Existing mezzanine image codecs lack specialized screen content coding tools and therefore struggle to maintain high image quality under bandwidth constraints, especially in areas with dense text. Although distribution codecs offer advanced screen content compression techniques, their high computational complexity makes them impractical for mezzanine coding. To address this shortfall, we introduce the High-quality Lightweight Codec (HLC), a solution centered on enabling practical, high-throughput palette for mezzanine coding. The core innovation is a novel data-dependency-free palette that eliminates the throughput bottlenecks. To ensure its effectiveness across all content, a co-designed rate-distortion optimization module arbitrates between the palette and traditional prediction modes, while a data reuse strategy between rate estimation and entropy coding minimizes the overall hardware resources required for the system. Experimental results show that, compared with a 4K@120fps JPEG-XS encoder, HLC achieves the same throughput while using only half the LUT resources and delivers BD-PSNR improvements of 3.461dB, 3.299dB, and 5.312dB on gaming, natural, and text content datasets, respectively.

翻译：现有中间图像编解码器缺乏专用屏幕内容编码工具，因此在带宽受限条件下难以维持高图像质量，尤其是在密集文本区域。尽管分发编解码器具备先进的屏幕内容压缩技术，但其高计算复杂度使其难以应用于中间编码。为弥补这一不足，我们提出高质量轻量级编解码器（HLC），该方案以实现实用化、高吞吐调色板技术为核心，适用于中间编码场景。核心创新在于一种无数据依赖性的调色板设计，消除了吞吐瓶颈。为确保该技术对所有内容的有效性，协同设计的率失真优化模块在调色板与传统预测模式间进行仲裁，同时率估计与熵编码间的数据重用策略最大程度降低了系统所需的整体硬件资源。实验结果表明：与4K@120fps JPEG-XS编码器相比，HLC在实现同等吞吐量的同时仅消耗其一半的LUT资源，并在游戏、自然及文本内容数据集上分别实现了3.461dB、3.299dB和5.312dB的BD-PSNR提升。