n.柱状图
Levels should only be adjusted to the start points of the histogram graph on both shadows and highlights. 色阶工具只能通过移动色阶柱状图的起止点来调整暗调和高光。
Also, the software will analyze the image histogram to determine the brightness and contrast settings for the image display. 同时，软件也会分析图片的柱状图，用以确定如何显示加载图片的亮度和对比度。
