A Color Image Watermarking Scheme Based On QR Factorization, Logistic and Lorentz Chaotic Maps

Most of the existing color image watermarking schemes use grayscale or binary image as watermark because color image watermark has more data than grayscale or binary watermark. Therefore, it is a challenging issue to design a color image-watermarking scheme. This paper proposes a novel color image watermarking scheme to embed color image watermark into color host image. In watermarking schemes, first divide the host and watermark image into non-overlapping blocks, apply the Discrete Cosine Transformation (DCT) on each blocks of both watermark, and host image. After that QR Factorization, apply on the each blocks of watermark. In this paper, Logistic and Lorentz chaotic maps are usedfor estimating the embedding strength and location. The experimental results reveal that this watermarking scheme is robust against different image processing attacks viz. cropping, contrast adjustment and coloring

Integrasi Discrete Wavelet Transform dan Singular Value Decomposition pada Watermarking Citra untuk Perlindungan Hak Cipta

Tren masalah watermarking pada sekarang ini adalah bagaimana mengoptimalkan trade-off antara imperceptibility (visibilitas) citra ter-watermark terhadap pengaruh distorsi dan robustness terhadap penyisipan watermark. Masalah menggunakan kekuatan penyisipan berdasarkan Single Scaling Factor (SSF) atau Multiple Scaling Factor (MSF) juga ditemukan. Penelitian ini mengusulkan metode penyisipan watermark untuk perlindungan hak cipta pada citra dan algoritma ekstraksi citra ter-watermark yang dioptimalkan dengan penggabungan Discrete Wavelet Transform (DWT) dan Singular Value Decomposition (SVD). Nilai-nilai singular dari LL3 koefisien sub-band dari citra host dimodifikasi menggunakan nilai tunggal citra watermark biner menggunakan MSFs. Kontribusi utama dari skema yang diusulkan adalah aplikasi DWT-SVD untuk mengidentifikasi beberapa faktor skala yang optimal. Hasil penelitian menunjukkan bahwa skema yang diusulkan menghasilkan nilai Peak Signal to Noise Ratio (PSNR) yang tinggi, yang menunjukkan bahwa kualitas visual gambar yang baik pada masalah citra watermarking telah mengoptimalkan trade-off. Trade-off antara imperceptibility (visibilitas) citra ter-watermark terhadap pengaruh distorsi dan robustness citra ter-watermark terhadap operasi pengolahan citra. Nilai PSNR yang didapat pada citra yang diujikan: baboon=53,184; boat=53,328; cameraman=53,700; lena=53,668; man=53,328; dan pepper sebesar 52,662. Delapan perlakuan khusus pada hasil citra ter-watermark diujikan dan diekstraksi kembali yaitu JPEG 5%, Noise 5%, Gaussian filter 3x3, Sharpening, Histogram Equalization, Scaling 512-256, Gray Quantitation 1bit, dan Cropping 1/8. Hasil dari perlakuan khusus kemudian diukur nilai Normalized Cross-Correlation (NC) yang menghasilkan rata-rata semua citra diperoleh sebesar 0,999 dari satu. Hasil penelitian dari metode yang diusulkan lebih unggul nilai PSNR dan NC dari penelitian sebelumnya. Jadi dapat disimpulkan bahwa penerapan dengan metode DWT-SVD ini mampu menghasilkan citra yang robust namun memiliki tingkat imperceptibility yang cukup tinggi

An enhanced method based on intermediate significant bit technique for watermark images

Intermediate Significant Bit digital watermarking technique (ISB) is a new approved technique of embedding a watermark by replacing the original image pixels with new pixels. This is done by ensuring a close connection between the new pixels and the original, and at the same time, the watermark data can be protected against possible damage. One of the most popular methods used in watermarking is the Least Significant Bit (LSB). It uses a spatial domain that includes the insertion of the watermark in the LSB of the image. The problem with this method is it is not resilient to common damage, and there is the possibility of image distortion after embedding a watermark. LSB may be used through replacing one bit, two bits, or three bits; this is done by changing the specific bits without any change in the other bits in the pixel. The objective of this thesis is to formulate new algorithms for digital image watermarking with enhanced image quality and robustness by embedding two bits of watermark data into each pixel of the original image based on ISB technique. However, to understand the opposite relationship between the image quality and robustness, a tradeoff between them has been done to create a balance and to acquire the best position for the two embedding bits. Dual Intermediate Significant Bits (DISB) technique has been proposed to solve the existing LSB problem. Trial results obtained from this technique are better compared with the LSB based on the Peak Signal to Noise Ratio (PSNR) and Normalized Cross Correlation (NCC). The work in this study also contributes new mathematical equations that can study the change on the other six bits in the pixel after embedding two bits