Block-based manipulations on transform-compressed images and videos
Multimedia Systems
A DCT-Domain Video Transcoder for Spatial Resolution Downconversion
VISUAL '02 Proceedings of the 5th International Conference on Recent Advances in Visual Information Systems
Image resizing in the discrete cosine transform domain
ICIP '95 Proceedings of the 1995 International Conference on Image Processing (Vol.2)-Volume 2 - Volume 2
A fast approximate algorithm for scaling down digital images in the DCT domain
ICIP '95 Proceedings of the 1995 International Conference on Image Processing (Vol.2)-Volume 2 - Volume 2
Heterogeneous video transcoding to lower spatio-temporalresolutions and different encoding formats
IEEE Transactions on Multimedia
Video transcoding: an overview of various techniques and research issues
IEEE Transactions on Multimedia
Manipulation and compositing of MC-DCT compressed video
IEEE Journal on Selected Areas in Communications
Arbitrary-ratio image resizing using fast DCT of composite length for DCT-based transcoder
IEEE Transactions on Image Processing
Fast algorithms for DCT-domain image downsampling and for inverse motion compensation
IEEE Transactions on Circuits and Systems for Video Technology
A frequency-domain video transcoder for dynamic bit-rate reduction of MPEG-2 bit streams
IEEE Transactions on Circuits and Systems for Video Technology
A fast scheme for image size change in the compressed domain
IEEE Transactions on Circuits and Systems for Video Technology
Local bandwidth constrained fast inverse motion compensation for DCT-domain video transcoding
IEEE Transactions on Circuits and Systems for Video Technology
Drift compensation for reduced spatial resolution transcoding
IEEE Transactions on Circuits and Systems for Video Technology
An efficient arbitrary downsizing algorithm for video transcoding
IEEE Transactions on Circuits and Systems for Video Technology
A Fast Arbitrary Factor Video Resizing Algorithm
IEEE Transactions on Circuits and Systems for Video Technology
A Resizing Algorithm With Two-Stage Realization for DCT-Based Transcoding
IEEE Transactions on Circuits and Systems for Video Technology
The arithmetic cosine transform: exact and approximate algorithms
IEEE Transactions on Signal Processing
Low-complexity 8-point DCT approximations based on integer functions
Signal Processing
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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.