论文标题
改进了VVC中颜色图像的基于梯度下降的色度亚采样方法
Improved gradient descent-based chroma subsampling method for color images in VVC
论文作者
论文摘要
在编码RGB全彩色的颜色图像之前，拜耳颜色滤清器阵列（CFA）和数字时间延迟集成（DTDI）CFA图像，对其转换的色度图像进行色度亚采样是必要且重要的。 在本文中，我们提出了一种有效的基于梯度下降的色度亚采样方法，用于上述三种颜色图像，与相关方法相比，在重建的颜色图像方面实现了重建的颜色图像的实质性质量和质量 - 双位折衷。首先，基于双线性插值2 $ \ times $ 2 $ t $（$ \ in \ {rgb，bayer，bayer，dtdi \} $）颜色块 - 延伸功能在服务器端提出，然后在实际域中，然后在实际域中，我们证明我们的一般2 $ \ times 2 $ \ times $ 2 $ 2 $ 2 $ t $ block-block-block-block-distertall block-distorth-distortial函数是convex功能。此外，得出了一般的封闭式，以确定每2 $ \ times $ 2色度块的最初采样色度对。最后，开发了一种有效的迭代方法来改善最初的$（u，v）$ - 对。基于柯达和IMAX数据集，全面的实验结果表明，在新发布的多功能视频编码（VVC）平台VTM-8.0上，对于上述三种颜色图像，我们的Chroma子采样方法显然超过了现有的Chroma子采样方法。
Prior to encoding color images for RGB full-color, Bayer color filter array (CFA), and digital time delay integration (DTDI) CFA images, performing chroma subsampling on their converted chroma images is necessary and important. In this paper, we propose an effective general gradient descent-based chroma subsampling method for the above three kinds of color images, achieving substantial quality and quality-bitrate tradeoff improvement of the reconstructed color images when compared with the related methods. First, a bilinear interpolation based 2$\times$2 $t$ ($\in \{RGB, Bayer, DTDI\}$) color block-distortion function is proposed at the server side, and then in real domain, we prove that our general 2$\times$2 $t$ color block-distortion function is a convex function. Furthermore, a general closed form is derived to determine the initially subsampled chroma pair for each 2$\times$2 chroma block. Finally, an effective iterative method is developed to improve the initially subsampled $(U, V)$-pair. Based on the Kodak and IMAX datasets, the comprehensive experimental results demonstrated that on the newly released versatile video coding (VVC) platform VTM-8.0, for the above three kinds of color images, our chroma subsampling method clearly outperforms the existing chroma subsampling methods.
