基于三维离散余弦变换的静止彩色图象压缩

Still color Image Compression Based on 3-D DCT

为了既能获得较高的压缩比 ,又能保证较好的图象质量 ,提出了一种基于三维离散余弦变换 (3D DCT)的静止彩色图象编码方法 .在此算法中 ,首先将原始图象分割成互不覆盖的 8× 8子块 ;然后根据局部能量的大小将各子块分为 4类 ,再把属于同一类的子块组合到一起 ,形成三维立方体并对三维立方体进行三维离散余弦变换 ,从而提高压缩效率 .计算机模拟结果表明 ,此算法在压缩比高于 4 0时 ,其平均峰值信噪比约为 2 9d B,解压后的图象质量有较高的保真度 ,在同等情况下 ,其比 JPEG标准提高约 5 d

In this paper, A three dimensional discrete cosine transform(3D DCT) coder for still color images is presented, which can not only achieve high compression ratio but also ensure good image quality. In the proposed method, the original image is splitted into non overlapped 8×8 blocks and segments subblocks of the image into four different classes based on local energy magnitude. Then those subblocks with the same class are gathered to form 3D cuboids, and employs 3D DCT to the 3D cuboids. This improves the efficiency of compression.Computer simulation results show that the PSNR (average Peak Signal Noise Ratio) of reconstructed images achieve 29dB with high fidelity when the compression ratios are higher than 40. Compared to JPEG, it advances more than 5dB in the same situation. The proposed method achieves higher fidelity of decoded images than by JPEG.