| 引用本文: | 陈波,成礼智,王红霞.基于快速方向重叠变换的图像压缩.[J].国防科技大学学报,2009,31(5):54-57.[点击复制] |
| CHEN Bo,CHENG Lizhi,WANG Hongxia.Fast Directional Lapped Transform Based Image Compression[J].Journal of National University of Defense Technology,2009,31(5):54-57[点击复制] |
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| 基于快速方向重叠变换的图像压缩 |
| 陈波, 成礼智, 王红霞 |
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(国防科技大学 理学院，湖南 长沙 410073)
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| 摘要: |
| 传统二维DCT无法稀疏表示除水平或垂直方向外的边缘，而具有强方向表示能力的方向预测离散余弦变换(DPDCT)计算复杂度过高。针对这些问题，快速方向重叠变换(FDLT)沿给定的方向模式进行变换，避免了DPDCT中的插值运算，并进一步集中分散在变换块间的能量，可以快速、稀疏地表示图像中各向异性边缘信息。此外，FDLT通过设计块边界提升，保证了算法完全重构。实验表明，FDLT计算复杂度不超过DCT的2倍。采用同样的编码方法，基于FDLT的压缩图像与基于DCT的压缩图像相比，峰值信噪比可提高0.5dB以上，而且图像边缘细节更加清晰、完整。 |
| 关键词: 图像压缩 方向变换 离散余弦变换 重叠变换 |
| DOI： |
| 投稿日期：2009-02-16 |
| 基金项目:国家自然科学基金资助项目(10601068)，国防科技大学校基金资助项目(0806) |
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| Fast Directional Lapped Transform Based Image Compression |
| CHEN Bo, CHENG Lizhi, WANG Hongxia |
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(College of Science, National Univ. of Defense Technology, Changsha 410073, China)
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| Abstract: |
| Traditional discrete cosine transform (DCT) can only sparsely represent the horizontal and vertical edges in images, and the computation complexity of directional prediction DCT (DPDCT), which is of ability to represent more directions, is much higher. To overcome these shortcomings, the fast directional lapped transforms (FDLT) is proposed, in which the transform is performed on the predefined direction mode and the energy in edges lying across blocks is compacted further. In Comparison with DPDCT, FDLT needs no interpolation. So FDLT can sparsely represent the anisotropic edges in images much faster. Furthermore, special lifting algorithm is designed to ensure the perfect reconstruction. The computation of FDLT is no more than 2 times of DCT's. Coding with the same set partition method, PSNR of images compressed with FDLT is 0.5dB higher than that with DCT. FDLT based compression also achieves clearer edges and details in the reconstructed images. |
| Keywords: image compression directional transform discrete cosine transform(DCT) lapped transform |
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