Theses and Dissertations

Permanent URI for this collectionhttp://ir.daiict.ac.in/handle/123456789/1

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Subject: search.filters.subject.Digital Image

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    Medical image security with cheater identification using secret sharing scheme
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Krishnan, Arun; Das, Manik Lal
    The progress in the field of information and communication technology has brought about quick and efficient transfer of textual as well as multimedia data . However, the growth of technology has also provided new ways for unauthorized access and illegal modifications of data, thereby, affecting data security. Secure data transmission is a necessity, especially in medical and legal fields. Doctors need to be convinced about the legitimacy of the medical images as well as associated health records they receive, especially in networking applications such as telediagnosis, teleconsultation,telesurgery etc. Furthermore, medical images should not be discernible to malignant agents with evil intentions on patient’s health. This thesis proposes a (k,n) secret sharing scheme for secure transfer of medical images and related electronic patient records (EPR) to a team of doctors through public insecure channels. The scheme prevents unauthorized access and detects illegal tampering of transmitted images and records. The scheme also considers the presence of a deceiver among the group of participants and includes techniques to detect any deception from the participant doctors and uniquely identify the deceiver. Furthermore, the scheme includes procedures to prevent the unauthorized release of medical image by any of the participating doctors. Simulation results shows that the proposed scheme satisfies all the security features discussed above.
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    ItemOpen Access
    Learning based approach for image compression
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Kumar, Dheeraj; Joshi, Manjunath V.
    Data compression is a process of storing same information with less data or space in computer memory. There are many image compression techniques that are available for storing images with less storage space. Minimizing storage space minimizes the bandwidth required for transmission. In the proposed algorithm first level Discrete Wavelet Transformation (DWT, with Daubechies wavelets db4 as a mother wavelet) is applied on original image after which only low resolution coefficients are retained. Further Embedded Zero Tree Wavelet based algorithm (EZW) [10] is applied for best image quality at the given bit rate. We are using a set of images as database. For every input image Content Based Image Retrieval (CBIR) [7] technique is applied on database which results in some images, having similar content. At the receiver a learning based approach is used to decompress from resulted database images. Structure Similarity Index Measurement (SSIM) [15] an image quality assessment is used for similarity check. Inverse DWT is applied to get the estimate of the original. This is a lossy compression and results are compared with JPEG [13] and JPEG2000 [8] compression.
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    ItemOpen Access
    Detection of tampering in digital images using feature based hash generation
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2014) Mall, Vinod Kumar; Roy, Anil Kumar; Mitra, Suman Kumar
    Recent years have witnessed an exponential growth in the use of digital images due to development of high quality digital cameras and multimedia technology. Easy availability of user-friendly image editing software has made modification of images a popular child’s play. In this environment, the integrity of an image cannot be taken for granted. Malicious tampering has serious ramification in legal documents, copyright issues, photojournalism, celebrities’ lifestyles, fashion statements, beauty and fitness products, entertainment sector, medical science, biometric images and forensic cases. The proposed work is based on features based hash generation of a digital image and thereby detection and localization of image tampering that is done with malicious intention, no matter howsoever small the tampering is. The hashing algorithm generates a short binary string by extracting the feature vectors of the image and mapping them into robust hash values. This hash mapping meets the two requirements of being sensitive to tampering in the image and being robust against content preserving manipulations. The first part of the work uses correlation coefficient to generate a hash representation of the image which is then utilized for tampering detection. This method is extended later to use properties of Singular Value Decomposition (SVD) to derive the hash values. SVD enables us to generate key based hash values. We show that this hash can be used in secured transmission of image information on the public network. We emphasize that the malicious tampering is generally done on the structural part of the image. Therefore, in the third part of our study, we have used Canny Edge Detector to extract the features of the image by detecting the edges present in it. Having the edges identified, tampering detection and localization are carried out. This method of tampering detection and localization has been found to be promising. The last part of the thesis discusses Comprehensive Image Index which is able to detect multiple types of tampering, viz., brightness, contrast, and structural, simultaneously. We observe that a structural tampering is always followed by brightness and contrast changes in the image. We also establish that even brightness or contrast or both change can be seen as a malicious tampering if exceeds a threshold value. The sensitivity of the technique and its robustness have been discussed quantitatively for each method.