A DCT-Domain Video Transcoder for Spatial Resolution Downconversion
VISUAL '02 Proceedings of the 5th International Conference on Recent Advances in Visual Information Systems
Configurable implementation of parallel memory based real-time video downscaler
Microprocessors & Microsystems
Efficient hybrid DCT-domain algorithm for video spatial downscaling
EURASIP Journal on Advances in Signal Processing
Layered image resizing in compression domain
Image Communication
An Adaptive Image Resizing Algorithm in DCT Domain
IEICE - Transactions on Information and Systems
In-network adaptation of video streams using network processors
Advances in Multimedia
Manipulating lossless video in the compressed domain
MM '09 Proceedings of the 17th ACM international conference on Multimedia
Adaptive up-sampling method using DCT for spatial scalability of scalable video coding
IEEE Transactions on Circuits and Systems for Video Technology
Down-sampling design in DCT domain with arbitrary ratio for image/video transcoding
IEEE Transactions on Image Processing
A fast arbitrary-ratio downscaling algorithm for video transcoding
SIP '07 Proceedings of the Ninth IASTED International Conference on Signal and Image Processing
Adaptive DCT-Domain Down-Sampling and Learning Based Mapping for Low Bit-Rate Image Compression
PCM '09 Proceedings of the 10th Pacific Rim Conference on Multimedia: Advances in Multimedia Information Processing
Direct splitting and merging of 2-D DCT in the DCT domain
Digital Signal Processing
Transcoding with Resolution Conversion Using Super-Resolution and Irregular Sampling
Journal of Signal Processing Systems
An efficient compressed domain spatial transcoding scheme for adaptive video content delivery
PCM'10 Proceedings of the Advances in multimedia information processing, and 11th Pacific Rim conference on Multimedia: Part II
Image filtering in the compressed domain
ICVGIP'06 Proceedings of the 5th Indian conference on Computer Vision, Graphics and Image Processing
An integrated approach for downscaling MPEG video
ICVGIP'06 Proceedings of the 5th Indian conference on Computer Vision, Graphics and Image Processing
Transrating-assisted MPEG-4 video resizing with rate-distortion optimization
Proceedings of the 10th International Conference on Advances in Mobile Computing & Multimedia
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Given a video frame in terms of its 8×8 block-DCT coefficients, we wish to obtain a downsized or upsized version of this frame also in terms of 8×8 block-DCT coefficients. The DCT being a linear unitary transform is distributive over matrix multiplication. This fact has been used for downsampling video frames in the DCT domain. However, this involves matrix multiplication with the DCT of the downsampling matrix. This multiplication can be costly enough to trade off any gains obtained by operating directly in the compressed domain. We propose an algorithm for downsampling and also upsampling in the compressed domain which is computationally much faster, produces visually sharper images, and gives significant improvements in PSNR (typically 4-dB better compared to bilinear interpolation). Specifically the downsampling method requires 1.25 multiplications and 1.25 additions per pixel of original image compared to 4.00 multiplications and 4.75 additions required by the method of Chang et al. (1995). Moreover, the downsampling and upsampling schemes combined together preserve all the low-frequency DCT coefficients of the original image. This implies tremendous savings for coding the difference between the original frame (unsampled image) and its prediction (the upsampled image). This is desirable for many applications based on scalable encoding of video. The method presented can also be used with transforms other than DCT, such as Hadamard or Fourier