tailieunhanh - Báo cáo hóa học: " Research Article Efficient Hybrid DCT-Domain Algorithm for Video Spatial Downscaling"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Efficient Hybrid DCT-Domain Algorithm for Video Spatial Downscaling | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 57291 16 pages doi 2007 57291 Research Article Efficient Hybrid DCT-Domain Algorithm for Video Spatial Downscaling Nuno Roma and Leonel Sousa INESC-ID IST TULisbon Rua Alves Redol 9 1000-029 Lisboa Portugal Received 30 August 2006 Revised 16 February 2007 Accepted 6 June 2007 Recommended by Chia-Wen Lin A highly efficient video downscaling algorithm for any arbitrary integer scaling factor performed in a hybrid pixel transform domain is proposed. This algorithm receives the encoded DCT coefficient blocks of the input video sequence and efficiently computes the DCT coefficients of the scaled video stream. The involved steps are properly tailored so that all operations are performed using the encoding standard block structure independently of the adopted scaling factor. As a result the proposed algorithm offers a significant optimization of the computational cost without compromising the output video quality by taking into account the scaling mechanism and by restricting the involved operations in order to avoid useless computations. In order to meet any system needs an optional and possible combination of the presented algorithm with high-order AC frequency DCT coefficients discarding techniques is also proposed providing a flexible and often required complexity scalability feature and giving rise to an adaptable tradeoff between the involved scalable computational cost and the resulting video quality and bit rate. Experimental results have shown that the proposed algorithm provides significant advantages over the usual DCT decimation approaches both in terms of the involved computational cost the output video quality and the resulting bit rate. Such advantages are even more significant for scaling factors other than integer powers of 2 and may lead to quite high PSNR gains. Copyright 2007 N. Roma and L. Sousa. This is an open access article distributed .