Yigang Zhou

Bio: Yigang Zhou is an academic researcher. The author has contributed to research in topics: Color image & Digital watermarking. The author has an hindex of 1, co-authored 1 publications receiving 14 citations.

Blind Watermarking Algorithm Based on DCT for Color Images

Abstract: Based on luminance and texture masking and frequency sensitivity of human visual system (HVS), a blind watermarking algorithm based on discrete cosine transform (DCT) for color image was proposed. The blue color difference component (Cb) of the color image was 2:1 horizontal down- sampled, and watermark was embedded in the DCT domain by dithering the DCT quantization coefficients. Watermark was first coded by (15,7) Reed-Solomon code, scrambled by spread spectrum code and then embedded in the DCT intermediate frequency coefficients of the host image's Cb component. The experimental results show good results both in watermark transparency and robustness. The algorithm can not only extract watermark blindly but also resist some digital image attacks, such as JPEG compression, noise, filtering, rotating, cropping and rescaling.

A New DCT Based Watermarking Method Using Luminance Component

Abstract: The main purpose of the digital watermarking isto provide information security and copyright protection. Fromthis point of view, a robust blind watermarking method basedon Discrete Cosine Transform for colour images is proposed inthis paper. The proposed method provides hiding a binarywatermark in a compressed Digital Colour Image. First, theDigital Color Image is transformed into YCbCr from RGBcolor space and then the Discrete Cosine Transform middleband of the luminance (Y) component is used for watermarkingprocesses. Each bit of the binary watermark is embedded in adifferent Discrete Cosine Transform block. Thus, deteriorationon the image is minimized achieving high invisibility. Thesituation is checked whether the watermark is lost after theimage saved. If the watermark is lost in any block, the averageof some neighbouring Discrete Cosine Transform coefficients isused for embedding the watermark bit. The experimentalresults show that the proposed method can be safely used whenpoint of interest is binary watermarks. Moreover, extractionprocesses do not need the cover image and the watermark isrecovered completely. Statistical and perceptual qualityevaluations show that the proposed method is better than itscounterparts. DOI: http://dx.doi.org/10.5755/j01.eee.19.4.2015

Luminance-based Embedding Approach for Color Image Watermarking

Abstract: In this paper a new non-blind luminance-based color image watermarking technique is proposed. The original 512×512 color host image is divided into 8×8 blocks, and each block is converted to YCbCr color space. A 32×32 monochrome image is used as a watermark and embedded in the selected blocks of the original image. The selected blocks must have log-average luminance that is closer to the log-average luminance of the image. DCT transform is applied to the Y component of each selected block. Each four values of the watermark image are embedded into each selected block of the host image. The watermark values are embedded in the first four AC coefficients leaving the DC value unchanged. The watermark is extracted from the watermarked image using the same selected blocks and DCT coefficients that have been used in the embedding process. This approach is tested against variety of attacks and filters: such as, highpass, lowpass, Gaussian, median, salt and peppers, and JPEG compression. The proposed approach shows a great ability to preserve the watermark against these attacks.

A robust digital image watermarking scheme based on dwt

Abstract: In this paper a wavelet-based logo watermarking scheme is presented. The logo watermark is embedded into all sub-blocks of the LLn sub-band of the transformed host image, using quantization technique. Extracted logos from all sub-blocks are merged to make the extracted watermark from distorted watermarked image. Knowing the quantization step-size, dimensions of logo and the level of wavelet transform, the watermark is extracted, without any need to have access to the original image.Robustness of the proposed algorithm was tested against the following attacks: JPEG2000 and old JPEG compression, adding salt and pepper noise, median filtering, rotating, cropping and scaling. The promising experimental results are reported and discussed.

A New Robust Color Image Watermarking Scheme Based on 3D-DCT

Abstract: In this paper, for color image copyright protection application, a new and blind color image watermarking algorithm based on quantitation method in three dimensional discrete cosine transform (3D-DCT) is proposed. Firstly, the original RGB color image is divided into non-overlapping blocks sized 8 × 8 × 3, and then performs 3D-DCT transform on each block. Secondly, embed a bit watermarking signal into each block’s 3D-DCT direct-current (DC) coefficient by quantization method. The results show that the proposed scheme has very good imperceptibility and robustness against the common image processing attacks. Compared with similar algorithm, the proposed scheme has better robustness performance for most attacks.