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An Hybrid Approach of Lossless Compression for Color Images
N. Subhash Chandra,M. Balraju,S. Mahaboob Basha,A. Govardhan
Asian Journal of Information Technology , 2012,
Abstract: With the increasing use of multimedia techniques, image compression requires higher performance as well as new features and also with the expansion of the telemedicine through the internet, the necessity of transmission of a great volume of images through medias of low speed, making impracticable to some applications, like cooperative diagnosis. A solution can be the use of hybrid techniques of compression as proposed in this study. This study deals with BDH technique, which is used to the compression of color images. In BDH technique, Huffman coding and Difference coding with Binary Plane Technique are combined. The BDH technique is compared with Binary Plane Technique (where no difference coding is used) and JPEG. Experimental results show that BDH improves compression rate compared to Binary Plane Technique.
A Novel Approach for Compression of Images Captured using Bayer Color Filter Arrays  [PDF]
Sang-Yong Lee,Antonio Ortega
Computer Science , 2009,
Abstract: We propose a new approach for image compression in digital cameras, where the goal is to achieve better quality at a given rate by using the characteristics of a Bayer color filter array. Most digital cameras produce color images by using a single CCD plate, so that each pixel in an image has only one color component and therefore an interpolation method is needed to produce a full color image. After the image processing stage, in order to reduce the memory requirements of the camera, a lossless or lossy compression stage often follows. But in this scheme, before decreasing redundancy through compression, redundancy is increased in an interpolation stage. In order to avoid increasing the redundancy before compression, we propose algorithms for image compression in which the order of the compression and interpolation stages is reversed. We introduce image transform algorithms, since non interpolated images cannot be directly compressed with general image coders. The simulation results show that our algorithm outperforms conventional methods with various color interpolation methods in a wide range of compression ratios. Our proposed algorithm provides not only better quality but also lower encoding complexity because the amount of luminance data used is only half of that in conventional methods.
Compression of Medical Images Using Wavelet Transforms  [PDF]
Ruchika,Mooninder Singh,Anant Raj Singh
International Journal of Soft Computing & Engineering , 2012,
Abstract: Medical image compression is necessary for huge database storage in Medical Centres and medical data transfer for the purpose of diagnosis. Wavelet transforms present one such approach for the purpose of compression. The same has been explored in paper with respect to wide variety of medical images. In this approach, the redundancy of the medical image and DWT coefficients are reduced through thresholding and further through Huffman encoding. This paper presents a lossy image compression technique which works well over most of the medical images.
Segmentation Based Multilevel Wide Band Compression for SAR Images Using Coiflet Wavelet  [PDF]
International Journal of Image Processing , 2011,
Abstract: Synthetic aperture radar (SAR) data represents a significant resource of information for a largevariety of researchers. Thus, there is a strong interest in developing data encoding and decodingalgorithms which can obtain higher compression ratios while keeping image quality to anacceptable level. In this work, results of different wavelet-based image compression andsegmentation based wavelet image compression are assessed through controlled experimentson synthetic SAR images. The effects of dissimilar wavelet functions, number of decompositionsare examined in order to find optimal family for SAR images. The choice of optimal wavelets insegmentation based wavelet image compression is coiflet for low frequency and high frequencycomponent. The results presented here is a good reference for SAR application developers tochoose the wavelet families and also it concludes that wavelets transform is rapid, robust andreliable tool for SAR image compression. Numerical results confirm the potency of this approach
A Comparison between Digital Image Watermarking in Tow Different Color Spaces Using DWT2  [PDF]
Mehdi Khalili
Computer Science , 2012,
Abstract: A novel digital watermarking for ownership verification and image authentication applications using discrete wavelet transform (DWT) is proposed in this paper. Most previous proposed watermarking algorithms embed sequences of random numbers as watermarks. Here binary images are taken as watermark for embedding. In the proposed approach, the host image is converted into the YCbCr color space and then its Y channel decomposed into wavelet coefficients. The selected approximation coefficients are quantized and then their four least significant bits of the quantized coefficients are replaced by the watermark using LSB insertion technique. At last, the watermarked image is synthesized from the changed and unchanged DWT coefficients. The experiments show that the proposed approach provides extra imperceptibility and robustness against wavelet compression compared to the traditional embedding methods in RGB color space. Moreover, the proposed approach has no need of the original image to extract watermarks.
Compression of Medical Images by Prediction on Wavelet Transform Coefficients
P.S. Arya Devi
Bonfring International Journal of Advances in Image Processing , 2012, DOI: 10.9756/bijaip.3085
Abstract: Compression of medical image is a challenging task as the compression has to be achieved without losing diagnostic quality of the images. Reducing the size of image finds its application in saving storage space and increasing transmission speed, as in case of teleradiology. On the decomposed details of an image, prediction is done. The high SNR (Signal to Noise ratio) and localization provided by wavelet coefficients makes it suitable for images. With few prediction coefficients, as small as 15, the whole image is reconstructed. The four variants of the method are studied to find its suitability for different types of images. The method is evaluated using various objective fidelity criteria.
Selection of Mother Wavelet For Image Compression on Basis of Nature of Image  [cached]
Gajanan K. Kharate,Varsha H. Patil,Niranjan L. Bhale
Journal of Multimedia , 2007, DOI: 10.4304/jmm.2.6.44-51
Abstract: Recently discrete wavelet transform and wavelet packet has emerged as popular techniques for image compression. The wavelet transform is one of the major processing components of image compression. The results of the compression change as per the basis and tap of the wavelet used. This paper compares compression performance of Daubechies, Biorthogonal, Coiflets and other wavelets along with results for different frequency images. Based on the result, it is proposed that proper selection of mother wavelet on the basis of nature of images, improve the quality as well as compression ratio remarkably. The prime objective is to select the proper mother wavelet during the transform phase to compress the color image. This paper includes the discussion on principles of image compression, image compression methodology, the basics of wavelet and orthogonal wavelet transforms, the selection of discrete wavelet transform with results and conclusion.
Haar Wavelet Based Approach for Image Compression and Quality Assessment of Compressed Image  [PDF]
Kamrul Hasan Talukder,Koichi Harada
Computer Science , 2010,
Abstract: With the increasing growth of technology and the entrance into the digital age, we have to handle a vast amount of information every time which often presents difficulties. So, the digital information must be stored and retrieved in an efficient and effective manner, in order for it to be put to practical use. Wavelets provide a mathematical way of encoding information in such a way that it is layered according to level of detail. This layering facilitates approximations at various intermediate stages. These approximations can be stored using a lot less space than the original data. Here a low complex 2D image compression method using wavelets as the basis functions and the approach to measure the quality of the compressed image are presented. The particular wavelet chosen and used here is the simplest wavelet form namely the Haar Wavelet. The 2D discret wavelet transform (DWT) has been applied and the detail matrices from the information matrix of the image have been estimated. The reconstructed image is synthesized using the estimated detail matrices and information matrix provided by the Wavelet transform. The quality of the compressed images has been evaluated using some factors like Compression Ratio (CR), Peak Signal to Noise Ratio (PSNR), Mean Opinion Score (MOS), Picture Quality Scale (PQS) etc.
Compression of MR Images Using DWT by Comparing RGB and YCbCr Color Spaces  [PDF]
Agrawal Jayprkash, Ritu Vijay
Journal of Signal and Information Processing (JSIP) , 2013, DOI: 10.4236/jsip.2013.44046
Abstract: This paper consists of a lossy image compression algorithm dedicated to the medical images doing comparison of RGB and YCbCr color space. Several lossy/lossless transform coding techniques are used for medical image compression. Discrete Wavelet Transform (DWT) is one such widely used technique. After a preprocessing step (remove the mean and RGB to YCbCr transformation), the DWT is applied and followed by the bisection method including thresholding, the quantization, dequantization, the Inverse Discrete Wavelet Transform (IDWT), YCbCr to RGB transform of mean recovering. To obtain the best compression ratio (CR), the next step encoding algorithm is used for compressing the input medical image into three matrices and forward to DWT block a corresponding containing the maximum possible of run of zeros at its end. The last step decoding algorithm is used to decompress the image using IDWT that is applied to get three matrices of medical image.
Protecting Copyrights of Color Images using a Watermarking Scheme Based on Secret Sharing and Wavelet Transform  [cached]
Shang-Lin Hsieh,I-Ju Tsai,Bin-Yuan Huang,Jh-Jie Jian
Journal of Multimedia , 2008, DOI: 10.4304/jmm.3.4.42-49
Abstract: This paper presents a novel digital watermarking scheme for copyright protection against piracy of color images. Unlike traditional watermarking schemes that directly embed watermarks into host images, the scheme encodes the watermark prior to watermark embedding to improve tolerance to attacks. The process utilizes the secret sharing scheme with the feature extracted form the host image by the discrete wavelet transform. Moreover, different from other watermarking schemes that require manual adjustment in the embedding scaling factors to embed the watermark, the scheme can automatically calculate the scaling factor for different images while still preserving robustness and imperceptibility. The experimental results show that the scheme can resist several attacks including cropping, scaling, and JPEG compression. Furthermore, the ability of extracting unique features from different images, which is an important requirement for feature extraction, is also demonstrated in the experiment.
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