Abstract

All phase digital filter (APDF) is a new type of linear phase FIR digital filter that was proposed in recent years. Firstly, the theory of biorthogonal wavelet transform and windowed APDF based on DCT is expounded and the relationship between them is discussed. Secondly, a novel algorithm is proposed to implement biorthogonal wavelet transform by using windowed APDF based on DCT. As an important application of biorthogonal wavelet transform, multi-resolution analysis of 2-D image signal could be used to test the feasibility and applicability of the proposed algorithm. Finally, the simulation results using MATLAB tool are shown in this paper and the analysis indicates that the proposed method performs well.

In watermarking schemes, the discrete wavelet transform (DWT) is broadly used because its frequency component separation is very useful. Moreover, LU decomposition has little influence on the visual quality of the watermark. Hence, in this paper, a novel blind watermark algorithm is presented based on LU transform and DWT for the copyright protection of digital images. In this algorithm, the color host image is first performed with DWT. Then, the horizontal and vertical diagonal high frequency components are extracted from the wavelet domain, and the sub-images are divided into 4×4 non-overlapping image blocks. Next, each sub-block is performed with LU decomposition. Finally, the color image watermark is transformed by Arnold permutation, and then it is inserted into the upper triangular matrix. The experimental results imply that this algorithm has good features of invisibility and it is robust against different attacks to a certain degree, such as contrast adjustment, JPEG compression, salt and pepper noise, cropping, and Gaussian noise.

No abstract

Color filter array (CF A) interpolation is the integral part of image processing for single sensor digital cameras. In this paper, we present a novel algorithm based on directional weighting and adaptive edge detection. We evaluate the edges by using improved edge detection method and estimate the missing color values in different directions. By calculating differences of directional gradients, the threshold will be determined when we calculate the pixel values according to weighting coefficients. Experimental results show that the proposed method yields visually pleasant results and outperforms existing demosaicking methods in composite peak signal-to-noise ratio (CPSNR). In addition, the computational complexity of the proposed method is comparable to the existing methods.