关键词: 离散余弦变换, 量化, 图像压缩

Abstract: The Discrete Cosine Transform（DCT） has become more and more popular in practical digital image process.In general，the most useful coefficients of the DCT concentrate in the low frequency orders.It is consuming time and increasing calculation for the calculation of zero coefficients.According to the characteristic of the quantized coefficients，two new optimized algorithms are proposed for the computation of a 2-D discrete cosine transform in this paper.The calculation of coefficients of a 8×8 DCT only need 32 multiplications and 108 additions.The total number of multiplications is reduced 60%，and the total number of additions is reduced 77%.The results show that for practical situations，significant computation reductions can be achieved while causing negligible PSNR degradation.

Key words: Discrete Cosine Transform（DCT）, quantization, image compression