to the one described in Section 3. It is computed on the HR picture with the sparsity-based method. The filling process starts with the patch  HRp 10 Olivier Le Meur and Christine Guillemot having the highest priority. This improves the quality of the in painted picture compared to a raster-scan filling order;
3. For the LR patch corresponding to the HR patch having the highest priority, its K-NN in the in painted images of lower resolution are sought. The number of neighbors is computed as described in the previous section. The similarity metric is also the same as previous;
4. Weights wp, pj are calculated by using a non-local means method as if we would like to perform a linear combination of these neighbors. However, the similarity distance used to compute the weights is composed of two terms: the first one is classical since this is the distance between the current LR patch and its LR neighbors, noted d( LRp ,  LRp,pj ). The second term is the distance between the known parts of the HR patch  HRp and the HR patches corresponding to the LR neighbours of  LRp . Say differently, the similarity distance is the distance between two vectors composed of both pixels of LR and HR patches. The use of pixel values of HR patches allows to constraint the nearest neighbour search of LR patches.
5. A HR candidate is finally deduced by using a linear combination of HRpatches with the weights previously computed:
 HRp =Xpj2DHRwp,pj ×  p,pj (4)
with the usual conditions 0 ≤ wp,pj ≤ 1, andPk wp,pk = 1.
6. Stitching: the HR patch is then pasted into the missing areas. However, as an overlap with the already synthesized areas is possible, a seam cutting
the overlapped regions is determined to further enhance the patch blending. The minimum error boundary cut [21] is used to find a seam for which the two patches match best. The similarity measure is the Euclidean distance between all pixel values in the overlapping region. More complex metrics have been tested but they do not substantially improve the final quality. At most four overlapping cases (Left, Right, Top and Bottom) can be encountered. There are sequentially treated in the aforementioned order. The stitching algorithm is only used when all pixel values in the overlapping region are known or already synthesized. Otherwise, the stitching is disabled. After the filling of the current patch, priority value is recomputed and the afore-mentioned steps are iterated while there exist unknown areas.
System Configuration:-
H/W System Configuration:-
        Processor               -    Pentium –III
Speed                                -    1.1 Ghz
RAM                                 -    256  MB(min)
Hard Disk                          -   20 GB
Floppy Drive                     -    1.44 MB
Key Board                         -    Standard Windows Keyboard
Mouse                                -    Two or Three Button Mouse
Monitor                              -    SVGA


S/W System Configuration:-
Operating System            :Windows XP
Front End                          :   JAVA,RMI, SWING
            We have introduced a novel algorithm for image in-painting that attempts to replicate the basic techniques used by professional restorators. The basic idea is to smoothly propagate information from the surrounding areas in the isophotes direction. The user needs only to provide the region to be in-painted, the rest is automatically performed by the algorithm in a few minutes. The in-painted images are sharp and without color artifacts. The examples shown suggest a wide range of applications like restoration of old photographs and damaged film, removal of superimposed text, and removal of objects. The results can either be adopted as a final restoration or be used to provide an initial point for manual restoration, thereby reducing the total restoration time by orders of magnitude.

Edited by user Wednesday, July 16, 2014 12:43:32 AM(UTC)  | Reason: Not specified

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