• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.10
• /
• pp.118-125
• /
• 1998

We introduce an adaptive finite state vector quantization using a new side match distortion function. The conventional side match distortion function can make the gray level transition between the block bounddaries as smooth as possible and proper state codebooks in the flat areas where the spatial correlations are high. But it can't make proper codebooks in the edge areas where the spatial correlations are not high. The proposed distortion function adds the variances which represent the image characteristics to the conventional side match distortion function as weighted values. Then it can select better state codebooks than the conventional side match distortion function. Also if it predicts a wrong state, the proposed quantizer can correct the state. As a result, we can obtain the satisfiable image quality.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.6
• /
• pp.1419-1427
• /
• 2007

In this paper, we propose an algorithm which implements a multi-sided side match finite-state vector quantization(MSMVQ). After extracting the edge information from an image and classifying the image into edge blocks or non-edge blocks, we construct an edge map. We subdivide edge blocks into sixteen classes using discrete cosine transform(DCT) AC coefficients. Based on edge map information, a state codebook is made from the master codebook, and side match calculation is done for two-sided or three-sided current block of image. For reducing transmitted bits, a decision is made whether or not to encode the non-edge blocks among the pre-coded blocks by using the master codebook. Also for reducing allocation bits of codeword indices to decoder, a variable length coder is used. Considering the comparison with side match finite-state vector quantization(SMVQ) and two-sided SMVQ(TSMVQ) algorithm about Zelda, Lenna, Bridge and Peppers image, the new algorithm shows better picture quality than SMVQ and TSMVQ respectively.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.12
• /
• pp.153-160
• /
• 2014

The Streganography method for digital images has to insert secret data into the image without image distortion. Side match method is that size of secret data is calculated by difference of embedded pixel value and mean value of side pixels. And the secret value is embedded into the embedded pixel. Therefore, the more secret data increases, the more image distortion increases, too. In this paper, we propose the enhanced method that calculates embedded pixel value by difference of secret value and mean value of side pixels. In proposed method, more secret data is embedded and image distortion has to decreases.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.11
• /
• pp.1329-1340
• /
• 2016

Recently, Zhang proposed a scheme to hide information in encrypted images using synchronous stream ciphers. After the receiver decrypts the encrypted image and extracts data by calculating the spatial correlation property value using the fluctuation function which is designed to calculate spacial correlation between adjacent pixels in a decrypted image. Then, Hong improved the Zhang's data hiding scheme by introducing the side match technique. In this paper, a novel fluctuation function is proposed to reduce the recovery errors which arise during extracting hidden data. Then, we also demonstrated that the proposed fluctuation function outperforms the previous functions through computer simulations for sample images.