The Bayer color filter array (CFA) pattern has been widely used in modern digital color cameras, and the captured image is called the Bayer CFA image $I^{Bayer}$ . Chroma downsampling is a necessary and important step in the coding system. In this paper, a novel and optimal luma modification-based chroma downsampling (LMCD) method is proposed for $I^{Bayer}$ . For each converted $2\times 2$ YUV block, the downsampled $(U, V)$ -pair and the modified luma values by the proposed LMCD method can be optimally determined, and the optimal variant of our LMCD method associated with the two modified luma values has the best quality among all sixteen variants of LMCD. Based on the Kodak and IMAX datasets, on the High Efficiency Video Coding (HEVC) platform HM-16.18, the Versatile Video Coding (VVC) platform VTM-8.0, and the Joint Photographic Experts Group (JPEG) platform, the comprehensive experimental data showed the substantial quality and quality-bitrate tradeoff merits of the reconstructed images by our optimal LMCD method relative to the traditional and state-of-the-art chroma downsampling methods.

中文翻译：

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基于新型和最佳亮度修正的色度降采样的拜耳彩色滤光片阵列图像

拜耳彩色滤光片阵列（CFA）模式已广泛用于现代数码彩色相机中，并且捕获的图像称为拜耳CFA图像 $ I ^ {Bayer} $ 。色度下采样是编码系统中必不可少的重要步骤。本文提出了一种基于亮度修正的新型最优色度下采样（LMCD）方法。 $ I ^ {Bayer} $ 。对于每个转换 2美元/次2美元 YUV块，下采样 $（U，V）$ 对和通过提议的LMCD方法修改后的亮度值可以得到最佳确定，并且与这两种修改后的亮度值相关联的LMCD方法的最优变体在LMCD的所有十六种变体中质量最高。基于柯达和IMAX数据集，在高效视频编码（HEVC）平台HM-16.18，多功能视频编码（VVC）平台VTM-8.0和联合图像专家组（JPEG）平台上，综合实验数据显示与传统的和最新的色度降采样方法相比，通过我们的最佳LMCD方法，重构图像具有实质性的质量和质量比特率的优缺点。