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An Efficient Method for DCT-Domain Image Resizing with Mixed Field/Frame-Mode Macroblocks

An Efficient Method for DCT-Domain Image Resizing with Mixed Field/Frame-Mode Macroblocks. Changhoon Yim and Michael A. Isnardi IEEE TRANSACTION ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 9, NO. 5, AUGUST 1999. Outline. Introduction DCT-Domain Image Resizing

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An Efficient Method for DCT-Domain Image Resizing with Mixed Field/Frame-Mode Macroblocks

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  1. An Efficient Method for DCT-Domain Image Resizing with Mixed Field/Frame-Mode Macroblocks Changhoon Yim and Michael A. Isnardi IEEE TRANSACTION ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 9, NO. 5, AUGUST 1999

  2. Outline • Introduction • DCT-Domain Image Resizing • Decomposition of DCT-Domain Image Resizing Operation • Proposed DCT-Domain Image Resizing Method • Discussion on DCT-Domain Filtering • Experimental Result • Conclusion

  3. Introduction • Many image and video compression standards such as JPEG, MPEG-1, MPEG-2, and H.261 are based on DCT coding techniques. • In MPEG-2, there are field and frame pictures to accommodate coding of progressive and interlaced video. • Previous DCT-domain image resizing methods assume that all macroblocks are in the frame mode.

  4. Field and frame mode of a macroblock in the spatial domain

  5. DCT-Domain Image Resizing : Four Steps • Low-pass filtering in the DCT domain • Inverse DCT • 2 : 1 downsampling • Forward DCT

  6. DCT-Domain Image Resizing : Matrices DCT transform matrix Downsampling matrix Low-pass filter

  7. Decomposition of DCT-Domain Image Resizing Operation

  8. Inverse DCT for a DCT block

  9. Downsampling in the spatial domain

  10. Proposed DCT-Domain Image Resizing Method

  11. Frame- and Field-mode resizing transformation matrices

  12. Discussion on DCT-Domain Filtering (1) • Previous methods are simple low-pass filtering by truncation in DCT domain • The matrix is not equivalent to sharp low-pass filter in DFT domain, and dose not correspond to a liner convolution in the spatial domain • May produce visible aliasing and blocking artifacts • Affect differently the field- and frame-mode in spatial domain may result in serious blocking artifacts between field- and frame-mode macroblocks

  13. Discussion on DCT-Domain Filtering (2) • The implicit low-pass filtering operation as averaging by the downsampling matrices would be a good compromise for block-based DCT-domain image resizing • Would not have any blocking artifact • The filtering characteristics should be the same for field- and frame-mode macroblocks

  14. Experimental Results (1)

  15. Experimental Results (2)

  16. Experimental Results (3)

  17. Conclusion • Propose method can handle field-mode • Avoid the blocking artifacts and the difference in the characteristics between field- and frame-mode macroblocks • Future research could be performed for more efficient for low-pass filtering in the DCT domain for DCT-domain image resizing

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