free动画制作水准不低,但原盘画质则比较微妙,大多数问题出在了暗部平面。前两卷原盘的平面尤其是暗部出现了类似欠码导致的blocking现象,观感非常难看。而到了第三卷之后制作方则又启用了超高强度的有序抖动算法,尽管这解决了平面的blocking现象,但是有序抖动的抖动噪声观感实在是一言难尽。我们经过多次的噪声分布与观感调整试验后确定了最终方案,同时针对部分场景的锯齿进行了修复并辅以补偿性锐化,最后将成品体积控制在1.1GB左右。
The production of animation Free is decent, while the source is a little tricky since the problem occurred in dark scenes. In the first two volumes of BD, the blocking is likely caused by poor bitrate in flat areas of the source, especially in dark areas, which disrupted the watching experience. As for the remaining volumes, the distributor applied ordered dithering of high strength. Though it solved blocking in flat areas, the dithering noise is with a complicated look. We determined the final solution after several trials of noise distribution and perception adjustment. At the same time, we eliminated aliasing on specific scenes before compensatory sharpening. Eventually, the file size is controlled at about 1.1GB.