Prior to compression the input RGB full-color image I RGB , traditional chroma subsampling on the converted YUV image I YUV is an important operation. In this thesis, we propose an improved chroma 4:2:2 subsampling-first DCT-based chroma subsampling and luma modification method for I RGB. First, based on bilinear interpolation upsampling, we propose an improved chroma 4:2:2 subsampling scheme to subsample the chroma image I UV, after solving the derived over-determined system to
obtain the best subsampled pixel values. Next, we perform a discrete cosine transform (DCT) on each 16 × 8 chroma block in the subsampled UV image, and then, for each 16 × 8 DCT coefficient block, only half of the DCT coefficients are preserved. Furthermore, we perform an inverse DCT on the 16 × 8 DCT block, in which the lower part of the block is padded by zero. Finally, based on the reconstructed RGB full-color pixel-distortion minimization criteria, we modified the luma pixel values. Based on the IMAX, Kodak, and SCI datasets, on the JPEG platform, the comprehensive experimental data demonstrated the substantial quality and quality-bitrate tradeoff merits of the reconstructed RGB full-color images by our method relative to the traditional and state-of-the-art chroma subsampling methods.

[1] G. Bjφntegaard, Calculation of Average PSNR Difference Between RD-Curves, Austin, TX, USA, document VECG-M33, Apr. 2001.
[2] K.-L. Chung, T.-C. Hsu, and C.-C. Huang, “Joint chroma subsampling and distortion-minimization-based luma modification for RGB color images with application,” IEEE Transactions on Image Processing, vol. 26, no. 10, pp. 4626–4638, Oct. 2017.
[3] K. L. Chung, T. Y. Liu, and J. S. Cheng, “Novel and Optimal Luma Modification-Based Chroma Downsampling for Bayer Color Filter Array Images,” Technique Report, Department of Computer Science and Information Engineering, National Taiwan University of Science and Technology, Dec. 2019.
[4] B. N. Datta, Numerical Linear Algebra and Applications, First ed., CA., USA: pp. 315–324, 1995. Brooks/Cole Publishing Company.
[5] R. Dugad and N. Ahuja, “A fast scheme for image size change in the compressed domain,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 11, no. 4, pp. 461–474, Apr. 2001.
[6] D. Flynn et al., “Overview of the Range Extensions for the HEVC Standard: Tools, Profiles, and Performance,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 26, no. 1, pp. 4–19, Jan. 2016.
[7] T. Frajka and K. Zeger, “Downsampling dependent upsampling of images,” Signal Processing Image Community, vol. 19, no. 3, pp. 257–265, Mar. 2004.
[8] IMAX image database. Accessed on: Apr. 28, 2020. [Online]. Available: https://www4.comp.polyu.edu.hk/∼cslzhang/CDM Dataset.htm.
[9] Kodak image database. Accessed on: Apr. 28, 2020. [Online]. Available: http://www.cs.albany.edu/∼xypan/research/snr/Kodak.html.
[10] H. M. Kim, W. S. Kim, and D. S. Cho, “A new color transform for RGB coding,”2004 International Conference on Image Processing, 2004. ICIP ’04., Singapore, 2004, pp. 107–110 Vol. 1.
[11] X. Li and M. T. Orchard, “New edge-directed interpolation,” IEEE Transactions on Image Processing, vol. 10, no. 10, pp. 1521–1527, Oct. 2001.
[12] C. H. Lin, K. L. Chung, and C. W. Yu, “Novel chroma subsampling strategy based on mathematical optimization for compressing mosaic videos with arbitrary RGB color filter arrays in H.264/AVC and HEVC,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 26, no. 9, pp. 1722–1733, Sep. 2016.
[13] Y. Lu, S. Li, and H. Shen, “Virtualized screen: A third element for cloud-mobile convergence,” IEEE Multimedia Magazine, vol. 18, no. 2, pp. 4–11, Feb. 2011.
[14] V. Menezes, S. K. Nandy, and B. Mitra, “Signal compression through spatial frequency-based motion estimation,” Integration, the VLSI journal, vol. 22, pp. 115–135, Aug. 1997.
[15] Z. Pan, H. Shen, Y. Lu, S. Li, and N. Yu, “A low-complexity screen compression scheme for interactive screen sharing,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 23, no. 6, pp. 949–960, Jun. 2013.
[16] C. L. Salazar and T. D. Tran, “On resizing images in the DCT domain,” in International Conference on Image Processing, 2004. ICIP ’04, Singapore, 2004, pp. 2797–2800 Vol. 4.
[17] K. Sayood. Introduction to Data Compression, 3 rd ed., San Francisco, CA, USA: pp. 391–422, 2006. Morgan Kaufmann.
[18] G. A. F. Seber, A Matrix Handbook for Statisticians, Hoboken, NJ, USA, 2008. Wiley.
[19] G. J. Sullivan, J. Ohm, W. Han and T. Wiegand, “Overview of the High Efficiency Video Coding (HEVC) Standard,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 22, no. 12, pp. 1649–1668, Dec. 2012.
[20] H. Thoma, M. de-Frutos-Lpez, and J. Auer, “Chroma subsampling for HDR video with improved subjective quality,” Picture Coding Symposium, pp. 345–348, Dec. 2013.
[21] G. K. Wallace, “The JPEG still picture compression standard,” IEEE Transactions on Consumer Electronics, vol. 38, no. 1, pp. xviii–xxxiv, Feb. 1992.
[22] S. Wang, K. Gu, R. S. Ma, and W. Gao, “Joint chroma downsampling and upsampling for screen content image,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 26, no. 9, pp. 1595–1609, Sep. 2016.
[23] T. Wiegand, G. J. Sullivan, G. Bjφntegaard and A. Luthra, “Overview of the H.264/AVC video coding standard,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 13, no. 7, pp. 560–576, July 2003.
[24] X. Wu, X. Zhang, and X. Wang, “Low bit-rate image compression via adaptive down-sampling and constrained least squares upconversion,” IEEE Transactions on Image Processing, vol. 18, no. 3, pp. 552–561, Mar. 2009.
[25] Y. Zhang, D. Zhao, J. Zhang, R. Xiong, and W. Gao, “Interpolation-dependent image downsampling,” IEEE Transactions on Image Processing, vol. 20, no. 11, pp. 3291–3296, Nov. 2011.
[26] S. Zhu, C. Cui, R. Xiong, Y. Guo, and B. Zeng, “Efficient Chroma Sub-Sampling and Luma Modification for Color Image Compression,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 29, no. 5, pp. 1559–1563, May. 2019.
[27] S. Y. Zhu, Z. Y. He, C. Chen, S. C. Lin, J. Zhou, Y. Guo, and B. Zeng, “High-Quality Color Image Compression by Quantization Crossing Color Spaces,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 29, no. 5, pp. 1474–1487, May. 2019.