7325

6831

كارشناسي ارشد

نرم افزار

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1391

دوازده، 144ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

شادرخ سماوي

6/9/91

محمدعلي منتظري، مسعود عمومي

1396/09/21

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID6831

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

145 Gray scale Image Watermarking using Hadamard Transform Elham Shabanali Fami e shabanali@ec iut ac ir Date of Submission Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Shadrokh Samavi Samavi96@cc iut ac irAbstract Nowadays digital contents are rapidly and inexpensively being distributed around the worldby using the internet This issue has become a source of great concern for multimedia contentproducers Copyright protection of digital contents in virtual environments requires a reliableapproach Watermarking technology was introduced to solve this problem and now it is widely inuse The process of hiding owner related information in digital contents was namedwatermarking Since images are the most abundant form of digital contents digital image swatermarking is the most common kind of watermarking In this routine the owner s informationmay be embedded in spatial or transform domain of host images Due to fidelity and strengthrequirements in noisy situations recent watermarking methods favor transform domainwatermarking There is a trade off between watermarking strength and fidelity The use of moreresistant watermarking jeopardizes the fidelity of the watermarked image Because of that presenting watermarking methods that satisfy these two features is one of the challenging issuesin watermarking technology In this thesis resistant and perspicuous watermarking methods arepresented for digital gray level images In these methods a binary logo that identifies content sowner will be concealed in Hadamard transform coefficients of host image blocks The firstproposed method employs a compression technique to embed watermark In this method watermark information is stored in regions with high texture and entropy Region selection isdone by use of the entropy measure of each image block The owner identifier is obtained byinformed watermark extraction In this process the host image is used for determiningwatermarked blocks and watermark coefficients In the second method the watermark logo isredundantly hidden in mid frequencies of Hadamard transform To do so a number of matrices arecreated from the same frequency coefficients of Hadamard transform Then these matrices aredecomposed into their bit planes The watermark logo is replaced with the plane that providesmore robustness and fidelity In this method watermark detection needs no information from thehost image and the watermark is blindly extracted Watermark extraction routine is based onvoting between different copies of watermark that were hidden in the host image While thesewatermarking methods are robust against compression crop and filtering attacks they alsopossess sufficient fidelity Keywords Bit plane Compression Hadamard Transform Watermarking

شادرخ سماوي

محمدعلي منتظري، مسعود عمومي