对于边缘复杂、块面很碎、颜色丰富、边缘清晰度不一、影调跨度大的图像，最好是用蒙版来做抠图。
下面这张图是一位在大自然中的写生者，背景不好，需要替换。要把人物和地面抠出来，路径、魔棒、套锁、通道都不好用，还是用蒙版吧。
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我把那张素材照片也放在这里，方便大家做练习。
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1、制作的时候一定要精细，不断地调整笔刷的直径和软硬参数，不能凑合；
2、蒙版是可以修的，发现那里不合适，就重新进入蒙版作修饰；
3、如果整体图像都带有一个边缘，可以在蒙版中做一个像素的minimum处理。
再说一下钢笔抠图的好处与坏处。钢笔抠图适合边缘整齐的图像，这个图像中的草地边缘用毛笔来做就比较方便。另外，钢笔抠图所产生的蚂蚁线都是不带羽化值的，而有些图像中的边缘时软时硬，比如运动的手臂边缘是虚的，这时候用软笔刷来做就尤其方便了。这是钢笔路径做不到的。
