Direct N-point DCT computation from three adjacent N/3-point DCT coefficients

An efficient method for computing a length-N Discrete Cosine Transform (DCT) from three consecutive length-N/3 DCTs is proposed. This method differs from previous ones in that it reduces considerable 31-38% arithmetic operations and uses only length-N/3 DCTs instead of length-N DCTs. We also find its great applications in fractional scaling of a block DCT-based image by the factor of 1/2/sup /spl alpha//3/sup /spl beta//. This would be very useful in high-definition television (HDTV) standard, whose display size is usually 16:9. The comparison with conventional methods is provided.

[1]  Wan-Chi Siu,et al.  Fast radix-3/6 algorithms for the realization of the discrete cosine transform , 1992, [Proceedings] 1992 IEEE International Symposium on Circuits and Systems.

[2]  Athanassios N. Skodras.  Direct transform to transform computation , 1999, IEEE Signal Processing Letters.

[3]  Mohan S. Kankanhalli,et al.  Fractional scaling of image and video in DCT domain , 2003, Proceedings 2003 International Conference on Image Processing (Cat. No.03CH37429).

[4]  Athanassios N. Skodras.  Fast discrete cosine transform pruning , 1994, IEEE Trans. Signal Process..

[5]  Guoan Bi,et al.  DCT algorithms for composite sequence lengths , 1998, IEEE Trans. Signal Process..

[6]  Chi-Wah Kok,et al.  Fast algorithm for computing discrete cosine transform , 1997, IEEE Trans. Signal Process..

[7]  Hyun Wook Park,et al.  L=M -Fold Image Resizing in Block-DCT Domain Using Symmetric Convolution , 2001 .

[8]  Wan-Chi Siu,et al.  Mixed-radix discrete cosine transform , 1993, IEEE Trans. Signal Process..