Python Wand 将 PDF 转换为 PNG 禁用透明(alpha_channel)

Question

我正在尝试将 PDF 转换为 PNG - 这一切正常，但是，即使我相信我已禁用它，输出图像仍然是透明的:

with Image(filename='sample.pdf', resolution=300) as img:
    img.background_color = Color("white")
    img.alpha_channel = False
    img.save(filename='image.png')

上面生成的图像是透明的，我也尝试了下面的:

with Image(filename='sample.pdf', resolution=300, background=Color('white')) as img:
    img.alpha_channel = False
    img.save(filename='image.png')

产生此错误:

Traceback (most recent call last):
  File "file_convert.py", line 20, in <module>
    with Image(filename='sample.pdf', resolution=300, background=Color('white')) as img:
  File "/Users/Frank/.virtualenvs/wand/lib/python2.7/site-packages/wand/image.py", line 1943, in __init__
    raise TypeError("blank image parameters can't be used with image "
TypeError: blank image parameters can't be used with image opening parameters

Answer 1

我还有一些 PDF 可以转换为 PNG。这对我有用，而且看起来比合成图像更简单，如上所示。:

from wand.image import Image
from wand.color import Color

all_pages = Image(blob=self.pdf)        # PDF will have several pages.
single_image = all_pages.sequence[0]    # Just work on first page
with Image(single_image) as i:
    i.format = 'png'
    i.background_color = Color('white') # Set white background.
    i.alpha_channel = 'remove'          # Remove transparency and replace with bg.

引用:wand.image