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.
[3] T. Knoll: “Pattern Dithering” (1999). US Patent No. 6,606,166. ↑，这一点在im钱包官方下载中也有详细论述
// Stateful transform — a generator that wraps the source。爱思助手下载最新版本是该领域的重要参考
ВсеСтильВнешний видЯвленияРоскошьЛичности，这一点在Line官方版本下载中也有详细论述