A new color image compression technique based on moment-preserving and block truncation coding is proposed, An input image is divided into nonoverlapping blocks and each block pixel is assigned one of two representati...
详细信息
A new color image compression technique based on moment-preserving and block truncation coding is proposed, An input image is divided into nonoverlapping blocks and each block pixel is assigned one of two representative colors, which are computed with analytic formulas derived from preserving certain moments in the block. A bit map is then generated for each block to represent the pixels' colors, Different uniformity conditions in the representative colors are also identified and utilized to save code bits, Good average compression ratios up to about 13 can be achieved, as shown by experimental results.
block truncation coding (ETC) is an efficient tool for image compression, To compress color-pixel blocks, a novel color ETC algorithm, called quaternion-moment block truncation coding (QMBTC), is presented in this pap...
详细信息
block truncation coding (ETC) is an efficient tool for image compression, To compress color-pixel blocks, a novel color ETC algorithm, called quaternion-moment block truncation coding (QMBTC), is presented in this paper, Analytical formulas for QMBTC, whose computation time is on the order of pixel block size, are derived by using quaternion arithmetic and the moment-preserving principle, The proposed color ETC algorithm can adaptively truncate a pixel block into one or two output classes according to the distribution of color values inside the blocks, The experimental results show that the compression ratio is increased as compared with existing color ETC algorithms, and the picture quality of reconstructed images is satisfactory, In addition, a post-ETC data compression scheme is proposed to further compress the subimage constructed by reproduction colors of truncated pixel blocks, Using a lookup table to display decoded data, this postprocessing scheme can output images acceptable to human eyes.
A hybrid block truncation coding (BTC) is presented in this work. In the hybrid ETC, a universal codebook using Ramming codes and a differential pulse code modulation (DPCM) are employed, respectively, to the bit plan...
详细信息
A hybrid block truncation coding (BTC) is presented in this work. In the hybrid ETC, a universal codebook using Ramming codes and a differential pulse code modulation (DPCM) are employed, respectively, to the bit plane and the side information of ETC to reduce coding rate. Simulation results reveal that the performance of the proposed algorithm is only slightly worse than that of the hybrid ETC using vector quantization (VQ) techniques, but with much lower computational or hardware complexity.
A new algorithm of classified vector quantization based on quadtree segmentation is proposed. It can obtain lower bit rate and overcome edge degradation. Simulation results show that the better subjective image qualit...
详细信息
A new algorithm of classified vector quantization based on quadtree segmentation is proposed. It can obtain lower bit rate and overcome edge degradation. Simulation results show that the better subjective image quality can also be obtained when bitrate is lower than 0.25 bpp. Comparing with JPEG, the improvement of the peak signal-to-noice ratio (PSNR) is up to 2 dB at the same bit rate.
In this letter, a new scheme of designing two-level minimum mean square error quantizer for image coding is proposed. Genetic algorithm is applied to achieve this goal. Comparisons of results with various methods have...
详细信息
In this letter, a new scheme of designing two-level minimum mean square error quantizer for image coding is proposed. Genetic algorithm is applied to achieve this goal. Comparisons of results with various methods have verified, the proposed method can reach nearly optimal quantization with only less iterations.
A new algorithm of classified vector quantization based on quadtree segmentation is proposed. It can obtain lower bit rate and overcome edge degradation. Simulation results show that the better subjective image qualit...
详细信息
A new algorithm of classified vector quantization based on quadtree segmentation is proposed. It can obtain lower bit rate and overcome edge degradation. Simulation results show that the better subjective image quality can also be obtained when bitrate is lower than 0.25 bpp. Comparing with JPEG, the improvement of the peak signal to-noice ratio (PSNR) is up to 2 dB at the same bit’rate.
The method of block truncation coding (BTC) was originally proposed by Delp and Mitchell and later extended to color images by others. The idea is to retain important visual features while discarding details which are...
详细信息
ISBN:
(纸本)0819421324
The method of block truncation coding (BTC) was originally proposed by Delp and Mitchell and later extended to color images by others. The idea is to retain important visual features while discarding details which are not to be noticeable to human observers. In our paper, we further explore the block truncation coding method by minimizing the within group variance measure proposed by Otsu and the information distance suggested by Kullback to divide every 4 by 4 subimage into two classes, and an intuitive vector quantizer to further compress the coded output. As a result of the combined application of BTC and vector quantization methods, we get better bit rates (bits per pixel) for the test image used in experiments without significant perceivable errors in its appearance. First, we divide a color image into 4 by 4 small nonoverlapping blocks. The Otsu or Kullback thresholding technique is then used as an optimal method to minimize the mean square error of classifying each pixel in a block into two classes and encode it in one-bit adaptive vector quantizer. After classification, for each 4 by 4 block, there is a bitmap corresponding to one-bit adaptive vector quantizer and a six-dimensional mean vector corresponding to each of the two classes. In the second part, the vector quantizer proposed by Linde, Buzo and Gary (known as LBG) is used to compress the bit-map and mean vectors separately. This is a six- dimensional signal compression for the mean vectors and a binary compression for the bitmap. Vector quantization of these BTC output results in a reduction of the bit rate of the coder. By using BTC and vector quantization methods, we have obtained 1.0 bit/pixel compression result for a color image of size 512 by 480 given with 8 bits/pixel and R, G, B specifications. The mean square error was also measured as low as 0.07 without much deformation in the reconstructed image.
Two simple and fast block truncation coding algorithms which require reduced bit rates are presented in this paper. The proposed algorithms are compared with the modified block truncation coding technique (MBTC) with ...
详细信息
Two simple and fast block truncation coding algorithms which require reduced bit rates are presented in this paper. The proposed algorithms are compared with the modified block truncation coding technique (MBTC) with regard to the mean square error (MSE), bit rates and subjective quality of the reconstructed images, It is found that the results obtained with the proposed algorithms at reduced bit rates are comparable to those obtained with the MBTC. Further, it is shown that one of the proposed algorithms yields results which are comparable to those achieved with more complex hybrid algorithms.
This paper presents a modified block truncation coding scheme for the compression of images. We first design a set of binary edge patterns, which are visually significant, to approximate the bit plane of an image bloc...
详细信息
This paper presents a modified block truncation coding scheme for the compression of images. We first design a set of binary edge patterns, which are visually significant, to approximate the bit plane of an image block. An interblockcoding scheme, utilizing the spatial correlation between neighboring blocks, is then developed for coding of the sample mean and standard deviation of a block. Simulation results indicate that the bit rate is significantly reduced without introducing noticeable degradation in the reconstructed images.
VQ-BTC is a recent technique used in the coding of image data to combat edge degradation produced by vector quantisation (VQ) or block truncation coding (BTC). However, it has high encoding complexity and needs a larg...
详细信息
VQ-BTC is a recent technique used in the coding of image data to combat edge degradation produced by vector quantisation (VQ) or block truncation coding (BTC). However, it has high encoding complexity and needs a large amount of memory to store 31 codebooks at both the encoder and decoder. A modified VQ-BTC (MVQ-BTC) algorithm is presented which achieves a performance close to that of VQ-BTC, but needs only three codebooks, and requires less computation time than VQ-BTC.
暂无评论