Python PIL : Make pixels outside a polygon transparent

Question

目前，为了使多边形透明，我正在做，

img = Image.open("")
back = Image.new('RGBA', img.size)
back.paste(img)
poly = Image.new('RGBA', (512,512))
pdraw = ImageDraw.Draw(poly)
pdraw.rectangle([(10,10),(100,100)],
          fill=(255,255,255,200))

back.paste(poly, (0,0), mask=poly)
back.show()

但是我想要的是多边形外部的所有区域都是透明的，并且多边形内部的区域相同。基本上，与我现在正在做的相反。

Answer 1

您可以使用ImageOps反转蒙版。

from PIL import ImageOps   

img = Image.open("")
back = Image.new('RGBA', img.size)
back.paste(img)
poly = Image.new('RGBA', (512,512))
pdraw = ImageDraw.Draw(poly)
pdraw.rectangle([(10,10),(100,100)],
          fill=(255,255,255,200))
inverted_poly = ImageOps.invert(poly)
back.paste(poly, (0,0), mask=inverted_poly)
back.show()