Judul: Penerapan Watermarking untuk Penyisipan Hak Cipta pada Citra Digital dengan Metode Cox
Abstrak: Perkembangan komputer dan perangkat-perangkat lain yang serba digital sekarang ini telah membuat data digital semakin banyak digunakan. Perkembangan tersebut memberikan kemudahan-kemudahan yang mengakibatkan data digital dapat digunakan secara bebas tanpa memperhatikan aspek hak cipta (Intellectual Property Right). Belakangan ini muncul penggunaan steganography untuk mengatasi masalah hak cipta pada data digital yang dikenal dengan istilah watermarking. Watermarking merupakan cara penyembunyian atau penanaman data/informasi tertentu (baik berupa catatan umum maupun rahasia) ke dalam suatu data digital lainnya, dan mampu menghadapi proses-proses pengolahan sinyal digital sampai tahap tertentu. Pada penelitian ini dilakukan proses penyisipan citra digital yang dijadikan watermark ke dalam citra digital yang dijadikan cover image, dimana kedua citra digital tersebut dapat berupa citra RGB maupun grayscale dengan format BMP. Setelah disisipkan, kemudian dibandingkan hasilnya dengan cover image yang asli untuk melihat seberapa besar distorsi yang terjadi. Dari citra yang dihasilkan tersebut dicoba untuk ditarik kembali watermark-nya, lalu dibandingkan dengan watermark yang asli untuk melihat seberapa besar distorsi yang terjadi. Penulis juga mencoba menguji ketahanan metode Cox ini terhadap serangan yang berupa rotasi citra (baik rotasi sebesar 900, 1800, maupun 2700), kompresi JPEG, operasi cropping dan operasi resizing. Untuk mengukur distorsi yang terjadi antara dua buah citra digital, digunakan perhitungan dengan Peak Signal to Noise Ratio (PSNR). Hasil percobaan menunjukkan bahwa metode Cox tidak memberikan pengaruh kualitas citra yang besar pada watermarked image karena didapatkan PSNR rata-rata di atas 30 dB. Jika dibandingkan dengan PSNR yang dihasilkan dari proses kompresi JPEG yang rata-rata sebesar 30- 40 dB, maka hasil tersebut masih dianggap mengalami distorsi yang tidak terlalu besar. Pengaruh metode Cox pada watermark yang ditemu kembalikan dengan watermark yang asli menunjukkan pengaruh yang cukup kecil. Hal ini dapat terlihat dari rata-rata PSNR yang bernilai sebesar 40.8978 dB. Hasil lain dari percobaan ini adalah bahwa metode Cox termasuk tahan terhadap serangan yang berupa rotasi citra (baik rotasi 900, 1800, maupun 2700), akan tetapi kurang tahan terhadap serangan yang berupa kompresi JPEG. Metode Cox ini juga tidak tahan terhadap serangan berupa cropping dan resizing, namun pada kasus resizing dengan memperbesar citra maka watermark masih dapat ditarik kembali jika ukurannya dikembalikan ke ukuran semula terlebih dahulu sebelum watermark ditarik.
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Judul: Perbandingan Teknik Watermark CDMA dalam Domain Spasial dan Domain Wavelet pada Citra Digital
Abstrak: Presentation of data and information has been progressing quite rapidly, so data and information has been widely presented in digital format. Problems began to emerge as widespread digital data need to be protected. This is related to ownership, copyright, or authenticity issues. This study tries to provide solutions to these problems by applying the digital watermarking with Code Division Multiple Access (CDMA) technique. This technique uses a digital image composed of a cover image and two types of watermark (initial and copyright). There are two stages in this research, the first is trying to insert two types of watermark on the cover image in two different domains, namely spatial domain and wavelet domain. Once inserted, the watermark is extracted back to be compared with the original watermark. The second is attempting to insert an initial watermark on the cover image in two different domains, then giving some distortion of the image to be tested for resistance. After that, the watermark is extracted again. From the experiment results, it is known that wavelet domain CDMA is superior in terms of quality of the extracted watermark, processing time, and resistance to distortion (JPEG compression and gamma correction). While CDMA coding spatial domain is simpler and has a resistance to gamma correction only.
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Judul: Phylogeography and Species Limits in the Papuan White Snake (Micropechis ikaheka) (Reptilia: Serpentes: Elapidae)
Abstrak: Papua white snake, Micropechis ikaheka, has been distingushed into two subspecies M.i. ikaheka and M.i. fasciatus. However, due to lack of data on their morphology, distribution and ecology, both subspecies often ignored in scintific discussions and refers only byas , Micropechis ikaheka. This study was designed to document the differences between M.i. ikaheka and M.i fasciatus by using scales characteristics and reproductive organ or hemipenes. The study also examine, zoogeography, habitat, diet and cannibalism of both subspecies to better understanding the the ecology of one of the most venomous snakes in the world. This study consists of three topics with method and also different in the size samples, respectively. The first study is the histology and microtopography of the skin were studied using paraffin method and Scanning Electron Microscope (SEM). The second is the hemipenis were examined by following Myers and Cadle (2003), and Zaher and Prudente (2003). The third is the abdominal surgery was carried out to document diet type and the investigate phenomenon of cannibalism in the snake. Specimens for this study came from the collection from Museum Zoologicum Bogoriense (MZB) and Universitas Negeri Papua’s Laboratory (LZU). The research result also indicated that the markers of skin and hemipenis described the same structure and microornamentation in all M. ikaheka groups being compared. Based specimens examined morphological descriptions do not s support the further differentiation in Micropechis. In short, two markers that used in this study could not sufficiently indicate the differences in the level of species and subspecies of M. ikaheka. The study, however, were able to delineate zoogeography and skin color patterns, which fall into four groups: M. i. ikaheka; M. i. fasciatus. M. i. ssp. “intermediate”; and M. i. ssp “black”. This study also revealed that color variations did not overlap in their geographic distribution. It is therefore, it suggested that environmental factors may contribute to the skin color variations. It also assumed that habitat discontinuous and biogeography factors may also cause the loss of the connection between the original populations (vicarians) or follow colonization events (dispersal). The examined of 22 stomach contents of M. ikaheka shows this species is carnivorous, and prey on vertebrates such as amphibians, fish, reptiles, and Mammals. These snakes are opportunistic predators since they prey on all that can be captured, but mainly reptiles (61.5%), followed by mammals and fish (both 15.4%), and amphibians (7.7%). Although categorized as terrestrial animal, the diet study showed that M. ikaheka snakes often go into the water to hunt for fish (the sample from Yapen island), including eel (the sample from Aru island). Based on prey items indentified, there is evidence that M. ikaheka is cannibal. At this time, there still no record on reason for cannibalism, but it is assumed that cannibalism was due to competition between populations and means to control population.
Keyword: geographic variation, white snake, papua