This paper presents an approach for identifying recaptured image based on DCT coefficients. The low frequency of an image mainly reflect such information as texture and profile details. The difference between real live face images and recaptured images can be described by the low frequency of DCT coefficients. Characterized by the features of the simple and low complexity, DCT Transformation ca...

The algorithm represents the DCT coefficients to concentrate signal energy and proposes combination and dictator to eliminate the correlation in the same level subband for encoding the DCT-based images. This work adopts DCT and modifies the SPIHT algorithm to encode DCT coefficients. The proposed algorithm also provides the enhancement function in low bit rate in order to improve the perceptual...

The discrete cosine transform (DCT) is widely used in image and video coding schemes. By applying the DCT to image blocks and quantizing the DCT coefficients, efficient image compression can be achieved. However, the quantization of the DCT coefficients introduces errors in the decompressed images, which appear as blocky artifacts. The blocky artifacts can be converted into “Gaussian-type” nois...

In this paper, a simple image steganography for secure communication is proposed. Our scheme is based on the discrete cosine transformation (DCT) technique. By using DCT, the most signifi cant information of each DCT secret block can be embedded into the non-signifi cant parts of each DCT cover block. To improve the image quality of the cover image, a quantization factor is used. According to o...

A method for efficient spatial domain filtering, directly in the discrete cosine transform (DCT) domain, is developed and proposed. It consists of using the discrete sine transform (DST) and the DCT for transform-domain processing on the in JPEG basis of the previously derived convolution-multiplication properties of discrete trigonometric transforms. The proposed scheme requires neither zero p...

DCT-based transformed domain watermarking algorithm has some flaws In the aspects of embedding position, embedding strength and embedding method, which have an important influence on watermarking embedding and watermarking extracting. In this paper we discussed these key techniques on DCT-based transformed domain watermarking algorithm and spatial domain digital watermarking algorithm, and thei...

Filtering is an important issue in signals and images processing. Many images and videos are compressed using discrete cosine transform (DCT). For reducing the computation complexity, we are interested in filtering block and images directly in DCT domain. This article proposed an efficient and yet very simple filtering method directly in DCT domain for any symmetric, asymmetric, separable, inse...

Although most of the proposals for implementing motion-compensated temporal filtering (MCTF) schemes are based on the wavelet transform, in this paper, we propose an MCTF framework based on the discrete cosine transform (DCT). Using DCT decimation and interpolation, several temporal decomposition structures named motion-compensated DCT temporal filters (MCDCT-TF) are introduced. These structure...

The shape-adaptive DCT (SA-DCT) can be computed on a support of arbitrary shape, but retains a computational complexity comparable to that of the usual separable block DCT. Despite the near-optimal decorrelation and energy compaction properties, application of the SA-DCT has been rather limited, targeted nearly exclusively to video compression. It has been recently proposed by the authors to em...

This paper presents a general framework for maximally decimated modulated filter banks. The theory covers the known classes of cosine modulation and relates them to complexmodulated filter banks. The prototype filters have arbitrary lengths, and the overall delay of the filter bank is arbitrary, within fundamental limits. Necessary and sufficient conditions for perfect reconstruction (PR) are d...