Chroma subsampling is a significant step which reduces color information before encoding the RGB full-color image in JPEG compression. In this paper, we integrate different chroma subsampling and upsampling methods into Baseline JPEG codec to find the best combination for quality improvement. Prior to JPEG encoding, we implement traditional 4:2:0 chroma subsampling methods, including 4:2:0(A), 4:2:0(L), 4:2:0(R), 4:2:0(DIRECT), 4:2:0(MPEG_B), 4:2:0(BRIGHT) and 4:2:0(BRIGHT_MEAN) as well as adaptive chroma subsampling methods, such as Quality Preserving Luma Adaptation-based Chroma Subsampling (QPLACS), Interpolation-Dependent Image Downsampling (IDID) and Joint Chroma Downsampling and Upsampling (JCDU). At the client side, the considered upsampling methods are COPY, BILINEAR, BICUBIC and Augmented Bilinear Interpolation based upsampling (ABIL) methods. The overall experimental results on Kodak and IMAX datasets demonstrate that the best combination of chroma subsampling-upsampling scheme is QPLACS-BILINEAR, which can achieve high quality-preserving effects, such as Color-Peak-Signal-Noise-Ratio (CPSNR), Structural Similarity Index (SSIM) and Feature Similarity Index (FSIM). Furthermore, it can also gain substantial improvement in the quality-bitrate tradeoff of reconstructed RGB full-color images.

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