Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 5 Articles
This paper proposes a new wavelet domain denoising algorithm. In the results of conventional wavelet domain\r\ndenoising methods, ringing artifacts or wavelet-shaped noises are sometimes observed due to thresholding of small\r\nbut important coefficients or due to generation of large coefficients in flat areas. In this paper, nonlocal means filtering\r\nis applied to each subband of wavelet decomposition, which can keep small coefficients and does not generate\r\nunwanted large coefficients. Since the performance of nonlocal means filtering depends on the appropriate kernel\r\nbandwidth, we also propose a method to find global and local kernel bandwidth for each subband. In comparison\r\nwith conventional methods, the proposed method shows lower PSNR than BM3D when pseudo white Gaussian noise\r\nis added, but higher PSNR than the spatial nonlocal means filtering and wavelet thresholding methods. For the\r\nmixture noise or Poisson noise, which may better explain the real noise from camera sensors, the proposed method\r\nshows better or comparable results than the state-of-the-art methods. Also, it is believed that the proposed method\r\nshows better subjective quality for the noisy images captured in the low-illumination conditions....
This paper presents a new human recognition method based on features extracted from retinal images. The\r\nproposed method is composed of some steps including feature extraction, phase correlation technique, and feature\r\nmatching for recognition. In the proposed method, Harris corner detector is used for feature extraction. Then,\r\nphase correlation technique is applied to estimate the rotation angle of head or eye movement in front of a retina\r\nfundus camera. Finally, a new similarity function is used to compute the similarity between features of different\r\nretina images. Experimental results on a database, including 480 retinal images obtained from 40 subjects of DRIVE\r\ndataset and 40 subjects from STARE dataset, demonstrated an average true recognition accuracy rate equal to\r\n100% for the proposed method. The success rate and number of images used in the proposed method show the\r\neffectiveness of the proposed method in comparison to the counterpart methods....
In this paper, a robust and oblivious image watermarking algorithm using the discrete wavelet transform (DWT) is proposed for the security provision to the information protection. Results show that this algorithm is robust to many image attacks. Various attacks were tested on a number of 8-bit grayscale cover images of size 256 × 256, embedded with binary watermark image of size 16 × 16. Visual quality of both watermarked image and extracted watermark is good. The performance of the proposed algorithm is calculated in terms of PSNR, NCC, BER and SM....
In this paper, we present a modified clustering algorithm to segment color images. The proposed technique is\r\nbased on the robust c-prototypes algorithm with some modifications in its objective function and updating\r\nequations. The JK chromatic subspace of the IJK color space is used to segment color images. The algorithm\r\nperformance is tested on real images with natural artifacts that make the segmentation process difficult.\r\nAdditionally, a remote sensing image is segmented to demonstrate that the proposed algorithm can be used in\r\nreal applications. Simulation results indicate that the proposed method is more effective than others proposed in\r\nthe literature in terms of objective and subjective criteria....
In this paper, we propose techniques to assess the objective quality for stereoscopic 3D video content, related to\r\nmotion and depth map features. An analysis has been carried out in order to understand what causes the\r\ngeneration of visual discomfort in the viewer''s eye when visualizing a 3D video. Motion is an important feature\r\naffecting 3D experience but is also often the cause of visual discomfort. Guidelines are obtained after applying the\r\nalgorithm to quantify the impact over viewer''s experience when common cases happen, such as high motion\r\nsequences, scene changes with abrupt parallax changes, or complete absence of stereoscopy....
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