Pull-through transforms
A code card for Pokémon TCG Live
。关于这个话题，WPS官方版本下载提供了深入分析
You look at a region of the image. If all the pixels are roughly the same color (below some threshold), you store the average color for the whole region as a single value. If the pixels vary too much, you split the region into four quadrants and try again.
（作者单位：中国社会科学院考古研究所）