Weighted Edge Sharpening Filtering for Upscaled Content in Adaptive Resolution Coding.

Reference Picture Resampling (RPR) is an essential tool for quickly adapting to varying network conditions. It enables a resolution change without the introduction of an intra random access point (IRAP). This feature is particularly crucial in real-time transmission scenarios and has proven effective for compressing high-resolution pictures. However, a significant challenge of Reference Picture Resampling is the loss of high-frequency information in the downscaling operation. This results in blurred pictures after upscaling, which significantly affects the viewer experience. To address this issue, we propose an additional enhancement step after upscaling. The proposed enhancement method involves a locally weighted adaptive filter specifically designed for edge sharpening. Through the application of local weighting, we can avoid the common problems associated with linear high-pass filters. Picture-wise content adaptivity helps in handling different scene characteristics. The proposed method is implemented into the enhanced compression model 8.0 (ECM) and achieves performance gains for the joint video experts team (JVET) common testing conditions for reference picture resampling (RPR), with a Bjøntegaard delta-rate (BD-rate) reduction of -7.27%, -0.57%, and -0.32% for the Y, Cb, and Cr channels, respectively.