layer.grayscale < number>

Grayscale converts all colors to gray. Grayscale is defined with a number between 0 and 100 where 100 turns all colors to a shade of gray. The default value is 0.
译：灰度所有颜色转换为灰度。 灰度是定义一个介于0和100，其中100所有颜色变成了灰色的阴影。默认值为0。

layerA = new Layer
layerA.grayscale = 100